FR2495229A1 - DOUBLE OPEN FUEL INJECTION NOZZLE FOR GAS TURBINE ENGINE - Google Patents

Abstract

The present invention relates to a double-opening fuel injection nozzle. The injection nozzle is designed to reduce pollutant emissions and minimize carbon formation in the secondary fuel passage of a double-opening injection nozzle for the combustion chamber of a gas turbine engine. The openings and passages for air and fuel are sized to increase the pressure in the secondary passage during the time when it is inoperative and when the main fuel only passage is operational and the air and fuel exiting at the both primary and secondary ports swirl in the same direction. The invention is, for example, usable in gas turbine engines. (CF DRAWING IN BOPI)

Description

1-

  The present invention relates to injection nozzles

  turbine type engine fuel and, in particular,

  double-opening nozzles and a device to improve the quality of gas emissions. From an ecological point of view and government requirements for the reduction of pollutants entering the atmosphere, a concerted effort has been made to improve the quality of engine exhaust

airline.

  One of the main areas that is commonly explored is the combustion load of the engines and their

associated injection nozzle.

  The purpose of the present invention is to reduce

  emissions from aircraft gas turbine engines.

  In particular, it has been found that by some modifications on existing fuel injection nozzles it is possible to significantly reduce the emissions of pollutants. For this purpose, the vortex is selected so that both air and / or fuel when

  out of the combustion zone are in the same direction.

  An essential feature of the present invention

  It is intended to provide an injection nozzle of the type comprising main and secondary fuel supply openings for a combustion chamber of a gas turbine engine to impart a swirl to the fuel and to the fuel.

the air in the same direction.

  A preferred feature of the invention is to carefully select the value of the surface ratio of the air inlet and the fuel / air outlet to obtain a positive pressure inside the nozzle with respect to the pressure in the nozzle. the combustion zone of the combustion chamber in combination with fuel and

air rico-rotation.

  The output of fuel and co-rotating air in the combustion zone of the combustion chamber reduces

  emissions of hydrocarbons, NOx, and carbon monoxide

born.

  It has been found that the essential discovery of the

  vention is also particularly advantageous in relation

  with the injection nozzle provided with an injection device

  water. As is well known, engine thrust can be increased by adding water to the burner section. In the fuel injection nozzles for some engines both primary and secondary fuels are injected into the burner in conical spray patterns which are coaxial. Such nozzles are, for example, used in the JT-9D engine manufactured by Pratt & Whitney Aircraft of the United Technologies Corporation group. In this system, water is admitted upstream of the fuel spraying device and passes through the fuel support heat shields prior to being injected into the burner section via the vortex generating devices of the burner section. The problem with this assembly is that a significant deterioration of burner performance has been noted. Also, this type of water injection system showed a high smoke density, produced excessive hot spots at the inlet of the turbine as well as excessive distortions of the radial profile of the inlet temperature.

of the turbine.

  It is also well known that fuel and air are injected into a burner according to a component

  tangentielkÄ so as to obtain a fast and complete mixture.

  Since the water is admitted upstream of the junction where it mixes with the fuel, it is transported in the air flow and acquires the same rotational direction. For this, the fuel injection nozzle comprises slots and swirl blades which are designed to impart a swirling motion to the

  fuel and air. In addition, the injection nozzle

  The design is such that the fuel injection pattern and the air in the combustion zone of the burner have the shape of the cone radiating from the top as it leaves the injection nozzle and flares out at an angle.

  cone when it spreads itself in the burner.

  In the nozzle structures employed so far, it was usual to communicate the swirling motion to the fuel in a sense that is

  opposite to the swirling direction of the air ..

  By changing the ratio of the turn directions

  In such a way that the mixture of fuel and air / water all swirl in the same direction, the tendency of the outer cone (air / water mixture) to crush the internal cone (pulverized fuel) is

  this is the case in rotational swirl

  in the opposite direction and improves the uniformity

  fertigation of the combustion and prevents the formation of localized hot spots that manifest in the turbine. The water in the airflow does not crush the fuel model and does not want to conglomerate into individual flows. Real tests have shown a remarkable decrease in smoke emission during performance under humidity compared to the performances under humiutewater injection systems

known so far.

  In order that the invention may be better understood, reference is made to the following figures or: FIG. 1 is an enlarged view partly in section and partially in elevation showing the

  details of a first embodiment of the invention.

  FIG. 2 is an enlarged view partially in section and partly in elevation showing the details

  of a second embodiment of the invention.

  In its preferred embodiment, the present

  The invention has particular utility for pressurized fuel injection nozzles which include both primary and secondary fuel injection systems. For the details of this type of det

  nozzle, reference is made to the fuel injection nozzles

  used in the JT-8D and JT-9D engines manufactured by Pratt & Whitney Aircraft of the United Technologies Corporation Group. As far as the invention concerns only the fuel injection nozzle, the details of the engine and its combustion chamber fed by these nozzles are eliminated here for convenience and simplicity. Suffice it to say that the engines mentioned above use 4-

  dual-aperture fuel injection nozzles

  taking main pressurized and secondary pressure or air nozzles where the main nozzle is used for both low thrust and high thrust operation and the secondary nozzle is operable only for

high-pressure diets.

  In FIG. 1, the injection nozzle comprises a main fuel supply orifice 12 formed in the main nozzle 14 of generally conical shape and a second fuel supply orifice 16 communicating with the annular passage 18 defined between the element of

  nozzle 20 conically spaced and the main nozzle 14.

  The swirl ring 22 and the tower plug

  24 are used to communicate a tangential speed

  fuel before it enters the

  combustion and produce the illustrated flow model.

  Part of the air from the compressor is admitted into the nozzle nut 26 through the swirl slots 28 and similarly communicates a velocity tangential to the air as it progresses into the combustion zone as shown by the flow model.

  Air is also introduced around the fuel.

  A divisive device 34 may be used as shown. As can be seen, the

  flow model is as it is indicated.

  As will be obvious to these specialists in

  matter, the direction of swirling and the tan-

  are dictated by the blades and cracks of

  billonnement. According to the present invention, both the air

  and the fuel entering the combustion zone

  are in the same direction. The swirl plug 24 and the swirl ring 22 as well as the

  swirl slots 28 and swirl vanes

  32 communicate a swirling motion in a

common direction.

  The pressure inside the secondary injection nozzle upstream of the orifice 16 is higher than the pressure downstream thereof when only

  primary fuel passes. Also in the mode of realization

  In the preferred embodiment, it has been found that good ejection results have been obtained when the annular surface of the discharge port defined between the associated lip 36 of the nozzle nut 26 and the nozzle heat shield 50 is adjusted. injection, and the air of the orifice 36 are

substantially equal.

  To ensure a proper pressure value, the number of swirl slots 28 of the original injection nozzle nut was increased from 8 to 16 for an area of 1.329 cm 2. Real tests on motor realized

  with these modifications compared to injection nozzles

  used so far have shown a reduction

  carbon monoxide, hy-

drocarbureset of NOx.

  The injection nozzle shown in FIG. 2 from all essential points of view is substantially identical to the injection nozzle of FIG. 1. In both FIGS. 1 and 2 the corresponding elements

  are provided with the same reference numbers. The nozzle of in--

  Figure 2 differs only from the injection nozzle of Figure 1 in that the orifice 36 'has a larger area relative to the heat shield 50 of the injection nozzle than in the embodiment of the invention. 1 and devices are provided for the admission of water into the air stream at a given location upstream of the swirling device shown by the inlet 40 and conveyed into the air stream and has swirled with it by the nozzle nut 26 and the

cut 30.

  As can be seen in Figure 2, the meaning

  swirling for both fuel flows

  rant and air / water mixture are in the same direction.

  The rotating rotation aspect serves to prevent droplets

  of water to agglomerate in a localized flow which otherwise

  This would cause distortions in the temperature profile emanating from the combustion section. From actual tests, it has been found that the co-rotating appearance improves the performance of the burner and reduces smoke emissions at the motor outlet in water-injection cases. Naturally, various modifications can be made by those skilled in the art to the apparatuses which have just been described solely as non-limiting examples.

  without departing from the scope of the invention.

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Claims (7)

claims:   1. Double-opening fuel injection nozzle for a combustion chamber of a gas turbine engine comprising a compressor, this injection nozzle having a generally conical shaped casing with a main passage for the fuel arranged centrally therein, a secondary passage for the fuel, formed therein arranged concentrically with respect to the main fuel passage, both the main and secondary passages injecting fuel into said combustion chamber through a plane substantially mutually transversal, a device for communicating   a swirling motion in the air from the compres-   surrounding the fuel coming out of these main and secondary passages, this main fuel passage being normally continuously   period of engine operation, and this sec-   fuel being normally functional only during high-thrust and non-operational regimes - during the low thrust regimes of this   motor operation, a first communication device -   as a swirling motion to fuel in this   main passage to communicate a movement of   fuel billing outgoing, a second device imparting a swirling motion to the fuel in the secondary passage to communicate a swirling motion to the fuel that comes out, characterized in that the first device communicating a movement   swirling, this second device communicating a motion   swirling with fuel and this communication device   as a swirling motion in the air communicates a   swirling motion in a common sense.   2. Double-opening fuel injection nozzle according to claim 1, characterized in that   comprises a device for pressurizing the secondary passage   when the main passage is only operational with this air coming from the compression section, so that this secondary passage maintains a positive pressure to prevent the fuel of this main passage from penetrating into it and charcoal the walls of this secondary passage.   A double-opening type fuel injection nozzle according to claim 2, characterized in that   that this device to communicate a movement of turn-   Billeting air from the compressor includes a nozzle nut mounted at the end of this shaped housing   tapered and having a central opening arranged coaxially   relative to the axial axis of this main passage, -   a dome-shaped heat shield element whose apex is fixed at the top of this conical-shaped housing and a base attached to the base of this conical-shaped housing, annular-shaped walls extending inwardly of this nozzle nut and defining a central opening disposed coaxially with respect to the axis and spaced axially from the top of the dome-shaped element, the central opening of these walls and this space being   dimensioned so that the unloading air of the compres-   it acquires a swirling movement through the passages formed in the base of this nut and unloading through this central opening pressurizes this passage   when the main passage alone is opera-   tional. The dual aperture fuel injection nozzle of claim 1 including a first pass   ring disposed concentrically between this second passage   this main passage and a second annulment   concentrically mounted on and surrounding this secondary passage for supplying air from the compressor in these first and second annular passages to be mixed with the fuel ejected by these main and secondary passages, a device for imparting a swirling motion to the air passing through these first and second annular passages so that the unloading air swirls around this exiting fuel, these first and second annular passages being sized to pressurize this secondary passage when the passage principal only is operational.   5. Double-type fuel injection nozzle   opening according to any one of claims 1 to 4,   characterized in that devices are provided for   inject water just in front of this communi-   as for a movement swirling in the air. 6. Double-opening fuel injection nozzle according to claim 5, characterized in that it comprises a nozzle nut disposed coaxially with respect to the axes of this main passage and this secondary passage, swirl slots in this nut of nozzle for imparting a swirling motion to the air and water in the same direction as the swirling movement of the fuel exiting from that main passage and that secondary passage.   7. Fuel injection nozzle according to the   cation 6, characterized in that it comprises a vortex cutting element of the air surrounding this nozzle nut having vane swirl blades arranged   coaxially with this nozzle nut for communication with   move swirling in air and water in the same direction as the swirling motion of the fuel   coming out of this primary passage and this secondary passage.