Afterburner chamber bypass turbofan engine

 

Afterburner chamber bypass turbofan engine with a mix of streams contains external and separating the contours of the shell and placed in an internal circuit of the flame stabilizer and fuel injectors. Paths communicated between a downstream from the edge of the stabilizer flame at a distance of not less than the width of its shelves. In the afterburner can be installed heat shield, intake of which is placed coaxially between the outer and dividing the shell. In the channel, limited to the separation drum and the heat-shielding screen placed additional fuel injectors. The invention allows to improve traction and expenditure characteristics of the turbojet engine. 1 C.p. f-crystals, 2 Il.

The invention relates to the field of Aero-engine, in particular to the afterburning chambers aviation turbojet engines (turbofans) with mixing flows.

Known afterburner chamber turbofans with mixing of streams containing separating the contours of the shell and placed in an internal circuit of the stabilizers of the flame and the fuel injector (see, for example, the book "the Design and design of aircraft gas turbine engines" mo before the front of the device (i.e., higher flow), resulting in the flame stabilizers partially or completely blown by the second flow (fan) circuit. As is well known (see, for example, the above-mentioned book, S. 447), by increasing the speed of flight increases the bypass ratio of the engine and, accordingly, the rate of flow of air from the second circuit, which leads to an increase of the pressure loss on the stabilizer flame (respectively, for reducing the thrust of the engine) and the deterioration of the terms of stabilizing the combustion of the fuel due to the increased speed and "impoverishment" of the air-fuel mixture in the zone of reverse currents for a slice of the flame stabilizer (especially in the peripheral part thereof). The latter circumstance also leads to reduction of thrust and fuel economy deterioration.

Quantitative assessment carried out by processing the test results engine RD-33 showed that the loss of total pressure in the afterburner increase from 11.2% in the starting conditions up to 17% on mode maximum flight speed, and the speed of rolling stabilizer flame gas flow increases in these conditions,= 0.34 to= 0,71.

The challenge aimed proposed isoline in the afterburner.

The problem is solved due to the fact that in the afterburner turbofans with mixing of streams containing separating the contours of the shell and placed in an internal circuit of the stabilizers of the flame and the fuel injector according to the invention paths communicated between a downstream from the edge of the stabilizer flame at a distance of not less than the width of its shelves. The mixing of the flows of the two circuits is performed downstream from the flame stabilizer, thanks for all modes of engine operation are saved, the conditions for the formation of an air-fuel mixture in the zone of reverse currents and it is possible to avoid increase of the pressure loss on the stabilizer flame by increasing the degree of bypass ratio turbofans.

Optimally work afterburner is provided in the case, when part of the fuel is fed directly into the second flow (fan) circuit, which coaxially between the outer and separating the shells have intake heat shield afterburners, and channel restricted dividing the shell and heat-shielding screen, place additional fuel injectors. This creates the conditions for improved performance turbofans (increase traction and reduce RAS is an increase in the degree of bypass ratio with increasing speed of aircraft flight requires a corresponding increase in the share of fuels, supplied to the peripheral portion of the afterburner.

In Fig.1 schematically shows a longitudinal section of the proposed afterburners turbofans. In Fig. 2 depicts a stabilizer flame. Afterburner chamber turbofans contains located in the flow securinega gas flame stabilizer 1, the fuel injector 2 and the separating paths securinega (1) and fan (2) threads of the shell 3. Slice the separation of the shell 3 (cross section a-a) is located downstream from the edge of the stabilizer 1 (section b-B) in its periphery at a distance not less than the width of its shelves D. Additional nozzles 4 are located directly in the flow of the second (fan) circuit downstream from intake 5 (section b-b) of the heat shield 6. The intake 5 is placed coaxially between the outer and separating the shells 3 and 7, respectively. At the exit of the afterburner posted by jet nozzle 8.

When working turbofans coming from the turbine, the gas mixes with supplied through the fuel injector 2 fuel runs onto the stabilizer flame 1 and ignited at the boundary of the reverse currents 9 (see Fig.2), is mixed with the air flow of the fan circuit. Through located in the second flow (fan) circuit more and 2), the resulting mixture is ignited by the flame front for the stabilizer 1 and burns as it approaches the jet nozzle 8. The location of additional fuel injectors 4 downstream relative to the intake 5 screen 6 prevents the ingress of fuel and its ignition in the cooling channel, i.e. in the space between the outer shell 7 and the screen 6.

Separate supply of afterburner fuel through the fuel injector 2 in the first circuit and the additional nozzles 4 in the second circuit allows to provide optimal for efficient combustion of the fuel distribution in the cross section afterburners when changing the degree of the bypass ratio of the engine (the increased speed of flight is accompanied by an increase in the degree of the bypass ratio of the engine). This optimization will allow you to limit the speed of flight of the aircraft MiG-29 to increase the combustion efficiency of ~ 4%, which corresponds to the increase of thrust turbofans ~ 2,3%.

The reduction of pressure losses will lead to lower specific fuel consumption at cruise flight mode of the aircraft MiG-29 the earth at ~5.1% and further increase thrust at a maximum flight speed of the aircraft at ~2%, i.e. a total increase of thrust will be ~4.3 percent.

2. Afterburner chamber under item 1, characterized in that it contains heat shield, intake of which is placed coaxially between the outer and separating the shells and channel restricted dividing the shell and with a heat shield, placed additional fuel injectors.

 

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