RU2213246C1 - Rocket engine solid-propellant charge igniter - Google Patents

Abstract

FIELD: rocketry. SUBSTANCE: proposed igniter of solid-propellant rocket charge contains housing accommodating weight of igniting composition in polymeric envelope divided by cross partition into sections. Igniter housing is made of material featuring high thermal conductivity. Igniting composition in polymeric envelop is placed into cotton cloth envelope. Housing of igniter is made of steel. Percale is used as cotton cloth. Polyethylene terephthalate film laminated with polyethylene is used as polymeric film. EFFECT: reduced starting pressure peaks, improved efficiency and reliability of engine. 2 cl, 5 dwg

Description

 The invention relates to the field of rocket technology and can be used in the design, development and manufacture of igniters for solid propellant charges of rocket engines (RD), gas generators (GG) of pressure powder accumulators, etc.

 A known design of an igniter containing a degressively burning charge in a toroidal housing mounted on a heat-shielding coating of a nozzle recessed into the engine (US patent 3729935).

 Known igniters for mortar shots, hitch ignition composition of which is placed in the cap of the fabric material, made in the form of a ring.

 Designs of igniters in aluminum cases are widely used: US patents 3151447, France 2151495.

 A common drawback of these designs is that the ignition of the sample in them occurs extremely quickly throughout the volume, which causes an initial pressure peak in the engine to overshoot and negatively affects the operation of the taxiway (in terms of strength), especially at extreme plus operating temperatures.

 Ignition device designs are known in which two ignitors (or an ignitor divided into two compartments) are used to eliminate pressure spikes at high temperatures, which contain a pyrotechnic composition (US Pat. Nos. 3,731,629, 3,228,191). At low (negative) temperatures, both igniters fire in these devices (or a sample of the igniter in both compartments), and at high (positive) temperature one igniter and, accordingly, one igniter or one weighed.

 A self-regulating igniter is known according to US patent 3324656, where the supply of combustion products to the surface of the charge is regulated depending on the temperature using a rotating ring.

 Some of these analogues provide a certain degree of elimination of pressure spikes from the rapid combustion of the entire igniter sample, but they are quite complex in design and laborious in execution.

 Closest to patentable is the design of the igniter according to the patent of Russia 2170842, adopted by the authors for the prototype.

 Common similar features of the prototype and the claimed design are the use of a polymer film in the igniter shell and the implementation of the igniter in a multi-sectional manner.

 The disadvantage of the prototype is the impossibility of organizing a smooth (normalized) exit of the taxiway to the operating mode with a minimum pressure drop in the initial period. Separate sections of the prototype igniter are easily burned by the k-phase of the electric igniter and the combustion products of neighboring sections, which leads to almost simultaneous combustion of the entire igniter composition. The consequence of this is a significant initial pressure peak, which leads to an increased thickness of the engine chamber and a decrease in its efficiency (weight excellence) in the rocket, as well as possible cases of charge extinction due to a sharp pressure drop after the peak.

 A decrease in the weight of the igniter composition to exclude pressure spikes from the igniter at high temperatures leads to a decrease in the reliability of ignition of the charge at low (negative) temperatures.

 The technical result of the invention is to increase the reliability of the rocket engine by reducing the initial peak pressure from the igniter and increase the time it affects the charge, which allows for stable and reliable ignition of the charge, increase the technical efficiency of the rocket engine (gas generator) and improve the overall dimensions of the rocket (projectile) gas generator) in general.

 The specified technical result is achieved as follows.

 The ignitor of the solid propellant charge of a rocket engine contains a housing with a hint of igniter composition in it in a polymer shell, divided by cross jumpers into sections. The igniter body is made in the form of a toroidal ring from a material with high thermal conductivity. The igniter composition in the polymer shell is additionally placed inside the shell of cotton fabric. The igniter body is made of steel. As the cotton fabric used percale fabric. A polyethylene terephthalate film laminated with polyethylene was used as a polymer film.

 The technical result of the patented invention can be achieved by executing the housing in the form of an open ring, including arc-shaped, and in the form of an extended tube placed, for example, in the charge channel. In this case, the cross-sectional profile of the hull can be made of arbitrary shape (rectangular, circular, elliptical, trapezoidal, etc.), taking into account the optimal layout in a specific rocket energy source (rocket engine, gas generator, etc.).

 The invention is illustrated by the following graphic materials.

Figure 1 - General view of the design of the igniter:
1 - case;
2 - igniter hitch;
3 - polymer shell;
4 - tissue (percale) shell.

 FIG. 2 is a pressure-time diagram using a percale shell.

 FIG. 3 is a pressure-time diagram using a shell of a polymer film.

 4 is a pressure-time diagram when using a combination shell at a positive temperature.

 5 is a pressure-time diagram when using a combination shell at negative temperature.

In FIG. 2-5 are indicated: p - pressure, t - time, T - initial charge temperature during testing, p _max - maximum pressure.

 The igniter contains a housing (1) in the form of a toroidal ring formed by the bottom and cover, made of a heat-resistant material with high thermal conductivity, for example, steel, a hitch (2) of igniter composition, enclosed in a shell (3) of a polymer film and a shell (4) of fabric material, divided by transverse jumpers (5) into sections. In this design of the igniter, the gases generated from the combustion of the sample in one of the sections (ignition of which is made from the igniter) pass between the inner surface of the igniter body and the outer surface of the shells of the subsequent sections, in which the rest of the igniter composition is located.

 Since the igniter body is made of a heat-resistant material with high thermal conductivity, the gases, reaching each subsequent section, cool more intensively, giving part of the thermal energy to the body.

 The placement of the ignition sample in sections in a combined shell of a layer of fabric material and a layer of a polymer film makes it difficult to ignite it from the outer surface with gases from the previous sections. The fabric layer protects the shell from the polymer film from premature opening with a mixture of gases and solid particles, and, due to the presence in the combined shell of the layer from the polymer film and more intensive cooling of the gases entering each subsequent section, the composition ignites in sections sequentially, with a time shift , which actually reduces pressure build-up in comparison with igniter designs, in which the sample burns quickly throughout the volume.

 At the same time, due to the sequential actuation of the igniter sections with a time shift, igniting gases in this case act on the charge for a longer time, which contributes to the reliability of ignition.

An example of a specific embodiment of a patented igniter design:
- toroidal annular steel casing with overall diameter of 160 mm:
- igniter hitch - 150 g of smoky gunpowder;
- the material of the polymer shell is a polyethylene terephthalate film laminated with polyethylene 60 μm thick;
- fabric sheath material - percale;
- number of sections - 5.

 During the fire bench tests as part of the engine, the operation of the igniter was confirmed when igniting a charge of solid rocket fuel from ballistic fuel weighing 7.5 kg.

The effectiveness of the invention was evaluated by comparative fire tests as part of a bench engine:
- chart "pressure-time" when testing the taxiway with an igniter in a single-layer shell of percale tissue (figure 2);
- diagram "pressure-time" with an igniter from a polymer film (figure 3);
- pressure-time diagram with an igniter, in which a sample of the igniter composition is enclosed in a polymer film placed inside a cap made of cotton fabric (percale), divided into sections (Fig. 4).

 As can be seen from the diagrams shown in FIGS. 2-4, the pressure peak overflow is significantly reduced when using the igniter of the patented design (diagram of FIG. 4).

 In FIG. 5 shows a pressure-time diagram for testing an engine of the inventive design of an igniter at a negative temperature, which indicates reliable ignition of the charge.

Claims (2)

 1. The igniter of the solid propellant charge of a rocket engine, comprising a housing with a hinge of igniter composition in a polymer shell, divided by transverse jumpers into sections, characterized in that the igniter housing is made of a material with high thermal conductivity, and the igniter composition in the polymer shell is placed inside the shell is made of cotton fabric, while the case is made of steel, percale fabric is used as cotton fabric, and as a polymer film and - polyethylene terephthalate film laminated with polyethylene.  2. The ignitor according to claim 1, characterized in that the casing is made in the form of a toroidal ring.

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