CN118188557A

CN118188557A - Aeroengine anti-surge system and aeroengine anti-surge method

Info

Publication number: CN118188557A
Application number: CN202410370452.2A
Authority: CN
Inventors: 肖璆; 葛严; 吴仕钰; 邵春雷; 吴琼
Original assignee: Hunan Aviation Powerplant Research Institute AECC
Current assignee: Hunan Aviation Powerplant Research Institute AECC
Priority date: 2024-03-28
Filing date: 2024-03-28
Publication date: 2024-06-14

Abstract

The invention provides an aero-engine anti-surge system and an aero-engine anti-surge method, wherein the aero-engine anti-surge system comprises a gas compressor, a gas release valve, an anti-surge gas release valve and a pre-rotation gas flow generator, wherein the gas compressor is suitable for introducing gas flow; one port of the air release valve is communicated with the air flow in the air compressor; the anti-asthma air release valve is communicated with the air release valve to prevent asthma air release; the pre-rotation air flow generator is communicated with the air release valve and is configured to send pre-rotation air flow to the air inlet of the air compressor after the air release valve is used for air inflow so as to change the pre-rotation amount of main air flow at the inlet of the air compressor. The adjustable pre-rotation air flow is introduced into the inlet air flow to change the pre-rotation amount of the inlet of the compressor, so that the attack angle of the inlet air flow of the first-stage rotor blade is restored to a value close to the design state, and the air flow separation on the blade back is eliminated, thereby avoiding the occurrence of the surge phenomenon.

Description

Aeroengine anti-surge system and aeroengine anti-surge method

Technical Field

The invention relates to the technical field of engines, in particular to an aero-engine anti-surge system with an air inlet pre-rotation autonomous adjustment function and an aero-engine anti-surge method.

Background

Aeroengine compressor surge is a problem that multi-stage compressors are required to face. The reason for multi-stage compressor surge is that the flow capacity of the front and rear booster stages of the compressor is not matched when the engine is operating in an off-design condition. The concrete steps are as follows:

The compressor of modern large turbofan engines is typically a multistage axial flow compressor, and when operated at a deviation from the design speed (typically the normal operating maximum speed), the axial speed drops of several stages before and after and the rim speed drops disproportionately. The axial velocity of the preceding stages drops faster than the rim velocity, causing the positive angle of attack of the gas flow to be too great into an unstable state, the gas separating at the trailing edge of the blade back and possibly diffusing throughout the cascade channels; the axial velocity of the latter stages drops slower than the rim velocity, causing the negative angle of attack of the airflow to be too great and enter a choked condition. When surge occurs, the working blades have no capability to overcome the higher back pressure, air cannot flow back normally in the compressor, the flow rate is increased after being suddenly reduced, the total inlet pressure and the flow rate of the compressor are greatly fluctuated, the rotating speed is unstable, and low-sediment noise or blasting sound can be generated sometimes. If not handled in time, engine stall may result or blade damage due to severe vibration and exhaust temperature increase.

For a medium-sized and small-sized aviation turboshaft engine or a turboprop engine, a compressor rotor assembly is usually a single-stage rotor and consists of a front multistage axial compressor and a rear single-stage centrifugal compressor, wherein the circulation efficiency of the centrifugal compressor is lower than that of the axial compressor before the rotation speed of the compressor is a certain high rotation speed (assumed to be N); after the rotating speed of the air compressor exceeds the high rotating speed N, the circulation efficiency of the centrifugal air compressor is higher than that of the axial flow air compressor. Similarly, the design speed is usually the normal maximum speed, and when the design speed deviates greatly, the axial flow compressor of the previous stages may enter an unstable state, and the centrifugal compressor generally enters a blocking state first, so that surging is caused.

In order to improve the working characteristics of the compressor and expand the stable working range, the modern high-supercharging-ratio compressor is provided with an anti-surge device. For a single-rotor engine, the anti-surge scheme can be divided into two categories of direct deflation of a deflation mechanism and variable camber guide vanes of an inlet of a compressor (or an axial-flow compressor of the previous stages). For example, the following two schemes:

Scheme one: in order to prevent the compressor from surging at a low rotating speed, the intermediate stage direct air release scheme needs to release and split air flow after the intermediate stage of the compressor at the low rotating speed and stops releasing air at a high rotating speed so as to ensure that the engine can meet corresponding performance and power requirements. When the air release valve is opened, the air inflow of the previous stage is increased, the axial speed of the air flow is increased, and the positive attack angle is reduced; the latter stage air flow decreases, the air flow axial velocity decreases, and the negative angle of attack increases.

Scheme II: the adjustable inlet guide vane adopts a rotatable guide vane or a deflection guide vane before the inlet of the compressor or the front stages of compressors. When the compressor works in an off-design state, the tail of the inlet deflection guide vane is twisted by an angle, so that the pre-rotation amount of the inlet of the compressor is correspondingly changed. Therefore, the attack angle of the air flow at the inlet of the first-stage rotor blade can be restored to a value close to the design state, the air flow separation on the blade back is eliminated, and the surge phenomenon is avoided.

The modern aero-engine generally needs to adopt the two schemes simultaneously to achieve satisfactory anti-asthma effect. However, in the two schemes, the first scheme is to put the pressurized air into the atmosphere, so that the efficiency of the air compressor is reduced, the output power of the engine is reduced, the exhaust temperature is improved, and the second scheme is to add a set of control executing mechanism, so that the structure and the control strategy are complex, the design and manufacturing requirements are high, and the cost is high.

Disclosure of Invention

Therefore, the technical problems to be solved by the invention are that in the aeroengine anti-surge scheme in the prior art, the pressurized air is put into the atmosphere, the efficiency of a gas compressor is reduced, the output power of the engine is reduced, the exhaust temperature is improved, the structure and the control strategy are complex, the design and manufacturing requirements are high, and the cost is high.

To this end, the invention provides an aero-engine anti-surge system comprising:

A compressor adapted to receive a flow of gas therein;

The air release valve is provided with a port communicated with the air flow in the air compressor;

the anti-asthma air release valve is communicated with the air release valve to prevent asthma air release;

further comprises:

And the pre-rotation air flow generator is communicated with the inside of the air release valve or the air compressor and is configured to send pre-rotation air flow to the air inlet of the air compressor after air is introduced into the air release valve or the air compressor so as to change the pre-rotation amount of main air flow at the inlet of the air compressor.

Optionally, the degree of pre-swirl flow compensation to the main flow is proportional to the degree of decrease in the main flow velocity.

Optionally:

In the process of converting the impeller from a large rotating speed state to a small rotating speed state, the main air flow speed is reduced to be A, and the pre-rotation direction speed generated by the pre-rotation air flow is a;

when the main air flow speed is lower than A, the pre-spinning direction speed generated by the pre-spinning air flow is higher than a;

When the main air flow speed is lower than A, the pre-rotation direction speed generated by the pre-rotation air flow is lower than a.

Optionally, the device further comprises an air flow adjusting device connected between the air release valve and the pre-spinning air flow generator for adjusting the compensation degree of the pre-spinning air flow to the main air flow.

Optionally, the air compressor comprises a centrifugal air compressor and an axial flow air compressor, the axial flow air compressor is arranged at the air inlet end, and the air release valve is communicated between the centrifugal air compressor and the axial flow air compressor.

An aero-engine anti-surge method is used for the aero-engine anti-surge system, when the rotating speed of the aero-engine is reduced, a pre-swirl air flow generator is used for feeding the pre-swirl air flow into an air inlet of a compressor, so that the inlet attack angle is maintained to be in accordance with a design state.

Optionally, the method comprises;

setting the main air flow direction as an axial direction X, and setting the pre-rotation speed direction generated by the pre-rotation air flow as an impeller rotation direction Y;

When the air inlet is in a high rotating speed state, the relative speed is w1, the attack angle of the inlet air flow is in a design state, and the connection speed is u1; at the moment, the axial speed of the main air flow is C1 x, and the pre-spinning direction speed generated by the pre-spinning air flow is C1y;

when the rotating speed is reduced to a small rotating speed state, the traction speed u1 is reduced to a traction speed u2, the main air flow speed is reduced to C2x, the pre-spinning direction speed generated after the pre-spinning air flow and the main air flow are converged is C2y, and the relative speed at the moment is w2;

the vectors w1 and w2 are the same, and the compensation degree of the pre-rotation air flow to the main air flow is in direct proportion to the reduction degree of the speed of the main air flow, so that the attack angle of the inlet air flow is kept in a design state under a small rotating speed state.

Optionally:

the main air flow speed is slowly reduced to A, and C1y is approximately equal to C2y;

when the main air flow speed is lower than A, C1y is less than C2y;

when the main air flow speed is lower than A, C1y > C2y.

Alternatively, w1 and w2 are positively correlated with the airflow angle of attack, and u1 and u2 are positively correlated with the impeller speed.

The aero-engine anti-surge system and the aero-engine anti-surge method provided by the invention have the following advantages:

The invention provides an aero-engine anti-surge system, which comprises a gas compressor, a gas release valve, an anti-surge gas release valve and a pre-rotation gas flow generator, wherein the gas compressor is internally suitable for introducing gas flow; one port of the air release valve is communicated with the air flow in the air compressor; the anti-asthma air release valve is communicated with the air release valve so as to prevent asthma air release; the pre-rotation air flow generator is communicated with the air release valve and is configured to send pre-rotation air flow to the air inlet of the air compressor after the air release valve is used for air inflow so as to change the pre-rotation amount of main air flow at the inlet of the air compressor.

The aero-engine anti-surge system with the structure can change the pre-rotation amount of the main air flow at the inlet of the air compressor by introducing the pre-rotation air flow. When the pre-rotation air flow is not introduced, the axial speed of the front and rear stages is reduced and the rim speed is reduced disproportionately when the pre-rotation air flow is operated at a deviation from the designed rotating speed (the rotating speed is reduced); the axial velocity of the preceding stages drops faster than the rim velocity, causing the positive angle of attack of the gas flow to be too great into an unstable state, the gas separating at the trailing edge of the blade back and possibly diffusing throughout the cascade channels; that is, when the rotational speed is reduced, the intake air flow is reduced more rapidly than the rim speed, resulting in an excessive positive angle of attack of the intake air. For this purpose, by introducing an air flow regulating device and a pre-swirl air flow generator, the pre-swirl effect of the pre-swirl air flow on the intake main air flow can be varied according to a predetermined law when the rotational speed is reduced. When the rotating speed is reduced, the reducing speed of the main air flow of the air inlet is faster than the reducing speed of the wheel rim, but the change rule of the pre-spinning effect of the pre-spinning air flow can compensate the result that the positive attack angle of the air inlet is overlarge due to the fact that the air flow speed is reduced too fast, so that the requirement of maintaining the attack angle of the air inlet to be close to the design state is met.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of an aircraft engine anti-surge system provided in an embodiment of the present invention;

FIG. 2 is a schematic illustration of an air intake pre-rotation adjustment of an aero-engine anti-surge system provided in an embodiment of the present invention;

FIG. 3 is another schematic view of an aircraft engine anti-surge system provided in an embodiment of the present invention.

Reference numerals illustrate:

1-a centrifugal compressor;

2-an axial compressor;

3-a deflation valve;

4-an anti-asthma air release valve;

5-a pre-swirl flow generator;

6-air flow regulating device.

Detailed Description

The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.

Example 1

At present, the surge of an aeroengine compressor is a difficult problem which needs to be faced by a multistage compressor. The reason for multi-stage compressor surge is that the flow capacity of the front and rear booster stages of the compressor is not matched when the engine is operating in an off-design condition. The concrete steps are as follows: when operating at speeds deviating from the design speed, the axial speed drop and the rim speed drop of the preceding and following stages are disproportionate. The axial velocity of the preceding stages drops faster than the rim velocity, causing the positive angle of attack of the gas flow to be too great into an unstable state, the gas separating at the trailing edge of the blade back and possibly diffusing throughout the cascade channels; the axial velocity of the latter stages drops slower than the rim velocity, causing the negative angle of attack of the airflow to be too great and enter a choked condition. When surge occurs, the working blades have no capability to overcome the higher back pressure, air cannot flow back normally in the compressor, the flow rate is increased after being suddenly reduced, the total inlet pressure and the flow rate of the compressor are greatly fluctuated, the rotating speed is unstable, and low-sediment noise or blasting sound can be generated sometimes. If not handled in time, engine stall may result or blade damage due to severe vibration and exhaust temperature increase.

At present, the modern high-supercharging-ratio air compressors are all provided with anti-surge devices, and the anti-surge scheme can be divided into two categories, namely a direct air discharge mechanism for discharging air and a variable camber guide vane at an inlet of the air compressor (or a front-stage axial-flow air compressor). The air discharge mechanism directly discharges air after pressurization into the atmosphere, so that the efficiency of the air compressor is reduced, the output power of the engine is reduced, and the exhaust temperature is increased; the variable camber guide vane at the inlet of the air compressor has complex structure and control strategy, high design and manufacturing requirements and higher cost.

Therefore, the embodiment provides the aero-engine anti-surge system, which not only can reduce the anti-surge bleed flow requirement and improve the efficiency of the air compressor and the performance of the engine, but also can simplify the structure and reduce the cost.

Referring to fig. 1, fig. 1 is a schematic diagram of an aircraft engine anti-surge system. In the embodiment shown in fig. 1, the aero-engine anti-surge system comprises a compressor, a bleed valve 3, an anti-surge bleed valve 4, a pre-swirl flow generator 5 and a flow regulating device 6.

In the embodiment shown in fig. 1, the compressor is suitable for introducing air flow, the compressor comprises a centrifugal compressor 1 and an axial flow compressor 2, the axial flow compressor 2 is arranged at an air inlet end, and one port of a gas release valve 3 is communicated with the air flow in the compressor and is communicated between the centrifugal compressor 1 and the axial flow compressor 2; the anti-asthma air release valve 4 is communicated with the air release valve 3 to perform anti-asthma air release; a pre-swirl flow generator 5 in communication with the bleed valve 3 and configured to deliver a pre-swirl flow to the compressor inlet after inlet through the bleed valve 3 to vary the pre-swirl amount of the compressor inlet main flow; an air flow regulating device 6 is connected between the bleed valve 3 and the pre-swirl flow generator 5 to regulate the degree of pre-swirl flow compensation to the main air flow.

When the engine is at a low rotation speed, the air release valve 3 is opened, a part of P2.5 air flows to the atmosphere, and a part of P2.5 air passes through the air flow regulating device 6 and then generates pre-spinning air flow through the pre-spinning air flow generator 5, and the pre-spinning air flow is combined with the air inlet main air flow and is pre-spun. The pre-swirl flow reduces the positive inlet angle of attack of the compressor inlet air prior to entering the first stage compressor. When the engine speed increases, both the intake air flow speed and the impeller speed change, and although the intake air flow decreases faster than the rim speed (resulting in an excessive positive intake attack angle), the pre-swirl effect after the main air flow and the pre-swirl air flow meet can be compensated, so that the intake attack angle can be maintained near the design state all the time. The air release valve 3 can be opened to simultaneously realize the functions of preventing asthma and air release and pre-rotation of air inflow, and when the rotation speed of the engine is increased to a set degree, the air release valve 3 is closed, and the anti-asthma system does not work.

In this embodiment, the degree of pre-swirl flow compensation to the main flow is proportional to the degree of decrease in the main flow velocity. Specifically, for example, in the process of converting the impeller from a large rotating speed state to a small rotating speed state, the main air flow speed is a, and the pre-rotation direction speed generated by the pre-rotation air flow is a; when the main air flow speed is lower than A, the pre-rotation direction speed generated by the pre-rotation air flow is higher than a; when the main air flow speed is reduced to be less than A, the pre-spinning direction speed generated by the pre-spinning air flow is less than a.

The invention can change the pre-rotation amount of the main air flow at the inlet of the compressor by introducing the pre-rotation air flow. When the pre-rotation air flow is not introduced, the axial speed of the front and rear stages is reduced and the rim speed is reduced disproportionately when the pre-rotation air flow is operated at a deviation from the designed rotating speed (the rotating speed is reduced); the axial velocity of the preceding stages drops faster than the rim velocity, causing the positive angle of attack of the gas flow to be too great into an unstable state, the gas separating at the trailing edge of the blade back and possibly diffusing throughout the cascade channels; that is, when the rotational speed is reduced, the intake air flow is reduced more rapidly than the rim speed, resulting in an excessive positive angle of attack of the intake air. For this purpose, by introducing the air flow regulating device 6 and the pre-swirl air flow generator 5, the pre-swirling effect of the pre-swirl air flow on the intake main air flow can be varied according to a predetermined law when the rotational speed decreases. When the rotating speed is reduced, the reducing speed of the main air flow of the air inlet is faster than the reducing speed of the wheel rim, but the change rule of the pre-spinning effect of the pre-spinning air flow can compensate the result that the positive attack angle of the air inlet is overlarge due to the fact that the air flow speed is reduced too fast, so that the requirement of maintaining the attack angle of the air inlet to be close to the design state is met.

By way of illustration in fig. 2, fig. 2 is a schematic illustration of an air intake pre-rotation adjustment of an aircraft engine anti-surge system. Assuming that the main air flow direction of the air intake is the axial direction X, the pre-rotation speed direction generated by the pre-rotation air flow is the impeller rotation direction Y. In the state 1 (high rotation speed), the relative speed (positively correlated with the attack angle of the air flow) is w1, the attack angle of the inlet air flow is in a design state, the connection speed (positively correlated with the rotation speed of the impeller) is u1, the axial speed of the main air flow of the inlet air is C1 x, and the pre-rotation direction speed generated by the pre-rotation air flow is C1 y. When the rotation speed is reduced to the state 2, the traction speed u1 (positively correlated with the rotation speed of the impeller) is reduced to the traction speed u2, and at the moment, the speed of the main air flow is reduced to C2x, so that the air flow attack angle in the state 2 is kept unchanged (still in a design state), the pre-rotation direction speed generated after the pre-rotation air flow and the main air flow are converged at the moment is enabled to be C2y through a pre-design, at the moment, the absolute air flow speed is C2, the relative traction speed u2 is achieved, and at the moment, the relative speed (positively correlated with the air flow attack angle) is w2, and the direction of the relative speed w1 is the same, so that the air inlet air flow attack angle is kept unchanged. In the illustrated embodiment, C2y and C1y are substantially identical. In some embodiments, if the inlet main air flow axial velocity C2x drops too fast, then the compensating effect of the pre-swirl flow will be greater, and C2y will be greater than C1y; if the axial velocity of the main intake air flow C2x decreases slowly, the compensation effect of the pre-swirl flow is reduced, and C2y is smaller than C1 y. For an engine with a fixed design state, the change rule of the air inlet speed of the engine and the rotating speed of the air compressor is relatively fixed, so that the change rule of the proper air inlet pre-rotation supplementing effect can be realized by introducing a proper air flow regulating device 6, and the air inlet attack angle is maintained to be close to the design state.

In general, through the design of the air flow regulating device 6 and the prerotation air flow generator 5, the air inlet prerotation automatic regulation of the aero-engine in the working process can be realized, so that the aero-engine has better anti-surge effect, compressor efficiency and engine overall performance under most engine working speeds.

Specifically, the aviation scroll engine shown in fig. 1 is illustrated:

When the engine works at the design rotation speed N1, the inlet attack angle in front of the first-stage axial flow compressor 2 is in a design state; when the working rotation speed is reduced to N2 (generally about 90 percent N1), the positive attack angle of the air inlet is slowly increased, and the circulation capacity of the centrifugal compressor 1 relative to the axial flow compressor 2 is continuously reduced; when the working rotation speed is reduced to N2, in order to prevent surging, the air release valve 3 and the anti-asthma air release valve 4 are opened to realize air inflow pre-rotation and anti-asthma air release, and the relative circulation capacity of the centrifugal compressor 1 is increased due to the air inflow pre-rotation and the anti-asthma air release, and meanwhile, the air inflow attack angle in front of the first-stage axial flow compressor 2 is restored to be close to the design state; when the working rotation speed continues to drop to N3, the drop amplitude of the air inlet air flow speed is far greater than the drop amplitude of the rotation speed, and the deviation of the air inlet attack angle is compensated because the flow and the speed drop amplitude of the pre-rotation air flow (namely the product of the flow and the speed drop amplitude is a momentum value and is positively related to the pre-rotation effect) are relatively small, so that the deviation is maintained near the design state. In some embodiments, for aviation turboshaft engines with well-matched designs and moderate performance requirements such as fuel consumption, the air flow regulating device 6 can be omitted, so that reliability can be improved theoretically and cost can be reduced.

In addition, under most working conditions where the pre-swirl flow acts in the example, the pressure and density of the pre-swirl flow are higher than those of the main inlet flow due to the higher P2.5 bleed air pressure, so that the density of the inlet air flow can be improved, and the power of the aeroengine can be improved.

According to the aeroengine anti-surge system provided by the embodiment, the adjustable pre-rotation air flow is introduced into the air inlet air flow to change the pre-rotation amount of the inlet of the air compressor, so that the attack angle of the air flow at the inlet of the first-stage rotor blade is restored to be a value close to the design state, the air flow separation on the blade back is eliminated, and the surge phenomenon is avoided. Compared with the scheme of direct deflation of the deflation mechanism, the anti-asthma system of the aero-engine can reduce the flow requirement of anti-asthma deflation and improve the efficiency of the air compressor and the performance of the engine.

As an alternative embodiment, as shown in fig. 3, the air release valve 3 is directly communicated with the main air flow between the centrifugal compressor 1 and the axial flow compressor 2, the air release valve 3 is an opening-adjustable electric control valve, and the flow of the anti-asthma air release can be controlled by adjusting the opening of the electric control valve. The air flow regulating device 6 is also directly communicated with the main air flow between the centrifugal compressor 1 and the axial flow compressor 2, and the main air flow between the centrifugal compressor 1 and the axial flow compressor 2 is used for supplying air to the inside of the air flow regulating device 6.

Example 2

The embodiment provides an aero-engine anti-surge method, which is used for the aero-engine anti-surge system and comprises the following steps: when the rotation speed of the aero-engine is reduced, the pre-swirl flow generator 5 is used for feeding the pre-swirl flow to the air inlet of the air compressor, so that the inlet attack angle is maintained to be in accordance with the design state.

Referring to fig. 2 for specific analysis, taking fig. 2 as an example, when the air flow is in a high rotation speed state, the relative speed is w1, the attack angle of the inlet air flow is in a design state, and the connection speed is u1; at this time, the axial speed of the main air flow is C1 x, the pre-spinning direction speed generated by the pre-spinning air flow is C1y, when the rotating speed is reduced to a small rotating speed state, the dragging speed u1 is reduced to the dragging speed u2, the main air flow speed is reduced to C2x, the pre-spinning direction speed generated after the pre-spinning air flow and the main air flow are converged is C2y, and the relative speed at this time is w2; w1 and w2 are positively correlated with the angle of attack of the air flow, and u1 and u2 are positively correlated with the impeller speed.

Specifically, the main air flow speed is set to be gradually reduced to be A, and C1y is approximately equal to C2y; when the main air flow speed is lower than A, C1y < C2y; when the main air flow rate decreases at a rate less than A, C1y > C2y.

According to the aeroengine anti-surge method, the adjustable pre-rotation air flow is introduced into the inlet air flow to change the pre-rotation amount of the inlet of the air compressor, so that the attack angle of the inlet air flow of the first-stage rotor blade is restored to a value close to the design state, the air flow separation on the blade back is eliminated, and the surge phenomenon is avoided. Compared with the scheme of direct deflation of the deflation mechanism, the anti-asthma system of the aero-engine can reduce the flow requirement of anti-asthma deflation and improve the efficiency of the air compressor and the performance of the engine.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.

Claims

1. An aero-engine anti-surge system comprising:

A compressor adapted to receive a flow of gas therein;

A bleed valve (3), one port of which is communicated with the air flow in the compressor;

an anti-asthma air release valve (4) communicated with the air release valve (3) for anti-asthma air release;

characterized by further comprising:

And the pre-swirl airflow generator (5) is communicated with the inside of the air release valve (3) or the air compressor and is configured to send pre-swirl airflow to the air inlet of the air compressor after air is introduced into the air release valve (3) or the air flow in the air compressor so as to change the pre-swirl of main airflow at the inlet of the air compressor.

2. The aircraft engine anti-surge system of claim 1 wherein the degree of pre-swirl flow to main flow compensation is proportional to the degree of decrease in main flow velocity.

3. The aircraft engine anti-surge system of claim 2, wherein:

4. An aero-engine anti-surge system according to any of claims 1-3, further comprising an air flow regulating device (6) connected between said bleed valve (3) and said pre-swirl flow generator (5) to regulate the degree of pre-swirl flow compensation for the main air flow.

5. Aeroengine anti-surge system according to any of claims 1-4, wherein said compressor comprises a centrifugal compressor (1) and an axial compressor (2), said axial compressor (2) being provided at the intake end, and said bleed valve (3) being in communication between said centrifugal compressor (1) and said axial compressor (2).

6. An aero-engine anti-surge method for an aero-engine anti-surge system according to any of claims 1-5, characterized in that the pre-swirl flow is fed to the compressor inlet by means of a pre-swirl flow generator (5) when the speed of the aero-engine decreases, so that the inlet angle of attack is maintained in accordance with the design.

7. The aircraft engine anti-surge method of claim 6 wherein;

8. The aircraft engine anti-surge method of claim 7, wherein:

when the main air flow speed is lower than A, C1y is less than C2y;

when the main air flow speed is lower than A, C1y > C2y.

9. The aircraft engine anti-surge method of claim 8 wherein w1 and w2 are positively correlated with airflow angle of attack and u1 and u2 are positively correlated with impeller speed.