RU2353790C1 - Aviation bypass turbojet engine - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: aviation bypass turbojet engine comprises fan, high-pressure compressor, combustion chamber, high and low pressure turbines, mixer and afterburner and nozzle common for both circuits. Downstream the first stage of high-pressure compressor that provides for full pressure increase extent at takeoff regime of not more than π_Iext*=1.4…1.5, permanently open annular channel is arranged with honeycomb straightener, through which at all modes of engine operation, some air is relieved downstream stage into cocurrent flow of air in external circuit downstream fan.

EFFECT: increased extent of engine bypass-ratio and increased efficiency at non-augmented modes of operation.

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Description

Technical field

The invention relates to aircraft engine manufacturing, and in particular to the development and creation, first of all, of aircraft dual-circuit turbojet engines with a mixture of external air flows and gases behind turbines and common afterburner and nozzle (TRDDF), can also be applied in the development of dual-circuit after-engines aircraft ( Turbofan engine), including engines with separate circuits.

State of the art

For supersonic shunting aircraft, a number of fourth and fifth generation turbofan engines were created in Russia (RD-33, AL-31F) and abroad (EJ-200, the M.88, F404, F414, F125 engine family). All these engines are made according to the same scheme that has become traditional, including a low-pressure compressor (fan), a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine, an mixer for the flow of air from the external circuit and internal circuit gases, the afterburner common to both circuits and supersonic nozzle.

The improvement of the parameters and characteristics of engines of this class is, first of all, in the direction of increasing their specific thrust, which, when comparing engines, is evaluated on the take-off afterburning mode -R _udf = R _fvzl / G _v∑ , where R _fvzl and G _v∑ , accordingly, thrust and air flow at the engine inlet in this mode. The specific thrust of the engine at the required value of R _fvzl directly affects its dimension and mass.

Engines of the 70s-80s had R _udf slightly exceeding 1100 N · s / kg, and the F414-GE-400 engine, the development of which dates back to the 90s, has R _udf > 1350 N · s / kg (Information on the listed foreign engines is presented in the TsIAM reference book “Foreign Aircraft Engines”, issue 14, edited by V. A. Skibin and V. I. Solonin. Moscow, ed. Aviamir House, 2005).

The specific thrust of the engine, which is directly proportional to the rate of gas outflow from the nozzle, at the reached maximum temperature levels of the gases in front of the nozzle in the afterburner mode, becomes dependent only on the differential pressure of the gases in the nozzle. In the take-off mode, at close to each other (with a difference of no more than 3%) total pressures of air and gas in the circuits at the outlet of the mixer, the pressure drop across the nozzle is almost directly determined by the total air pressure in the external circuit, i.e. for all conventional turbofan engines used in the traditional scheme, the differential pressure of the gases in the nozzle depends on the degree of increase in air pressure in the fan π _in ^* .

Therefore, an increase in specific engine thrusts from R _udf ≥1100 N · s / kg to R _udf ≥1350 N · s / kg was accompanied by a corresponding increase in π _in *. The F414-GE-400 engine with R _udf ≥1350 N · s / kg also has the highest-pressure fan, providing π _at ^* = 5.0.

где

- полные давления газа и воздуха, соответственно, контурах на выходе из смесителя.However, an increase in π _in ^* leads to the need to reduce the bypass ratio of the engine in the take-off mode (m _о ) to ensure an acceptable ratio of the total pressures in the circuits at the outlet of the mixer

Where

- full pressure of gas and air, respectively, the circuits at the outlet of the mixer.

On the engine F414-GE-400 m _o = 0.29.

A further decrease in the dual-circuit engine brings the dual-circuit engine closer to single-circuit with a corresponding deterioration in its performance in specific fuel consumption in non-cruising cruising modes.

In addition, an increase in π _in ^* increases the loading of the low pressure turbine, which can lead to an increase in the stages of the low pressure turbine.

For example, plans for further development engine F414-GE-400, along with other measures to improve the engine parameters provided _{in the} π ^* increase by 10% and replaced by a single stage low pressure turbine to the two.

The traditional engine schematic, which is the basis for the RD-33, AL-31F, EJ-200 engines and engines of the M.88, F404, F414 and F125 families, is adopted as a prototype.

SUMMARY OF THE INVENTION

This invention solves the problem of expanding the arsenal of tools that increase the specific thrust of the turbofan engine; The technical result consists in the implementation of this purpose.

Salient features:

- Restrictive: an aircraft dual-circuit turbojet engine containing a fan, a high-pressure compressor, a combustion chamber, high-pressure and low-pressure turbines, a mixer, and an afterburner and a nozzle common to both circuits.

- Distinctive: behind the first stage of the high-pressure compressor, which ensures the degree of pressure increase not more than π _Ist ^* = 1.4 ... 1.5 in the take-off mode, an annular channel with a straightening grate is made through which constant part of the air is constantly bypassed at all engine operation modes due to a step in a satellite stream of air of the external circuit behind the fan.

Brief Description of the Drawings

The invention is illustrated by the drawings:

Figure 1 presents a schematic diagram of a dual-circuit turbojet engine with a channel for bypassing part of the air due to the first stage of the high-pressure compressor into the air flow of the external circuit behind the fan.

In Fig.2 presents a diagram of the channel bypass part of the air due to the first stage of the compressor into the outer circuit on a larger scale than in Fig.1.

Figure 3 presents a cylindrical scan of the rectifier lattice in the air bypass channel.

The implementation of the invention

An aircraft dual-circuit turbojet engine contains a fan 1, a high-pressure compressor 2, a combustion chamber 3, a high-pressure turbine 4, a low-pressure turbine 5, a mixer 6, an afterburner 7, and a supersonic nozzle 8.

Behind the first stage 9 of the high-pressure compressor 2, which ensures during takeoff operation the degree of pressure increase is not more than π _Ist ^* = 1.4 ... 1.5, a constantly open annular channel 10 is made with a straightening grill 11 through which part of the air is bypassed due to the first stage 9 of the high pressure compressor 2 into the channel of the outer circuit 12 after the fan 1.

The limitation of the degree of increase in pressure of the first stage 9 of the high-pressure compressor 2 is not more than π _Ist ^* = 1.4 ... 1.5 is introduced to exclude local flow zones with sound speed at the air outlet from the air bypass channel 10 after the stage to the channel of the external circuit 12 behind the fan 1. The straightening grid 11 in the bypass channel 10 provides the axial direction of the passage of the bypassed air into the channel of the outer circuit 12.

The intake of part of the air due to the first stage 9 of the compressor 2 with a higher total pressure than the total pressure in the stream behind the fan 1, provides an increase in the total total pressure in the air flow of the external circuit in front of the mixer 6 and then, respectively, the total total pressure of the inlet gases in the afterburner 7 and in front of the nozzle 8, which increases the pressure drop of the gas in the nozzle and the rate of gas outflow from the nozzle, increasing the specific thrust of the engine.

With the addition of additional air to the external circuit 12 from the bypass channel 10, the overall degree of dual-circuit of the engine increases and its efficiency in non-after-operation modes increases.

Claims (1)

Aircraft dual-circuit turbojet engine containing a fan, a high-pressure compressor, a combustion chamber, high and low pressure turbines, a mixer, and an afterburner and a nozzle common to both circuits, characterized in that behind the first stage of the high-pressure compressor, which ensures a full increase in takeoff pressure not more than π _Ist * = 1.4 ... 1.5, a constantly open annular channel with a straightening grate is made, through which part of the air is _bypassed at all engine operating modes but because of the step into the satellite stream of air of the external circuit behind the fan.

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