WO2006097649A1 - Method and device for generating a thermal flux loaded with particles - Google Patents
Method and device for generating a thermal flux loaded with particles Download PDFInfo
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- WO2006097649A1 WO2006097649A1 PCT/FR2006/050193 FR2006050193W WO2006097649A1 WO 2006097649 A1 WO2006097649 A1 WO 2006097649A1 FR 2006050193 W FR2006050193 W FR 2006050193W WO 2006097649 A1 WO2006097649 A1 WO 2006097649A1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/0006—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature
- H05H1/0012—Investigating plasma, e.g. measuring the degree of ionisation or the electron temperature using electromagnetic or particle radiation, e.g. interferometry
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/26—Plasma torches
- H05H1/32—Plasma torches using an arc
- H05H1/42—Plasma torches using an arc with provisions for introducing materials into the plasma, e.g. powder or liquid
Definitions
- the present invention relates to a method and a device for generating a particle-laden heat flux for characterizing materials subjected to severe thermal environments.
- spacecraft such as probes are subjected to various assaults (micrometeorites, ultraviolet radiation and ionizing agents, etc.).
- assaults micrometeorites, ultraviolet radiation and ionizing agents, etc.
- a particularly severe source of aggression for the structure of such a probe appears during atmospheric re-entry. Indeed, the probe is then subjected to abrasive thermal aggressions related to the presence of solid or liquid particles in the atmosphere of the star and the
- Powder propellants which have a relatively large proportion of alumina particles in their jet.
- These gases are typically generated either by glow discharge type sources or by inductively coupled plasma sources. The higher the energies of these sources, the more they can provide a very hot gas in large quantities, controlled and constant for carrying out tests on representative samples, i.e. of large sizes.
- US Pat. No. 3,893,335 Discloses a device for simulating the conditions of re-entry into a particle-laden atmosphere.
- This device supplies a hot air flow generated by an arc plasma to a nozzle, the flow at the outlet of this nozzle being directed towards the sample to be analyzed.
- particles with high velocities of up to 6000 m / s are injected into the hot air stream downstream of this nozzle.
- these particles are accelerated independently of the hot air flow at a speed determined by the operator.
- This simulation method therefore requires particularly complex and bulky means to accelerate the particles solid at such speeds but also poses problems mixing two very hypersonic gas streams.
- the present invention proposes a method and a device for generating a heat flux loaded with simple particles in their design and in their operating mode to simulate in a controlled manner the heat flows loaded with particles representative of powder propellants or planetary reentries in order to characterization of standard size samples for the space and / or aeronautical field.
- the subject of the invention is a method for generating a heat flux charged with particles, these particles being at least partially directed on an object, into which a carrier gas and particles are injected from at least one injector. of particles having at least one exit port, in a plasma jet directed from the end of a plasma source outwardly along a major axis, the plasma jet having a core.
- the axial and radial positions of this particle injector are adjusted with respect to the main axis and the inclination of this injector with respect to an axis perpendicular to the main axis, and the momentum is controlled particles at the nozzle outlet to drive the particles evenly into the core of the plasma jet so that said particles acquire at a variable distance D from the end of the plasma source a maximum average speed, and
- this distance D is determined from the end of the plasma source and the object is positioned at approximately this distance D.
- the particle velocities in propellant jets of solid propellant rockets can reach from 1000 m / s to 3000 m / s.
- the object to be characterized is positioned in the jet of plasma charged particles, in the vicinity of where the average particle velocity is maximum, this speed being adjustable. This ensures that the sample is placed at a place where the particles have acquired a medium speed sufficient for characterization.
- the object of the invention is therefore achieved on the one hand by adjusting the amount of movement of the particles at the outlet of at least one injector and by controlling the position of said outlet orifice to make the plasma jet charged of particles as homogeneous as possible, and secondly by determining the position D, variable along the main axis, where the particles acquire a maximum average speed so as to position the object to be characterized around this place .
- the present invention also relates to the following features which should be considered in isolation or in all their technically possible combinations:
- the maximum average velocity of the particles is measured and the speed of the plasma jet is adjusted to a determined speed value
- the average trajectory of the particles of the outlet orifice of the injector and in the plasma jet is determined by using a first optical detector so as to adjust the position and inclination of this injector and to adjust the momentum particle average at the exit of the particle injector,
- the average speed of each particle is measured by illuminating this particle at at least three different times by using a light source generating pulses of light, and detecting in a single image the corresponding reflected light using a second optical detector, the second optical detector and the light source being synchronized.
- the invention also relates to a device for generating a charged thermal flux of particles comprising:
- a plasma source comprising a plasma source end having a main axis along which a plasma jet is directed outwards
- At least one particle injector having at least one outlet orifice, said particle injector being intended for injecting a carrier gas and particles into the piasma jet.
- this device comprises:
- a support that can be divided in two directions in order to position said injector axially and radially with respect to said main axis and inclination means for controlling the angular position of said injector with respect to an axis perpendicular to said main axis,
- a first optical detector and display means for detecting the mean trajectory of the particles from the exit of the injector and in the plasma jet, and means for determining the average speed of said particles.
- the present invention also relates to the following characteristics which should be considered in isolation or in all their technically possible combinations: the particles are chosen from the group comprising Al 2 O 3; , SiO 2 ,
- the injector comprises a flow regulator for controlling the flow of the carrier gas used to inject the particles so as to control the average amount of movement of these particles at the outlet of the injector,
- the particle size is between about 20 and 40 micrometers
- the concentration of particles is between about 0.001 and 40 percent by mass of the plasma jet, the concentration of particles is between about 20 and 40 percent by weight of the plasma jet.
- FIG. 2 is a schematic representation of the device for generating a charged particle flux according to another embodiment of the invention
- FIG. 3 schematically shows the average trajectories followed by the particles as a function of the arc current associated with a volume flow rate of air for a particular mode of implementation of the invention
- FIG. 4 schematically shows the distribution of the mean particle velocities (m / s) along the principal axis as a function of the applied arc current (A), the distance on the x-axis being measured from the end of the plasma source (in mm).
- FIG. 1 shows a device for generating a particle-laden heat flux according to one embodiment of the invention.
- This device comprises a plasma source 1 comprising a source end having a main axis 2.
- the plasma source 1 is advantageously a plasma torch.
- the plasma torch is an AQTIL plasma torch marketed by EADS ST.
- This high-power torch comprises two coaxial copper tubular electrodes between which the plasma gas is injected with a large tangential velocity. The electrodes are cooled with water. This torch can advantageously operate stably in a wide range of current intensity and air flow rates.
- the source of piasma 1 produces a plasma jet 3 directed outwards along this main axis 2.
- a sample 4 placed along this main axis 2 receives the plasma jet 3.
- the device comprises at least one particle injector 5 having at least one exit orifice 6.
- This particle injector 5 is intended to inject a carrier gas and particles into the plasma jet at the outlet of the plasma source 1
- the carrier gas of the particles is used to
- the flow rate of the carrier gas is set according to the nature of the particles, its particle size distribution and also the power dissipated in the plasma jet 3. However, this flow rate remains constant. very low compared to the flow rate of the plasma jet 3 so that the perturbation generated by penetration of the particles is negligible. As an illustration, for a volume flow of air between 1500 and 8000 l / min, the volume flow rate of the carrier gas is less than 20 l / min.
- the device comprises several injectors 5 distributed homogeneously around the plasma jet 3. The number of injectors 5 is advantageously between 2 and 8.
- the injector 5 may comprise a flow regulator for controlling the flow of the carrier gas used to inject the particles so as to control the average amount of movement of these particles at the outlet of the injector 5.
- a support 8 movable in two directions allows axially and radially position the injector 5 with respect to the main axis 2 of the end of the plasma source 1 and tilting means to control its angular position with respect to an axis perpendicular to the axis 7 main 2 ( Figure 2).
- the support 8 is, for example, an arm mounted on a displacement table in a plane xy parallel to the main axis 2, It also makes it possible to adjust the position of the outlet orifice 6 of this injector 5 along the axis perpendicular 7 to Main Tax 2. The movement of this arm can be motorized or not.
- the tilting means of the injector make it possible to incline it by an angle between 0 ° and 90 ° towards the end of the plasma source 1.
- the size of the particles is between about 20 and 40 microns and their concentration is between about 0.001 and 40 percent by weight of the plasma jet.
- the particle concentration will rather be between about 20 and 40 percent by mass of the plasma jet.
- the particles are advantageously chosen from the group comprising Al 2 O 3 , SiO 2 , FeOH, Fe 3 O 4 and combinations thereof.
- Particles AI 2 O 3 and SiO 2 are preferred in simulations of a powder propellant, whereas particles of FeOH, Fe 3 O 4 are preferred for simulations of atmospheric re-entry and, in particular, of returned to the Martian atmosphere.
- Other particles could be implemented to simulate other environments.
- the device comprises a first optical detector 9, for example an infrared video camera and display means such as a screen for detecting and visualizing the average trajectory of the particles from the outlet orifice 6 of the injector 5 and in the jet of plasma 3.
- a first optical detector 9 for example an infrared video camera
- display means such as a screen for detecting and visualizing the average trajectory of the particles from the outlet orifice 6 of the injector 5 and in the jet of plasma 3.
- the device comprises means for determining the average speed of said particles.
- These means advantageously comprise a light source 10 generating pulses of light and a second optical detector 11.
- the second optical detector 11 and the light source 10 are synchronized.
- the light source 10 is a semiconductor laser source and the second optical detector 11 is a fast camera for recording images at high speeds.
- This camera 11 is capable of detecting low light intensities. Since this camera 11 is for example a CCD camera having a line-column matrix of pixels, each measurement is assigned at least one coordinate x representing the distance of the particle along the main axis 2 with respect to the end of the plasma source 1 at a time t.
- the speed of each particle is measured by illuminating the particles at at least three different times.
- the average speed of each particle is then obtained by relating the distance traveled by the particle measured between two measurement points by the time separating two successive pulses of the light source 10.
- the CCD camera remains open during the at least three exposures so as to visualize the three or more positions of the particles on one and the same image by superposition.
- the information collected by this second detector 11 is advantageously used with those of the first detector to determine the average trajectory of the particles from the outlet of the injector (s) 5 and in the plasma jet 3.
- the device may comprise a sample holder 12, which is incunable so that the surface of this sample 4 forms an angle between 0 ° and 90 ° with respect to the main axis 2 of the end of the plasma source 1.
- this sample holder 12 is suitable to receive samples 4 of standard size, that is to say of a size representative of the elements implemented as structural elements of a coating thermal of a spacecraft for example.
- the present invention thus lends itself to so-called “inclined board” tests, representative of the sides of the reentry vehicles or thrusters when the heat flow is partly tangential to the surface of the materials. In “inclined board”, a square sample with a minimum size of 300 mm by 300 mm is used as standard, and a sample with a minimum diameter of 25 mm is used as "breakpoint".
- FIG. 2 shows a device of the invention according to another embodiment. Elements with the same references as in Figure 1 represent the same objects.
- This device differs from that of FIG. 1, in that the end of the plasma source 1 is connected to a vacuum chamber 13 in which the plasma jet 3 is directed.
- This chamber 13 is pumped by a unit of pumping.
- This pumping unit comprises for example at least one high-speed primary pump.
- On the enclosure 13 is mounted at least one metering valve 14 connected to a metering device pumped for example by a primary pump, and a pressure gauge for introducing a gas into this chamber 13 by means of the metering valve 14 and of the dosing device.
- This gas is for example CO 2 .
- This device also comprises a diffuser 15 for discharging the plasma jet 3.
- the injector 5 is positioned to inject the particles from bottom to top.
- the invention also relates to a method for generating a charged heat flux of particles, the particles being at least partially directed on an object 4.
- a carrier gas and particles are injected from at least one particle injector. 5 having at least one outlet port 6 in a plasma jet 3.
- This plasma jet 3 is directed from the end of a plasma source 1 outwardly along a main axis 2.
- This jet of plasma 3 has a heart.
- this particle injector 5 The axial and radial positions of this particle injector 5 are then adjusted with respect to the main axis 2 and the inclination of this injector 5 with respect to an axis perpendicular to said main axis 2 and the average amount of movement of the particles at the outlet orifice 6 of the injector 5 for homogeneously driving the particles in the core of the plasma jet 3.
- the outlet orifice 6 of the injector 5 is positioned in the jet of plasma 3, the temperature of the jet of plasma 3 being lower than the melting temperature of the constituent material of the injector 5.
- the average trajectory of the particles of the outlet orifice 6 of the injector 5 and in the plasma jet 3 is determined by using a first optical detector 9, for example an infrared video camera.
- the particles acquire at a variable distance D from the end of the plasma source 1 a maximum average speed.
- the distance D of the end of the plasma source 1 is then determined and the object 4 to be characterized is positioned at this distance D.
- the object to be characterized can also be positioned up to a position D 'of the iong of the plasma. main axis 2, from this position D, the position D 'being such that the particles still have a speed approximately equal to at least 90% of the determined maximum average particle speed.
- this maximum average speed is measured and the speed of the piasma jet is adjusted to a determined speed value.
- This adjustment of the speed of the plasma jet 3 can be achieved by adding a nozzle to the end of the plasma source 1, or by increasing the electrical operating power of the plasma source 1, or by adapting the composition of the plasma carrier gas generating the plasma.
- a gas chosen from the group comprising H 2 , CO 2 and N 2 is used .
- Figure 3 shows an embodiment of the invention for alumina powders with a plasma torch.
- the outlet orifice 6 of the injector 5 is placed at a distance h of 14 mm from the end of the plasma torch 1 along the main axis 2 and at a height I 2 of 24 mm along an axis perpendicular to this main axis 2.
- the injector 5 is not inclined with respect to this axis perpendicular to the main axis 2.
- This figure 2 shows the average trajectories of the particles from the outlet of the injector and in the plasma jet for a carrier gas of 6 L / min, as a function of the arc current (A) used to generate the piasma torch associated with a volume flow rate of the piasma torch (l / min) .
- the first curve Ci (cross) is obtained for a torque 450 A-7700 rpm
- the second curve C 2 solid triangle
- the third curve C 3 (cercie) is obtained for a torque of 180 A-1700 l / min.
- Ci curve unlike the other two curves C 2 and C 3 for which the average trajectories cut the main axis 2 to about 100 mm from the end of the plasma source 1.
- the momentum of the jet is too large compared to that related to the radial flow at the outlet of the injector.
- Figure 4 shows in a particular implementation mode the distribution of average particle velocities along the main axis as a function of the arc current (A).
- the abscissa axis 16 which represents the position of the particles along the principal axis (mm), has as its point of origin 17 the end of the plasma source and the ordinate axis 18 represents the average speed of the particles (m / s).
- the powders used are particles of alumina and the plasma source is an AQTIL plasma torch.
- the first curve Si (diamond) is obtained for a current of 450 A arc
- the second curve S 2 rectangle
- the third curve S 3 (triangle) is obtained for 180 A arc current.
- the invention can be implemented as a device for thermal spraying of particles for the deposition of coatings, for example metal, on a surface.
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Abstract
Description
PROCEDE ET DISPOSITIF POUR GENERER UN FLUX THERMIQUE CHARGE DE PARTICULESMETHOD AND DEVICE FOR GENERATING A THERMAL FLOW CHARGED WITH PARTICLES
La présente invention concerne un procédé et un dispositif pour générer un flux thermique chargé de particules en vue de caractériser des matériaux soumis à des environnements thermiques sévères.The present invention relates to a method and a device for generating a particle-laden heat flux for characterizing materials subjected to severe thermal environments.
Il est connu que les engins spatiaux tels que les sondes sont soumis à 5 des agressions diverses (micrométéorites, rayonnement ultraviolet et ionisants,...). Une source particulièrement sévère d'agressions pour la structure d'une telle sonde apparaît lors de rentrées atmosphériques. En effet, la sonde est alors soumise à des agressions thermiques abrasives liées à la présence de particules solides ou liquides dans l'atmosphère de l'astre et à laIt is known that spacecraft such as probes are subjected to various assaults (micrometeorites, ultraviolet radiation and ionizing agents, etc.). A particularly severe source of aggression for the structure of such a probe appears during atmospheric re-entry. Indeed, the probe is then subjected to abrasive thermal aggressions related to the presence of solid or liquid particles in the atmosphere of the star and the
10 vitesse de rentrée de ces engins. Ces agressions sont notamment sensibles lors de la rentrée d'une navette spatiale dans l'atmosphère terrestre puisqu'elle dissipe son énergie cinétique lut ayant permis de rester en orbite basse par frottement avec l'air de l'atmosphère. Ces agressions thermiques abrasives surviennent également dans les systèmes de propulsion tels que10 speed of entry of these machines. These attacks are particularly sensitive when returning a space shuttle into the Earth's atmosphere since it dissipates its kinetic energy lut allowing to stay in low orbit by friction with the air of the atmosphere. These abrasive thermal aggressions also occur in propulsion systems such as
15 les propulseurs à poudre qui présentent une part relativement importante de particules d'alumine dans leur jet.Powder propellants which have a relatively large proportion of alumina particles in their jet.
Il est donc essentiel de pouvoir simuler ces environnements induits en laboratoire pour prédire par des essais et des simulations l'évolution du comportement de matériaux ou d'objets tels qu'un revêtement thermiqueIt is therefore essential to be able to simulate these laboratory-induced environments to predict through experiments and simulations the evolution of the behavior of materials or objects such as a thermal coating.
20 destiné à devenir l'élément structural d'un bouclier de rentrée d'un véhicule spatial ou encore d'un divergent de tuyère. Jusqu'à présent, pour caractériser des matériaux, des gaz très chauds pouvant atteindre ou dépasser 30000C ont été mis en œuvre sur de petits échantillons disposés de manière adéquate, par exemple en "point d'arrêt", i.e. les gaz arrivant perpendiculairement à la surface des échantillons, ou "en planche inclinée", i.e. les gaz arrivant sensiblement tangentiellement à la surface des échantillons.20 to become the structural element of a retraction shield of a spacecraft or a divergent nozzle. Until now, in order to characterize materials, very hot gases that can reach or exceed 3000 ° C. have been used on small samples that are suitably arranged, for example "breakpoint", ie the gases arriving perpendicularly. at the surface of the samples, or "inclined board", ie the gases arriving substantially tangentially to the surface of the samples.
Ces gaz sont typiquement générés soit par des sources du type à décharge luminescente, soit par des sources à plasma à couplage inductif. Plus les énergies de ces sources sont importantes, plus elles peuvent fournir un gaz très chaud en grande quantité, maîtrisé et constant pour la réalisation d'essais sur des échantillons représentatifs, i.e. de grandes tailles.These gases are typically generated either by glow discharge type sources or by inductively coupled plasma sources. The higher the energies of these sources, the more they can provide a very hot gas in large quantities, controlled and constant for carrying out tests on representative samples, i.e. of large sizes.
Ces méthodes de simulation d'environnements extrêmes se sont révélées satisfaisantes pour développer les systèmes de lanceurs spatiaux et de sondes spatiales connus jusqu'à présent. Néanmoins, la recherche permanente d'une optimisation des structures mises en œuvre dans les engins spatiaux, par exemple pour l'obtention d'éléments structuraux présentant une résistance toujours plus élevée aux contraintes mécaniques et/ou thermiques pour une masse minimale, requière un affinement de ces méthodes de simulation en vue de la caractérisation de ces structures.These extreme environment simulation methods have proved satisfactory for the development of space launcher and space probe systems known to date. Nevertheless, the permanent search for an optimization of the structures implemented in spacecraft, for example to obtain structural elements presenting an ever higher resistance to mechanical and / or thermal stresses for a minimum mass, requires a refinement of these simulation methods to characterize these structures.
En effet, les méthodes de simulation connues ne prennent pas en compte, ou de manière non appropriée, les phénomènes d'abrasion par des particules solides ou liquides rencontrées soit sur les astres ayant des atmosphères, soit dans les propulseurs à poudre mentionnés plus hauts. On connaît par le brevet US 3,893,335 (Jonhson et al.) un dispositif pour simuler les conditions de rentrée dans une atmosphère chargée en particules. Ce dispositif fournit un flux d'air chaud généré par un plasma d'arc à une tuyère, le flux en sortie de cette tuyère étant dirigé vers l'échantillon à analyser. Pour charger ce flux en particules, des particules présentant des vitesses élevées pouvant atteindre quelques 6000 m/s sont injectées dans le flux d'air chaud en aval de cette tuyère. Cependant, ces particules sont accélérées indépendamment du flux d'air chaud à une vitesse déterminée par l'opérateur. Cette méthode de simulation requière donc des moyens particulièrement complexes et encombrants pour accélérer les particules solides à de telles vitesses mais pose également des problèmes de mélange de deux flux de gaz très hypersoniques.Indeed, the known simulation methods do not take into account, or improperly, abrasion phenomena by solid or liquid particles encountered either on the stars having atmospheres, or in the aforementioned powder propellants. US Pat. No. 3,893,335 (Jonhson et al.) Discloses a device for simulating the conditions of re-entry into a particle-laden atmosphere. This device supplies a hot air flow generated by an arc plasma to a nozzle, the flow at the outlet of this nozzle being directed towards the sample to be analyzed. To charge this particle stream, particles with high velocities of up to 6000 m / s are injected into the hot air stream downstream of this nozzle. However, these particles are accelerated independently of the hot air flow at a speed determined by the operator. This simulation method therefore requires particularly complex and bulky means to accelerate the particles solid at such speeds but also poses problems mixing two very hypersonic gas streams.
On connaît également par le document "Mars entry simulation with dust using an inductively heated generator", 22πd Aerodynamic Measurement Technology and Ground Testing Conférence, 2002, AIAA 2002-3237; un dispositif de simulation utilisant une source de plasma à couplage inductif ("Inductively coupled plasma" - ICP) reliée à une enceinte sous vide évacuée par une unité de pompage. L'injection des particules solides dans le flux gazeux est réalisée avant la source de plasma ICP, dans le gaz porteur du plasma. Cette méthode s'avère donc extrêmement défavorable puisqu'elle entraîne non seulement une usure accélérée du dispositif mais elle altère également la qualité du jet gazeux chargé en particules. En effet, les produits d'abrasion résultant de l'interaction entre le plasma chargé en particules solides et les parois internes de l'enceinte polluent le jet gazeux. De plus, les particules sont injectées dans le plasma sans action particulière pour rendre ce flux gazeux chargé en particules représentatif en terme de température et de vitesse, ces dernières étant des paramètres importants pour simuler des phénomènes d'abrasion.It is also known from the document "Mars entry simulation with dust using an inductively heated generator", 22 πd Aerodynamic Measurement Technology and Ground Testing Conference, 2002, AIAA 2002-3237; a simulation device using an inductively coupled plasma (ICP) source connected to a vacuum chamber discharged by a pumping unit. Injection of the solid particles into the gas stream is performed before the ICP plasma source in the plasma carrier gas. This method is therefore extremely unfavorable since it not only causes accelerated wear of the device but also alters the quality of the gaseous jet charged with particles. In fact, the abrasion products resulting from the interaction between the plasma charged with solid particles and the internal walls of the enclosure pollute the gaseous jet. In addition, the particles are injected into the plasma without any particular action to make this gaseous stream loaded with particles representative in terms of temperature and speed, the latter being important parameters for simulating abrasion phenomena.
Aussi, la présente invention propose un procédé et un dispositif pour générer un flux thermique chargé de particules simples dans leur conception et dans leur mode opératoire pour simuler de manière maîtrisée les flux thermiques chargés de particules représentatifs des propulseurs à poudre ou des rentrées planétaires en vue de la caractérisation d'échantillons de taille standard destinés au domaine spatial et/ou aéronautique. A cet effet, l'invention a pour objet un procédé pour générer un flux thermique chargé de particules, ces particules étant au moins partiellement dirigées sur un objet, dans lequel on injecte un gaz porteur et des particules à partir d'au moins un injecteur de particules ayant au moins un orifice de sortie, dans un jet de plasma dirigé depuis l'extrémité d'une source de plasma vers l'extérieur le long d'un axe principal, ce jet de plasma ayant un cœur.Also, the present invention proposes a method and a device for generating a heat flux loaded with simple particles in their design and in their operating mode to simulate in a controlled manner the heat flows loaded with particles representative of powder propellants or planetary reentries in order to characterization of standard size samples for the space and / or aeronautical field. For this purpose, the subject of the invention is a method for generating a heat flux charged with particles, these particles being at least partially directed on an object, into which a carrier gas and particles are injected from at least one injector. of particles having at least one exit port, in a plasma jet directed from the end of a plasma source outwardly along a major axis, the plasma jet having a core.
Selon l'invention, on ajuste les positions axiale et radiale de cet injecteur de particules par rapport à l'axe principal et l'inclinaison de cet injecteur par rapport à un axe perpendiculaire à l'axe principal, et on contrôle la quantité de mouvement moyenne des particules à l'orifice de sortie de ['injecteur pour entraîner de manière homogène les particules dans le cœur du jet de plasma de sorte que lesdites particules acquièrent à une distance variable D de l'extrémité de la source de plasma une vitesse moyenne maximale, etAccording to the invention, the axial and radial positions of this particle injector are adjusted with respect to the main axis and the inclination of this injector with respect to an axis perpendicular to the main axis, and the momentum is controlled particles at the nozzle outlet to drive the particles evenly into the core of the plasma jet so that said particles acquire at a variable distance D from the end of the plasma source a maximum average speed, and
- on détermine cette distance D de l'extrémité de la source de plasma et on positionne l'objet à environ cette distance D.this distance D is determined from the end of the plasma source and the object is positioned at approximately this distance D.
Il est nécessaire de s'assurer de la caractérisation des objets dans les conditions les plus proches possibles des environnements réels auxquels seront soumis ces objets. A titre d'exemple, les vitesses des particules dans les jets propulsifs de fusées à ergols solides peuvent atteindre de 1000 m/s à 3000 m/s. Dans cet objectif, l'objet à caractériser est positionné dans le jet de plasma chargé en particules, dans les environs de l'endroit où la vitesse moyenne des particules est maximale, cette vitesse étant ajustable. On s'assure ainsi que l'échantillon est placé à un endroit où les particules ont acquis une vitesse moyenne suffisante pour la caractérisation. Le but de l'invention est donc atteint d'une part, en réglant la quantité de mouvement des particules à l'orifice de sortie d'au moins un injecteur et en contrôlant la position dudit orifice de sortie pour rendre le jet de plasma chargé de particules le plus homogène possible, et d'autre part, en déterminant la position D, variable le long de l'axe principal, où les particules acquièrent une vitesse moyenne maximale de manière à positionner l'objet à caractériser aux environs de cet endroit.It is necessary to ensure the characterization of objects in the closest conditions possible to the real environments to which these objects will be subjected. By way of example, the particle velocities in propellant jets of solid propellant rockets can reach from 1000 m / s to 3000 m / s. For this purpose, the object to be characterized is positioned in the jet of plasma charged particles, in the vicinity of where the average particle velocity is maximum, this speed being adjustable. This ensures that the sample is placed at a place where the particles have acquired a medium speed sufficient for characterization. The object of the invention is therefore achieved on the one hand by adjusting the amount of movement of the particles at the outlet of at least one injector and by controlling the position of said outlet orifice to make the plasma jet charged of particles as homogeneous as possible, and secondly by determining the position D, variable along the main axis, where the particles acquire a maximum average speed so as to position the object to be characterized around this place .
Dans différents modes de réalisation du procédé pour générer un flux thermique chargé de particules, la présente invention concerne également les caractéristiques suivantes qui devront être considérées isolément ou seion toutes leurs combinaisons techniquement possibles :In various embodiments of the method for generating a particle-laden heat flux, the present invention also relates to the following features which should be considered in isolation or in all their technically possible combinations:
- on mesure la vitesse moyenne maximaie des particules et on ajuste la vitesse du jet de plasma à une valeur de vitesse déterminée,the maximum average velocity of the particles is measured and the speed of the plasma jet is adjusted to a determined speed value,
- on détermine la trajectoire moyenne des particules de l'orifice de sortie de l'injecteur et dans le jet de plasma en utilisant un premier détecteur optique de manière à ajuster la position et l'inclinaison de cet injecteur et pour ajuster la quantité de mouvement moyenne des particules à la sortie de l'injecteur de particules,the average trajectory of the particles of the outlet orifice of the injector and in the plasma jet is determined by using a first optical detector so as to adjust the position and inclination of this injector and to adjust the momentum particle average at the exit of the particle injector,
- on mesure la vitesse moyenne de chaque particule en illuminant cette particule à au moins trois instants différents en utilisant une source de lumière générant des puises de lumière, et en détectant sur une seule image la lumière réfléchie correspondante en utilisant un deuxième détecteur optique, le deuxième détecteur optique et la source de lumière étant synchronisés.the average speed of each particle is measured by illuminating this particle at at least three different times by using a light source generating pulses of light, and detecting in a single image the corresponding reflected light using a second optical detector, the second optical detector and the light source being synchronized.
L'invention concerne également un dispositif pour générer un flux thermique chargé de particules comprenant:The invention also relates to a device for generating a charged thermal flux of particles comprising:
- une source de plasma comprenant une extrémité de source de plasma ayant un axe principal le long duquel est dirigé un jet de plasma vers l'extérieur,a plasma source comprising a plasma source end having a main axis along which a plasma jet is directed outwards,
- au moins un injecteur de particules ayant au moins un orifice de sortie, ledit injecteur de particules étant destiné à injecter un gaz porteur et des particules dans le jet de piasma.at least one particle injector having at least one outlet orifice, said particle injector being intended for injecting a carrier gas and particles into the piasma jet.
Selon l'invention, ce dispositif comprend:According to the invention, this device comprises:
- un support dépiaçable dans deux directions pour positionner axialement et radialement ledit injecteur par rapport audit axe principal et des moyens d'inclinaison pour contrôler la position angulaire dudit injecteur par rapport à un axe perpendiculaire audit axe principal,a support that can be divided in two directions in order to position said injector axially and radially with respect to said main axis and inclination means for controlling the angular position of said injector with respect to an axis perpendicular to said main axis,
- un premier détecteur optique et des moyens de visualisation pour détecter la trajectoire moyenne des particules depuis la sortie de î'injecteur et dans le jet de plasma, et - des moyens pour déterminer la vitesse moyenne desdites particules.a first optical detector and display means for detecting the mean trajectory of the particles from the exit of the injector and in the plasma jet, and means for determining the average speed of said particles.
Dans différents modes de réalisation du dispositif pour générer un flux thermique chargé de particules, la présente invention concerne également les caractéristiques suivantes qui devront être considérées isolément ou selon toutes leurs combinaisons techniquement possibles : - les particules sont choisies dans le groupe comprenant Ai2O3, SiO2,In various embodiments of the device for generating a heat flux loaded with particles, the present invention also relates to the following characteristics which should be considered in isolation or in all their technically possible combinations: the particles are chosen from the group comprising Al 2 O 3; , SiO 2 ,
FeOH, Fe3O4 et des combinaisons de celles-ci,FeOH, Fe 3 O 4 and combinations thereof,
- I'injecteur comprend un régulateur de débit pour contrôler le flux du gaz porteur utilisé pour injecter les particules de manière à contrôler la quantité de mouvement moyenne de ces particules à la sortie de I'injecteur,The injector comprises a flow regulator for controlling the flow of the carrier gas used to inject the particles so as to control the average amount of movement of these particles at the outlet of the injector,
- la taille des particules est comprise entre environ 20 et 40 micromètres,the particle size is between about 20 and 40 micrometers,
- la concentration de particules est comprise entre environ 0,001 et 40 pourcent en masse du jet de plasma, - la concentration de particules est comprise entre environ 20 et 40 pourcent en masse du jet de plasma.the concentration of particles is between about 0.001 and 40 percent by mass of the plasma jet, the concentration of particles is between about 20 and 40 percent by weight of the plasma jet.
Dans différents modes de réalisation possibles, l'invention sera décrite plus en détail en référence aux dessins annexés dans lesquels : - la figure 1 représente schématiquement le dispositif pour générer un flux chargé de particules selon un mode de réalisation de l'invention;In various possible embodiments, the invention will be described in more detail with reference to the accompanying drawings in which: - Figure 1 shows schematically the device for generating a charged particle stream according to one embodiment of the invention;
- la figure 2 est une représentation schématique du dispositif pour générer un flux chargé de particules selon un autre mode de réalisation de l'invention; - la figure 3 montre schématiquement les trajectoires moyennes suivies par les particules en fonction du courant d'arc associé à un débit volumique d'air pour un mode de mise en œuvre particulier de l'invention;FIG. 2 is a schematic representation of the device for generating a charged particle flux according to another embodiment of the invention; FIG. 3 schematically shows the average trajectories followed by the particles as a function of the arc current associated with a volume flow rate of air for a particular mode of implementation of the invention;
- la figure 4 montre schématiquement la distribution des vitesses moyennes des particules (m/s) le long de l'axe principal en fonction du courant d'Arc appliqué (A), la distance sur l'axe des x étant mesurée depuis l'extrémité de la source à plasma (en mm).FIG. 4 schematically shows the distribution of the mean particle velocities (m / s) along the principal axis as a function of the applied arc current (A), the distance on the x-axis being measured from the end of the plasma source (in mm).
La Figure 1 montre un dispositif pour générer un flux thermique chargé de particules selon un mode de réalisation de l'invention. Ce dispositif comprend une source de plasma 1 comportant une extrémité de source ayant un axe principal 2. La source de plasma 1 est avantageusement une torche plasma. Dans ce mode de réalisation particulier, ia torche à plasma est une torche à plasma AQTIL commercialisée par EADS ST. Cette torche de forte puissance comporte deux électrodes tubulaires coaxiales en cuivre entre lesquelles le gaz plasmagène est injecté avec une vitesse tangentielle importante. Les électrodes sont refroidies à l'eau. Cette torche peut fonctionner avantageusement de façon stable dans une large gamme d'intensité de courant et de débits d'air.Figure 1 shows a device for generating a particle-laden heat flux according to one embodiment of the invention. This device comprises a plasma source 1 comprising a source end having a main axis 2. The plasma source 1 is advantageously a plasma torch. In this particular embodiment, the plasma torch is an AQTIL plasma torch marketed by EADS ST. This high-power torch comprises two coaxial copper tubular electrodes between which the plasma gas is injected with a large tangential velocity. The electrodes are cooled with water. This torch can advantageously operate stably in a wide range of current intensity and air flow rates.
La source de piasma 1 produit un jet de plasma 3 dirigé vers l'extérieur le long de cet axe principal 2. Un échantillon 4 placé le long de cet axe principal 2 reçoit le jet de plasma 3.The source of piasma 1 produces a plasma jet 3 directed outwards along this main axis 2. A sample 4 placed along this main axis 2 receives the plasma jet 3.
Le dispositif comprend au moins un injecteur de particules 5 ayant au moins un orifice de sortie 6. Cet injecteur de particules 5 est destiné à injecter un gaz porteur et des particules dans le jet de plasma au niveau de la sortie de la source de plasma 1. Le gaz porteur des particules est utilisé pour entraîner et permettre la pénétration des particules dans ie jet de plasma 3. Le débit du gaz porteur est fixé en fonction de ia nature des particules, de sa distribution granulométrique mais aussi de la puissance dissipée dans le jet de plasma 3. Cependant ce débit reste très faible comparé au débit du jet de plasma 3 de sorte que !a perturbation générée par ia pénétration des particules est négligeable. A titre illustratif, pour un débit voiumique d'air compris entre 1500 et 8000 l/min, le débit volumique du gaz porteur est de moins de 20 l/min. Dans un mode de réalisation préférentiel, le dispositif comprend plusieurs injecteurs 5 distribués de manière homogène autour du jet de plasma 3. Le nombre d'injecteurs 5 est avantageusement compris entre 2 et 8.The device comprises at least one particle injector 5 having at least one exit orifice 6. This particle injector 5 is intended to inject a carrier gas and particles into the plasma jet at the outlet of the plasma source 1 The carrier gas of the particles is used to The flow rate of the carrier gas is set according to the nature of the particles, its particle size distribution and also the power dissipated in the plasma jet 3. However, this flow rate remains constant. very low compared to the flow rate of the plasma jet 3 so that the perturbation generated by penetration of the particles is negligible. As an illustration, for a volume flow of air between 1500 and 8000 l / min, the volume flow rate of the carrier gas is less than 20 l / min. In a preferred embodiment, the device comprises several injectors 5 distributed homogeneously around the plasma jet 3. The number of injectors 5 is advantageously between 2 and 8.
L'injecteur 5 peut comprendre un régulateur de débit pour contrôler le flux du gaz porteur utilisé pour injecter les particules de manière à contrôler la quantité de mouvement moyenne de ces particules en sortie de l'injecteur 5. Un support 8 déplaçable dans deux directions permet de positionner axialement et radialement l'injecteur 5 par rapport à l'axe principal 2 de l'extrémité de la source de plasma 1 et des moyens d'inclinaison permettent de contrôler sa position angulaire par rapport à un axe perpendiculaire 7 à l'axe principal 2 (Figure 2). Le support 8 est, par exemple, un bras monté sur une table de déplacement dans un plan x-y parallèle à l'axe principal 2, II permet également d'ajuster la position de l'orifice de sortie 6 de cet injecteur 5 le long de l'axe perpendiculaire 7 à Taxe principal 2. Le déplacement de ce bras peut être motorisé ou non. Les moyens d'inclinaison de ['injecteur permettent d'incliner celui-ci d'un angle compris entre 0° et 90° vers l'extrémité de la source de plasma 1.The injector 5 may comprise a flow regulator for controlling the flow of the carrier gas used to inject the particles so as to control the average amount of movement of these particles at the outlet of the injector 5. A support 8 movable in two directions allows axially and radially position the injector 5 with respect to the main axis 2 of the end of the plasma source 1 and tilting means to control its angular position with respect to an axis perpendicular to the axis 7 main 2 (Figure 2). The support 8 is, for example, an arm mounted on a displacement table in a plane xy parallel to the main axis 2, It also makes it possible to adjust the position of the outlet orifice 6 of this injector 5 along the axis perpendicular 7 to Main Tax 2. The movement of this arm can be motorized or not. The tilting means of the injector make it possible to incline it by an angle between 0 ° and 90 ° towards the end of the plasma source 1.
De préférence, la taille des particules est comprise entre environ 20 et 40 micromètres et leur concentration est comprise entre environ 0,001 et 40 pourcent en masse du jet de plasma. Pour simuler des jets propulsifs, la concentration de particules sera plutôt prise entre environ 20 et 40 pourcent en masse du jet de plasma.Preferably, the size of the particles is between about 20 and 40 microns and their concentration is between about 0.001 and 40 percent by weight of the plasma jet. To simulate propellant jets, the particle concentration will rather be between about 20 and 40 percent by mass of the plasma jet.
Les particules sont avantageusement choisies dans le groupe comprenant AI2O3, SiO2, FeOH, Fe3O4 et des combinaisons de celles-ci. Les particules AI2O3 et SiO2 sont préférées dans les simulations d'un propulseur à poudre, alors que les particules de FeOH, Fe3O4 sont préférées pour des simulations d'une rentrée atmosphérique et, en particulier, d'une rentrée dans l'atmosphère Martienne. D'autres particules pourraient être mises en œuvre pour simuler d'autres environnements.The particles are advantageously chosen from the group comprising Al 2 O 3 , SiO 2 , FeOH, Fe 3 O 4 and combinations thereof. Particles AI 2 O 3 and SiO 2 are preferred in simulations of a powder propellant, whereas particles of FeOH, Fe 3 O 4 are preferred for simulations of atmospheric re-entry and, in particular, of returned to the Martian atmosphere. Other particles could be implemented to simulate other environments.
Le dispositif comporte un premier détecteur optique 9, par exemple une caméra vidéo infrarouge et des moyens de visualisation tels qu'un écran pour détecter et visualiser la trajectoire moyenne des particules depuis l'orifice de sortie 6 de l'injecteur 5 et dans le jet de plasma 3.The device comprises a first optical detector 9, for example an infrared video camera and display means such as a screen for detecting and visualizing the average trajectory of the particles from the outlet orifice 6 of the injector 5 and in the jet of plasma 3.
De plus, le dispositif comprend des moyens pour déterminer ia vitesse moyenne desdites particules. Ces moyens comprennent avantageusement une source de lumière 10 générant des puises de lumière et un deuxième détecteur optique 11. Le deuxième détecteur optique 11 et la source de lumière 10 sont synchronisés. Préférentiellement, la source de lumière 10 est une source laser semi-conducteur et le deuxième détecteur optique 11 est une caméra rapide permettant l'enregistrement d'images à hautes vitesses. Cette caméra 11 est capable de détecter de faibles intensités lumineuses. Cette caméra 11 étant par exemple une caméra CCD ayant une matrice ligne- colonne de pixels, on affecte à chaque mesure au moins une coordonnée x représentant la distance de la particule le long de l'axe principal 2 par rapport à l'extrémité de la source de plasma 1 à un instant t.In addition, the device comprises means for determining the average speed of said particles. These means advantageously comprise a light source 10 generating pulses of light and a second optical detector 11. The second optical detector 11 and the light source 10 are synchronized. Preferably, the light source 10 is a semiconductor laser source and the second optical detector 11 is a fast camera for recording images at high speeds. This camera 11 is capable of detecting low light intensities. Since this camera 11 is for example a CCD camera having a line-column matrix of pixels, each measurement is assigned at least one coordinate x representing the distance of the particle along the main axis 2 with respect to the end of the plasma source 1 at a time t.
On mesure la vitesse de chaque particule en illuminant les particules à au moins trois instants différents. La vitesse moyenne de chaque particule est alors obtenu en faisant le rapport entre la distance parcourue par la particule mesurée entre deux points de mesure par le délai séparant deux puises successifs de la source de lumière 10. La caméra CCD reste ouverte pendant les au moins trois expositions de manière à visualiser les trois positions au moins des particules sur une seule et même image par superposition.The speed of each particle is measured by illuminating the particles at at least three different times. The average speed of each particle is then obtained by relating the distance traveled by the particle measured between two measurement points by the time separating two successive pulses of the light source 10. The CCD camera remains open during the at least three exposures so as to visualize the three or more positions of the particles on one and the same image by superposition.
Les informations recueillies par ce deuxième détecteur 11 sont avantageusement utilisées avec celles du premier détecteur pour déterminer Ia trajectoire moyenne des particules depuis la sortie du ou des injecteurs 5 et dans le jet de plasma 3. Le dispositif peut comprendre un porte-échantillon 12, lequel est incunable de sorte que la surface de cet échantillon 4 forme un angle compris entre 0° et 90° par rapport à i'axe principal 2 de l'extrémité de la source de plasma 1. De préférence, ce porte-échantillon 12 est apte à recevoir des échantillons 4 de taille standard, c'est-à-dire d'une taille représentative des éléments mis en œuvre comme éléments structuraux d'un revêtement thermique d'un engin spatial par exemple. La présente invention se prête ainsi aux essais dits en "planche inclinée", représentatifs des cotés des véhicules de rentrée ou des propulseurs quand le flux thermique est en partie tangentiel à la surface des matériaux. En "planche inclinée", on utilise de manière standard, un échantillon carré dont les dimensions minimales sont de 300 mm par 300 mm, et en "point d'arrêt", un échantillon d'un diamètre minimal de 25 mm.The information collected by this second detector 11 is advantageously used with those of the first detector to determine the average trajectory of the particles from the outlet of the injector (s) 5 and in the plasma jet 3. The device may comprise a sample holder 12, which is incunable so that the surface of this sample 4 forms an angle between 0 ° and 90 ° with respect to the main axis 2 of the end of the plasma source 1. Preferably, this sample holder 12 is suitable to receive samples 4 of standard size, that is to say of a size representative of the elements implemented as structural elements of a coating thermal of a spacecraft for example. The present invention thus lends itself to so-called "inclined board" tests, representative of the sides of the reentry vehicles or thrusters when the heat flow is partly tangential to the surface of the materials. In "inclined board", a square sample with a minimum size of 300 mm by 300 mm is used as standard, and a sample with a minimum diameter of 25 mm is used as "breakpoint".
La Figure 2 montre un dispositif de l'invention selon un autre mode de réalisation. Les éléments ayant les mêmes références qu'à la Figure 1 représentent les mêmes objets. Ce dispositif diffère de celui de la Figure 1 , par le fait que l'extrémité de la source de plasma 1 est reliée à une enceinte sous vide 13 dans laquelle est dirigé le jet de plasma 3. Cette enceinte 13 est pompée par une unité de pompage. Cette unité de pompage comporte par exemple au moins une pompe primaire à haut débit. Sur l'enceinte 13 est montée au moins une vanne de dosage 14 reliée à un dispositif de dosage pompée par exemple par une pompe primaire, et une jauge de pression pour introduire un gaz dans cette enceinte 13 au moyen de la vanne de dosage 14 et du dispositif de dosage. Ce gaz est par exemple du CO2. Ce dispositif comporte également un diffuseur 15 pour évacuer le jet de plasma 3. Enfin, l'injecteur 5 est positionné de façon à injecter les particules du bas vers le haut.Figure 2 shows a device of the invention according to another embodiment. Elements with the same references as in Figure 1 represent the same objects. This device differs from that of FIG. 1, in that the end of the plasma source 1 is connected to a vacuum chamber 13 in which the plasma jet 3 is directed. This chamber 13 is pumped by a unit of pumping. This pumping unit comprises for example at least one high-speed primary pump. On the enclosure 13 is mounted at least one metering valve 14 connected to a metering device pumped for example by a primary pump, and a pressure gauge for introducing a gas into this chamber 13 by means of the metering valve 14 and of the dosing device. This gas is for example CO 2 . This device also comprises a diffuser 15 for discharging the plasma jet 3. Finally, the injector 5 is positioned to inject the particles from bottom to top.
L'invention concerne également un procédé pour générer un flux thermique chargé de particules, les particules étant au moins partiellement dirigées sur un objet 4. Selon ce procédé, on injecte un gaz porteur et des particules à partir d'au moins un injecteur de particules 5 ayant au moins un orifice de sortie 6 dans un jet de plasma 3. Ce jet de plasma 3 est dirigé depuis l'extrémité d'une source de plasma 1 vers l'extérieur le long d'un axe principal 2. Ce jet de plasma 3 a un cœur.The invention also relates to a method for generating a charged heat flux of particles, the particles being at least partially directed on an object 4. According to this method, a carrier gas and particles are injected from at least one particle injector. 5 having at least one outlet port 6 in a plasma jet 3. This plasma jet 3 is directed from the end of a plasma source 1 outwardly along a main axis 2. This jet of plasma 3 has a heart.
On ajuste ensuite les positions axiale et radiale de cet injecteur de particules 5 par rapport à l'axe principal 2 et l'inclinaison de cet injecteur 5 par rapport à un axe perpendiculaire 7 audit axe principal 2 et on contrôle la quantité de mouvement moyenne des particules à l'orifice de sortie 6 de l'injecteur 5 pour entraîner de manière homogène les particules dans le cœur du jet de plasma 3. Dans un mode de réalisation, on positionne l'orifice de sortie 6 de Tinjecteur 5 dans le jet de plasma 3, la température du jet de plasma 3 étant inférieure à la température de fusion du matériau constitutif de l'injecteur 5. Afin d'ajuster les positions et l'inclinaison de l'injecteur et pour ajuster la quantité de mouvement moyenne desdites particules à la sortie de cet injecteur 5, on détermine la trajectoire moyenne des particules de l'orifice de sortie 6 de i'injecteur 5 et dans le jet de plasma 3 en utilisant un premier détecteur optique 9, par exemple une caméra vidéo infrarouge.The axial and radial positions of this particle injector 5 are then adjusted with respect to the main axis 2 and the inclination of this injector 5 with respect to an axis perpendicular to said main axis 2 and the average amount of movement of the particles at the outlet orifice 6 of the injector 5 for homogeneously driving the particles in the core of the plasma jet 3. In one embodiment, the outlet orifice 6 of the injector 5 is positioned in the jet of plasma 3, the temperature of the jet of plasma 3 being lower than the melting temperature of the constituent material of the injector 5. In order to adjust the positions and the inclination of the injector and to adjust the average amount of movement of said particles at the outlet of this injector 5, the average trajectory of the particles of the outlet orifice 6 of the injector 5 and in the plasma jet 3 is determined by using a first optical detector 9, for example an infrared video camera.
Les particules acquièrent à une distance variable D de l'extrémité de la source de plasma 1 une vitesse moyenne maximale. On détermine alors la distance D de l'extrémité de la source de plasma 1 et on positionne l'objet 4 à caractériser à cette distance D. L'objet à caractériser peut également être positionné jusqu'à une position D' le iong de l'axe principal 2, à partir de cette position D, la position D' étant telle que les particules présentent encore une vitesse approximativement égale à au moins 90% de la vitesse moyenne maximale des particules déterminée. Avantageusement, on mesure cette vitesse moyenne maximale et on ajuste la vitesse du jet de piasma à une valeur de vitesse déterminée. Cet ajustement de la vitesse du jet de plasma 3 peut être réalisée en ajoutant une tuyère à l'extrémité de la source de plasma 1 , ou en augmentant la puissance électrique de fonctionnement de la source de plasma 1 , ou encore en adaptant la composition du gaz porteur générant le plasma. Dans ce dernier cas, on utilise un gaz choisi dans le groupe comprenant H2, CO2 et N2.The particles acquire at a variable distance D from the end of the plasma source 1 a maximum average speed. The distance D of the end of the plasma source 1 is then determined and the object 4 to be characterized is positioned at this distance D. The object to be characterized can also be positioned up to a position D 'of the iong of the plasma. main axis 2, from this position D, the position D 'being such that the particles still have a speed approximately equal to at least 90% of the determined maximum average particle speed. Advantageously, this maximum average speed is measured and the speed of the piasma jet is adjusted to a determined speed value. This adjustment of the speed of the plasma jet 3 can be achieved by adding a nozzle to the end of the plasma source 1, or by increasing the electrical operating power of the plasma source 1, or by adapting the composition of the plasma carrier gas generating the plasma. In the latter case, a gas chosen from the group comprising H 2 , CO 2 and N 2 is used .
La Figure 3 montre un mode de mise en oeuvre de l'invention pour des poudres d'alumine avec une torche plasma. L'orifice de sortie 6 de l'injecteur 5 est placé à une distance h de 14 mm de l'extrémité de la torche plasma 1 le long de l'axe principal 2 et à une hauteur I2 de 24 mm le long d'un axe perpendiculaire 7 à cet axe principal 2. L'injecteur 5 n'est pas incliné par rapport à cet axe perpendiculaire 7 à l'axe principal 2. Cette figure 2 montre les trajectoires moyennes des particules depuis la sortie de l'injecteur et dans le jet de plasma pour un gaz porteur de 6 L/min, en fonction du courant d'arc (A) mis en œuvre pour générer la torche piasma associé à un débit volumique d'air de la torche piasma (l/min). La première courbe C-i (croix) est obtenue pour un couple 450 A-7700 i/min, ia deuxième courbe C2 (triangle plein) est obtenue pour un couple 310 A-3400 l/min et ia troisième courbe C3 (cercie) est obtenue pour un couple 180 A-1700 l/min. Il ressort de ces courbes que les particules ne pénètrent pas au cœur du jet de plasma pour la première courbe C-i, contrairement aux deux autres courbes C2 et C3 pour lesquelles les trajectoires moyennes coupent l'axe principal 2 à environ 100 mm de l'extrémité de la source de plasma 1. La quantité de mouvement du jet est trop importante comparée à celle liée à l'écoulement radial en sortie de l'injecteur.Figure 3 shows an embodiment of the invention for alumina powders with a plasma torch. The outlet orifice 6 of the injector 5 is placed at a distance h of 14 mm from the end of the plasma torch 1 along the main axis 2 and at a height I 2 of 24 mm along an axis perpendicular to this main axis 2. The injector 5 is not inclined with respect to this axis perpendicular to the main axis 2. This figure 2 shows the average trajectories of the particles from the outlet of the injector and in the plasma jet for a carrier gas of 6 L / min, as a function of the arc current (A) used to generate the piasma torch associated with a volume flow rate of the piasma torch (l / min) . The first curve Ci (cross) is obtained for a torque 450 A-7700 rpm, the second curve C 2 (solid triangle) is obtained for a torque 310 A-3400 l / min and the third curve C 3 (cercie) is obtained for a torque of 180 A-1700 l / min. These curves show that the particles do not penetrate the core of the plasma jet for the first time. Ci curve, unlike the other two curves C 2 and C 3 for which the average trajectories cut the main axis 2 to about 100 mm from the end of the plasma source 1. The momentum of the jet is too large compared to that related to the radial flow at the outlet of the injector.
On observe donc que pour entraîner de manière homogène les particules au cœur de i'écoulement plasma, c'est-à-dire s'assurer que l'ensemble des particules soient effectivement entraînées au centre de l'écoulement du jet de plasma, ii est nécessaire non seulement d'ajuster les positions axiale et radiale de l'injecteur par rapport audit axe principal et son inclinaison par rapport à un axe perpendiculaire audit axe principal mais également de contrôler la quantité de mouvement moyenne de ces particules à l'orifice de sortie de cet injecteur.It is therefore observed that in order to homogeneously entrain the particles at the heart of the plasma flow, that is to say to ensure that all the particles are effectively entrained at the center of the flow of the plasma jet, ii is necessary not only to adjust the axial and radial positions of the injector relative to said main axis and its inclination relative to an axis perpendicular to said main axis but also to control the average amount of movement of these particles to the orifice of output of this injector.
La Figure 4 montre dans un mode de mise en œuvre particulier la distribution des vitesses moyennes des particules le long de l'axe principal en fonction du courant d'Arc (A). L'axe des abscisses 16 qui représente la position des particules le long de l'axe principai (mm), a pour point d'origine 17 l'extrémité de la source à plasma et l'axe des ordonnées 18 représente la vitesse moyenne des particules (m/s). Les poudres utilisées sont des particules d'alumine et la source à plasma est une torche plasma AQTIL. La première courbe Si (losange) est obtenue pour un courant d'Arc de 450 A, la deuxième courbe S2 (rectangle) est obtenue pour un courant d'Arc de 310 A et la troisième courbe S3 (triangle) est obtenue pour un courant d'Arc de 180 A. Il ressort de ces courbes que les particules présentent des phases d'accélération et de décélération et que la position axiale 19 du maximum de la vitesse moyenne des particules pour un courant d'Arc donné se déplace vers l'aval de la torche avec l'augmentation du courant d'arc. La distance D de l'extrémité de la source de plasma à laquelle les particules acquièrent une vitesse moyenne maximale est donc bien variable en fonction du courant d'arc appliqué. Il est nécessaire de déterminer cette position pour la caractérisation des échantillons dans des conditions aussi réelles que possible. On observe également que la vitesse moyenne maximale des particules est approximativement quatre fois plus éievée à 450 A (420 +/- 45 m/s) qu'à 180 A (125 +/- 15 m/s). On peut donc ajuster la vitesse moyenne maximaie des particules en ajustant la vitesse du jet de plasma par augmentation de la puissance électrique de fonctionnement de la source de plasma.Figure 4 shows in a particular implementation mode the distribution of average particle velocities along the main axis as a function of the arc current (A). The abscissa axis 16, which represents the position of the particles along the principal axis (mm), has as its point of origin 17 the end of the plasma source and the ordinate axis 18 represents the average speed of the particles (m / s). The powders used are particles of alumina and the plasma source is an AQTIL plasma torch. The first curve Si (diamond) is obtained for a current of 450 A arc, the second curve S 2 (rectangle) is obtained for an arc current of 310 A and the third curve S 3 (triangle) is obtained for 180 A arc current. These curves show that the particles have acceleration and deceleration phases and that the axial position 19 of the maximum of the average particle velocity for a given arc current moves towards the downstream of the torch with the increase of the arc current. The distance D from the end of the plasma source at which the particles acquire a maximum average speed is therefore very variable as a function of the applied arc current. It is necessary to determine this position for the characterization of samples under conditions as real as possible. It is also observed that the average maximum particle velocity is approximately four times higher at 450 A (420 +/- 45 m / s) than at 180 A (125 +/- 15 m / s). We can therefore adjust the maximum average speed of particles by adjusting the speed of the plasma jet by increasing the electrical operating power of the plasma source.
Avantageusement, l'invention peut être mise en œuvre comme dispositif de pulvérisation thermique de particules pour le dépôt de revêtements, par exemple métalliques, sur une surface. Advantageously, the invention can be implemented as a device for thermal spraying of particles for the deposition of coatings, for example metal, on a surface.
Claims
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP06726217.0A EP1867220B1 (en) | 2005-03-17 | 2006-03-03 | Method and device for generating a thermal flux loaded with particles |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR0550693 | 2005-03-17 | ||
| FR0550693A FR2883411B1 (en) | 2005-03-17 | 2005-03-17 | METHOD AND DEVICE FOR GENERATING A THERMAL FLOW CHARGED WITH PARTICLES |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2006097649A1 true WO2006097649A1 (en) | 2006-09-21 |
Family
ID=35058539
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/FR2006/050193 Ceased WO2006097649A1 (en) | 2005-03-17 | 2006-03-03 | Method and device for generating a thermal flux loaded with particles |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP1867220B1 (en) |
| FR (1) | FR2883411B1 (en) |
| RU (1) | RU2404552C2 (en) |
| WO (1) | WO2006097649A1 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3060693A4 (en) * | 2013-10-25 | 2016-11-16 | United Technologies Corp | PLASMA SPRAY SYSTEM WITH ADJUSTABLE COATING MEDIUM NOZZLE |
| CN108387361A (en) * | 2016-10-08 | 2018-08-10 | 哈尔滨理工大学 | Array air blowing type aero-optical effect simulator |
| CN108426695A (en) * | 2017-12-14 | 2018-08-21 | 中国航天空气动力技术研究院 | A kind of hypersonic N-S equations observation procedure |
| DE102018210115A1 (en) * | 2018-06-21 | 2019-12-24 | Siemens Aktiengesellschaft | Adjustable injector holder for setting the spray spot during thermal coating and processing |
| DE102023111775A1 (en) * | 2023-05-05 | 2024-11-07 | Elringklinger Ag | Method, system and use for determining the resistance of a material and/or a test specimen |
| CN120160788A (en) * | 2025-03-24 | 2025-06-17 | 中国航天空气动力技术研究院 | A method for establishing a low NOx plasma jet with simulated air components |
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|---|---|---|---|---|
| GB1492860A (en) * | 1974-09-03 | 1977-11-23 | Cockerill | Device for distributing a metallic powder in a flame for applying a metallic coating |
| DE3435748A1 (en) * | 1984-09-28 | 1986-04-10 | Siemens AG, 1000 Berlin und 8000 München | Method and device for coating workpieces by means of thermal spraying, in particular by plasma spraying |
| US5047612A (en) * | 1990-02-05 | 1991-09-10 | General Electric Company | Apparatus and method for controlling powder deposition in a plasma spray process |
| US5233153A (en) * | 1992-01-10 | 1993-08-03 | Edo Corporation | Method of plasma spraying of polymer compositions onto a target surface |
| US6478234B1 (en) * | 2001-06-18 | 2002-11-12 | Northrop Grumman Corporation | Adjustable injector assembly for melted powder coating deposition |
| US20040013813A1 (en) * | 2000-05-23 | 2004-01-22 | Erich Lugscheider | Materials and method for producing a corrosion and abrasion-resistant layer by thermal spraying |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| RU2092981C1 (en) * | 1996-05-29 | 1997-10-10 | Закрытое акционерное общество "Технопарк ЛТА" | Plasma generator for deposition of powder materials |
| RU2220518C1 (en) * | 2002-05-29 | 2003-12-27 | Федеральное государственное унитарное предприятие Научно-исследовательский институт комплексных испытаний оптико-электронных приборов и систем | Method and device for producing microparticle flux |
-
2005
- 2005-03-17 FR FR0550693A patent/FR2883411B1/en not_active Expired - Fee Related
-
2006
- 2006-03-03 EP EP06726217.0A patent/EP1867220B1/en not_active Not-in-force
- 2006-03-03 WO PCT/FR2006/050193 patent/WO2006097649A1/en not_active Ceased
- 2006-03-03 RU RU2007138508/06A patent/RU2404552C2/en not_active IP Right Cessation
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1492860A (en) * | 1974-09-03 | 1977-11-23 | Cockerill | Device for distributing a metallic powder in a flame for applying a metallic coating |
| DE3435748A1 (en) * | 1984-09-28 | 1986-04-10 | Siemens AG, 1000 Berlin und 8000 München | Method and device for coating workpieces by means of thermal spraying, in particular by plasma spraying |
| US5047612A (en) * | 1990-02-05 | 1991-09-10 | General Electric Company | Apparatus and method for controlling powder deposition in a plasma spray process |
| US5233153A (en) * | 1992-01-10 | 1993-08-03 | Edo Corporation | Method of plasma spraying of polymer compositions onto a target surface |
| US20040013813A1 (en) * | 2000-05-23 | 2004-01-22 | Erich Lugscheider | Materials and method for producing a corrosion and abrasion-resistant layer by thermal spraying |
| US6478234B1 (en) * | 2001-06-18 | 2002-11-12 | Northrop Grumman Corporation | Adjustable injector assembly for melted powder coating deposition |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3060693A4 (en) * | 2013-10-25 | 2016-11-16 | United Technologies Corp | PLASMA SPRAY SYSTEM WITH ADJUSTABLE COATING MEDIUM NOZZLE |
| US10793941B2 (en) | 2013-10-25 | 2020-10-06 | Raytheon Technologies Corporation | Plasma spraying system with adjustable coating medium nozzle |
| CN108387361A (en) * | 2016-10-08 | 2018-08-10 | 哈尔滨理工大学 | Array air blowing type aero-optical effect simulator |
| CN108426695A (en) * | 2017-12-14 | 2018-08-21 | 中国航天空气动力技术研究院 | A kind of hypersonic N-S equations observation procedure |
| CN108426695B (en) * | 2017-12-14 | 2020-08-14 | 中国航天空气动力技术研究院 | Hypersonic three-dimensional shock wave structure observation method |
| DE102018210115A1 (en) * | 2018-06-21 | 2019-12-24 | Siemens Aktiengesellschaft | Adjustable injector holder for setting the spray spot during thermal coating and processing |
| DE102023111775A1 (en) * | 2023-05-05 | 2024-11-07 | Elringklinger Ag | Method, system and use for determining the resistance of a material and/or a test specimen |
| CN120160788A (en) * | 2025-03-24 | 2025-06-17 | 中国航天空气动力技术研究院 | A method for establishing a low NOx plasma jet with simulated air components |
Also Published As
| Publication number | Publication date |
|---|---|
| RU2007138508A (en) | 2009-04-27 |
| FR2883411B1 (en) | 2007-06-15 |
| RU2404552C2 (en) | 2010-11-20 |
| FR2883411A1 (en) | 2006-09-22 |
| EP1867220B1 (en) | 2015-02-25 |
| EP1867220A1 (en) | 2007-12-19 |
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