Turbofan engine fan booster stage test method

Abstract

The invention discloses a turbofan engine fan booster stage test method. The test method comprises the following steps: obtaining a turbofan engine fan booster stage working line; determining a safety line according to the working line; carrying out a mechanical operation test on the fan booster stage of the turbofan engine, and enabling the fan booster stage to work on the safety line at the same time; and after the mechanical operation test is completed, carrying out a characteristic recording test and a surge test of the fan booster stage according to the safety line. By giving safe operation lines of the inner culvert and the outer culvert of the performance test piece, the test piece is ensured not to have unexpected surge, flutter and other instability phenomena during mechanical operation and characteristic recording test, the test risk is reduced, and the test data validity is improved. And after being verified by a mechanical operation test, the safety line is applied to a subsequent characteristic recording test and a surge test, so that the reliability and the safety of the subsequent test are ensured.

Description

Technical Field

[0001] The invention relates to the field of aviation turbofan engine testing, and in particular to a turbofan engine fan boost stage testing method. Background Art

[0002] The fan boost stage is the low-pressure compression component at the front of the turbofan engine. After the airflow passes through the fan, it is divided into two streams, entering the outer duct and inner duct respectively. After completing the component design, the fan duct, fan inner duct + boost stage performance parameters, and surge margin of each speed performance assessment point can be obtained through the fan boost stage performance test to verify whether the design results meet the overall design requirements. In order to reduce the power of the test piece, the fan boost stage of the entire machine is usually scaled down to carry out the scaled fan boost stage performance test.

[0003] The fan boost stage performance test usually includes mechanical operation test, characteristic acquisition test and surge test. The mechanical operation test is to run the test piece from 0 to the maximum speed to verify that the structural strength meets the speed requirements of the performance test; the characteristic acquisition test usually includes the characteristic acquisition of the test piece at each speed from the blocking point to the working line, and a certain margin is acquired to verify the performance requirements of the performance assessment point; the surge test usually includes the characteristic acquisition of the test piece at each speed from the working line to the stall / surge state, and the surge margin requirements.

[0004] The fan boost stage of a turbofan engine has two ducts, the inner duct and the outer duct. When conducting the fan boost stage performance test, the operating point characteristics of the inner and outer ducts at each speed are adjusted respectively by controlling the valve opening at the inner and outer duct outlets.

[0005] In the prior art, when recording the fan boost level 0 to takeoff speed internal characteristics, first adjust the outer culvert outlet valve, adjust the outer culvert to the ground working line, fix the valve opening, and then adjust the internal culvert outlet valve to record the characteristics; when recording the takeoff to maximum speed internal characteristics, the outer culvert is fixed at the air working line. When recording the external culvert characteristics, the same method is used, 0 to takeoff speed fixed internal at the ground working line, takeoff to maximum speed fixed internal at the air working line.

[0006] Since the instability of the test piece may cause non-design conditions such as scraping between the test piece blades and the casing, scraping between the grate teeth and the stator blade ring, etc., the performance of the test piece will be reduced, affecting the verification results of the performance assessment points of the characteristic admission test. Therefore, before completing the characteristic admission test, it is not desirable for the test piece to experience instability such as surge and flutter. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defect of accidental instability that is prone to occur when conducting mechanical operation tests and characteristic acquisition tests in the prior art, and to provide a method for testing the fan boost stage of a turbofan engine.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] A turbofan engine fan boost stage test method, the test method comprising:

[0010] Obtain working lines for the fan boost stage of a turbofan engine;

[0011] According to the working line, a safety line is determined;

[0012] Conducting a mechanical operation test of the fan boost stage of a turbofan engine while making the fan boost stage operate at the safety line;

[0013] After the mechanical operation test is completed, the fan boost level characteristic admission test and the inlet and outlet test are carried out according to the safety line.

[0014] In this scheme, by giving the inner and outer safe operation lines of the fan boost stage performance test piece, it is ensured that the test piece does not experience unexpected surge, flutter and other instability phenomena during mechanical operation and characteristic acquisition tests, and the mechanical operation working line of the fan boost stage performance test piece can be obtained, reducing the risk of fan blockage state flutter caused by the full opening of the outlet valve during the mechanical operation test of the traditional test method, and facilitating the comparison of mechanical operation test data on different test days and even different test benches, thereby improving the validity of the test data. After the safety line is verified by the mechanical operation test, it is applied to the subsequent characteristic acquisition test and inlet surge test to ensure the reliability and safety of the subsequent tests.

[0015] Preferably, the working line includes an intrinsic working line and an extrinsic working line.

[0016] Preferably, the security line includes an intrinsic security line and an extrinsic security line, and the determining of the security line according to the working line includes:

[0017] The intrinsic safety line is determined according to the intrinsic working line, and the extrinsic safety line is determined according to the extrinsic working line.

[0018] In this scheme, the characteristics of the external operating point of the fan boost stage of the turbofan engine have a certain influence on the characteristics of the internal operating point and the surge margin, and this influence increases with the increase of the bypass ratio. This scheme ensures the safety of the test process and the reliability of the test results by simultaneously controlling the internal safety line and the external safety line.

[0019] Preferably, after the mechanical operation test is completed, a characteristic admission test of the fan boost level and a breathing test are performed according to the safety line, including:

[0020] Adjust the opening of the inner and outer outlet valves to make the inner and outer valves work on the safety line, increase the speed to the target speed of characteristic recording, and adjust the working point back to the safety line;

[0021] Carry out admission based on both internal and external characteristics.

[0022] Preferably, the step of carrying out the admission of connotation characteristics and extrinsic characteristics includes:

[0023] S100: Fix the culvert on the ground working line and record the internal characteristics of the test piece at the speed from slow to take-off;

[0024] S200: Fix the culvert on the aerial working line and record the culvert characteristics of the test piece from takeoff to the highest speed;

[0025] S300: fix the connotation at the safety line and record the external characteristics of the test piece at the speed from slow speed to 0.8 speed;

[0026] S400: Fix the inner content at the ground working line and record the outer content characteristics of the test piece at a speed from 0.8 to take-off speed;

[0027] S500: Fix the inner part on the aerial working line and record the outer part characteristics of the test piece from take-off speed to maximum speed;

[0028] S600: Adjust the inner and outer culvert working points back to the safety line;

[0029] S700: Switch to the next target speed, and repeat S100 to S600.

[0030] Preferably, the mechanical operation test of the fan boost stage of the turbofan engine is performed while making the turbofan engine operate on the safety line, including:

[0031] S10: The inner outlet valve and the outer outlet valve are fully opened, and the speed is increased to the slow speed;

[0032] S20: Adjust the opening of the inner and outer outlet valves to make the inner and outer outlet valves work at a safe level;

[0033] S30: Increase the speed to the next one. After stabilization, if the inner and outer working points deviate from the safety line, adjust the outlet valve to make the working point return to the safety line.

[0034] S40: Repeat S30, control the speed to increase the step, ensure that the internal and external converted flow rate deviates from the safety line by less than 2%, until the maximum speed is reached, and complete the mechanical operation test.

[0035] In this scheme, after completing the current speed test subject, the inner and outer operating points of the fan boost stage return to the safety line and then increase / decrease to the next speed to enhance test safety.

[0036] Preferably, determining the safety line according to the working line includes:

[0037] Determine the inherent safety line from slow to take-off speed: the converted flow rate at each speed of the inherent safety line increases by 40% to 0% compared with the inherent ground working line;

[0038] Determine the implicit safety line from takeoff to maximum speed: the implicit safety line coincides with the implicit ground working line, and the implicit safety line increases the converted flow rate at each speed by 5% to 1% compared with the implicit aerial working line;

[0039] Determine the outer culvert safety line: the safety line converted flow is between the outer culvert ground working line and the outer culvert aerial working line.

[0040] Preferably, from slow speed to maximum speed, the safety line converted flow rate increases by 30% to 1% compared with the outer culvert ground working line, and decreases by 50% to 0% compared with the outer culvert aerial working line.

[0041] Preferably, the determination of the slow-to-takeoff speed connotation safety line: the conversion flow of each speed of the connotation safety line is increased by 40% to 0% compared with the connotation ground working line, including:

[0042] The higher the rotation speed of the test piece, the closer the internal safety line is to the internal ground working line.

[0043] Preferably, the step of determining the outer culvert safety line: the safety line conversion flow is between the outer culvert ground working line and the outer culvert aerial working line comprises:

[0044] The higher the rotation speed of the test piece is, the closer the outer culvert safety line is to the outer culvert aerial working line.

[0045] The positive and progressive effects of the present invention are: the test method of the present invention, by providing the internal and external safety operation lines of the given performance test piece, ensures that the test piece does not experience unexpected surge, flutter and other instability phenomena during mechanical operation and characteristic acquisition tests, and can obtain the mechanical operation working line of the fan boost stage performance test piece, reducing the risk of fan blockage state flutter caused by the full opening of the outlet valve during the mechanical operation test, while facilitating the comparison of mechanical operation test data tested on different test days or even on different test benches, and improving the validity of the test data. After the safety line is verified by the mechanical operation test, it is applied to the subsequent characteristic acquisition test and inlet surge test to ensure the reliability and safety of the subsequent tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the internal structure of a turbofan engine fan boost stage performance test piece used in one embodiment of the present invention.

[0047] Figure 2 It is a schematic diagram of the flow-pressure ratio characteristic line of the fan boost stage.

[0048] Figure 3It is a schematic diagram of the fan boost stage external flow-pressure ratio characteristic line.

[0049] Figure 4 It is a schematic diagram of the flow-pressure ratio characteristic line and safety line of the fan boost stage.

[0050] Figure 5 It is a schematic diagram of the fan boost stage external flow-pressure ratio characteristic line and safety line.

[0051] Figure 6 The present invention is a flowchart of a method for testing a fan boost stage of a turbofan engine according to an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0053] This embodiment provides a turbofan engine fan boost stage test method, which ensures that the test piece does not experience unexpected surge, flutter and other instability phenomena during mechanical operation and characteristic recording tests by giving a safety line for the performance test piece. Figure 1 As shown, the test piece includes a test piece inlet 1, an inner duct outlet 2, an outer duct outlet 3, an inner duct outlet control valve 4, and an outer duct outlet control valve 5.

[0054] Specifically, see Figure 6 As shown, the turbofan engine fan boost stage test method includes the following steps:

[0055] Obtain working lines for the fan boost stage of a turbofan engine;

[0056] Determine the safety line based on the work line;

[0057] Conduct mechanical operation test of the turbofan engine fan boost stage and make the turbofan engine operate at the safety line;

[0058] After the mechanical operation test is completed, the fan boost stage characteristic admission test and the surge test are carried out according to the safety line.

[0059] By giving the performance test piece internal and external safety operation lines, it is ensured that the test piece does not experience unexpected surge, flutter and other instability phenomena during mechanical operation and characteristic acquisition tests, and the mechanical operation working line of the fan boost stage performance test piece can be obtained to reduce the risk of fan blockage state flutter caused by full opening of the outlet valve during the mechanical operation test. At the same time, it is convenient to compare the mechanical operation test data of different test days and even different test benches, and improve the validity of the test data. After the safety line is verified by the mechanical operation test, it is applied to the subsequent characteristic acquisition test and inlet surge test to ensure the reliability and safety of the subsequent tests.

[0060] Figure 2 and Figure 3 They are schematic diagrams of the inner and outer culvert flow-pressure ratio characteristic lines, wherein the horizontal axis is the converted flow, the vertical axis is the total pressure ratio, and the working line includes the inner working line and the outer culvert working line, specifically, the inner ground working line 6, the inner air working line 7, the outer ground working line 8, and the outer air working line 9. The inner and outer culvert converted flow rates of the test piece are obtained by converting the physical flow rate to the standard atmospheric state, the inner total pressure ratio is obtained by the total pressure of the inner outlet 3 of the test piece / the total pressure of the inlet 1 of the test piece, and the outer culvert total pressure ratio is obtained by the total pressure of the outer culvert outlet 2 of the test piece / the total pressure of the inlet 1 of the test piece.

[0061] Experimental studies have shown that the characteristics of the outer working point of the fan boost stage of a turbofan engine have a certain influence on the characteristics of the inner working point and the surge margin, and this influence increases with the increase of the bypass ratio. At the same speed, when the outer working point is at a small flow rate and high pressure ratio, the bypass ratio decreases, the inner design working point flow rate and pressure ratio increase, and the surge margin increases; conversely, when the outer working point is at a large flow rate and low pressure ratio, the bypass ratio increases, the inner design working point flow rate and pressure ratio decrease, and the surge margin decreases. On the other hand, the characteristics of the inner working point of the fan boost stage have little effect on the performance and surge margin of the outer working point.

[0062] Usually, when the turbofan engine fan boost stage works at low speed, the surge margin of the internal working line is small, and the whole machine adopts the boost stage outlet bleed to meet the surge margin requirements. However, the performance test piece has no bleed mechanism at the boost stage outlet. When recording the low-speed external bypass characteristics of the test piece, if the usual practice of "fixing the internal working point on the working line and recording the external bypass characteristics" is followed, when the external bypass works at the maximum flow state (blocking point), the bypass ratio is very large, and the surge margin of the internal bypass may be less than 0. It is very easy for the internal bypass surge / stall to occur on the working line, causing the performance of the test piece to decline, affecting the verification results of the performance assessment points of the characteristic recording test.

[0063] On the other hand, when doing mechanical operation tests, if the inner and outer duct valves of the fan boost stage are fully open and the fan duct operates in a blocked state, according to the classic flutter theory, blockage flutter may occur at medium and low speeds, and supersonic flutter may occur at high speeds, posing risks to subsequent characteristic acquisition tests.

[0064] In this embodiment, determining the safety line includes the following:

[0065] Determine the internal safety line from slow to take-off speed: the converted flow rate at each speed of the internal safety line is increased by 40% to 0% compared with the internal ground working line, and the total pressure ratio is obtained by interpolation of the internal characteristic line according to the converted flow rate;

[0066] Determine the implicit safety line from takeoff to maximum speed: the implicit safety line coincides with the implicit ground working line, and the implicit safety line increases the converted flow rate at each speed by 5% to 1% compared with the implicit aerial working line;

[0067] Determine the outer culvert safety line: the converted flow of the outer culvert safety line is between the outer culvert ground working line and the outer culvert aerial working line.

[0068] The relationship between the connotation safety line 10 and the connotation working line can be referred to Figure 4 As shown, the relationship between the outer safety line 11 and the outer working line can be referred to Figure 5 shown.

[0069] From slow speed to maximum speed, the safety line conversion flow rate increases by 30% to 1% compared with the outer culvert ground working line, and decreases by 50% to 0% compared with the outer culvert aerial working line. The higher the speed of the test piece, the closer the inner safety line is to the inner ground working line. In addition, the higher the speed of the test piece, the closer the outer culvert safety line is to the outer culvert aerial working line.

[0070] In this embodiment, according to the test sequence, the safety line is first the mechanical operation line, and then used in the characteristic recording test and the inlet surge test. During the mechanical operation test, by controlling the outlet valve opening, the inner and outer culverts of the test piece at each speed work on the safety line to avoid the working state where the fan may flutter; when recording the low-speed outer culvert characteristics of the test piece, the inner culvert is adjusted to be fixed on the safety line to avoid surge / stall caused by the change of the outer culvert working point, thereby avoiding performance degradation.

[0071] Accordingly, when determining the safety line, the intrinsic safety line is determined according to the intrinsic working line, and the extrinsic safety line is determined according to the extrinsic working line.

[0072] The characteristics of the external operating point of the fan boost stage of a turbofan engine have a certain influence on the characteristics of the internal operating point and the surge margin, and this influence increases with the increase of the bypass ratio. This scheme ensures the safety of the test process and the reliability of the test results by simultaneously controlling the internal safety line and the external safety line.

[0073] The mechanical running test of the turbofan engine fan boost stage includes the following steps:

[0074] S10: The inner outlet valve and the outer outlet valve are fully opened, and the speed is increased to the slow speed;

[0075] S20: Adjust the opening of the inner and outer outlet valves to make the inner and outer outlet valves work at a safe level;

[0076] S30: Increase the speed to the next one. After stabilization, if the inner and outer working points deviate from the safety line, adjust the outlet valve to make the working point return to the safety line.

[0077] S40: Repeat S30, control the speed to increase the step, ensure that the internal and external converted flow rate deviates from the safety line by less than 2%, until the maximum speed is reached, and complete the mechanical operation test.

[0078] After completing the current speed test subject, the inner and outer operating points of the fan boost stage return to the safety line and then increase / decrease to the next speed to enhance test safety.

[0079] In this embodiment, the characteristic admission test includes the following steps:

[0080] Adjust the opening of the inner and outer outlet valves to make the inner and outer valves work on the safety line, increase the speed to the target speed of characteristic recording, and adjust the working point back to the safety line;

[0081] Carry out admission based on both internal and external characteristics.

[0082] In this embodiment, the above-mentioned carrying out of the internal characteristic and the external characteristic admission specifically includes the following steps:

[0083] S100: Fix the culvert on the ground working line and record the internal characteristics of the test piece at the speed from slow to take-off;

[0084] S200: Fix the culvert on the aerial working line and record the culvert characteristics of the test piece from takeoff to the highest speed;

[0085] S300: fix the connotation at the safety line and record the external characteristics of the test piece at low speed (slow speed to 0.8 speed);

[0086] S400: Fix the inner content at the ground working line and record the outer content characteristics of the test piece at medium and high speeds (0.8 rpm to take-off speed);

[0087] S500: Fix the inner part on the aerial working line and record the outer part characteristics of the test piece from take-off speed to maximum speed;

[0088] S600: Adjust the inner and outer culvert working points back to the safety line;

[0089] S700: Switch to the next target speed, and repeat S100 to S600.

[0090] After the safety line is set, the fan boost stage surge test is implemented in the same way as the characteristic admission test. Note that after each surge and exit, first adjust the inner and outer operating points back to the safety line, and then switch to the next target speed.

[0091] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A turbofan engine fan boost level test method, characterized in that: The test method includes: Obtain working lines for the fan boost stage of a turbofan engine; According to the working line, a safety line is determined; Conducting a mechanical operation test of the fan boost stage of a turbofan engine while making the fan boost stage operate at the safety line; After the mechanical operation test is completed, the fan boost level characteristic admission test and the inlet and outlet test are carried out according to the safety line.

2. The turbofan engine fan boost level test method according to claim 1, characterized in that: The working line includes an inner working line and an outer working line.

3. The turbofan engine fan boost level test method according to claim 1, characterized in that: The safety line includes an intrinsic safety line and an extrinsic safety line. Determining the safety line according to the working line includes: The intrinsic safety line is determined according to the intrinsic working line, and the extrinsic safety line is determined according to the extrinsic working line.

4. The turbofan engine fan boost level test method according to claim 1, characterized in that: After the mechanical operation test is completed, the fan boost level characteristic admission test and the inlet and outlet test are carried out according to the safety line, including: Adjust the opening of the inner and outer outlet valves to make the inner and outer valves work on the safety line, increase the speed to the target speed of characteristic recording, and adjust the working point back to the safety line; Carry out admission based on both internal and external characteristics.

5. The turbofan engine fan boost level test method according to claim 4, characterized in that: The said carrying out of internal and external characteristics admission includes: S100: Fix the culvert on the ground working line and record the internal characteristics of the test piece at the speed from slow to take-off; S200: Fix the culvert on the aerial working line and record the culvert characteristics of the test piece from takeoff to the highest speed; S300: fix the connotation at the safety line and record the external characteristics of the test piece at the speed from slow speed to 0.8 speed; S400: Fix the inner content at the ground working line and record the outer content characteristics of the test piece at a speed from 0.8 to take-off speed; S500: Fix the inner part on the aerial working line and record the outer part characteristics of the test piece from take-off speed to maximum speed; S600: Adjust the inner and outer culvert working points back to the safety line; S700: Switch to the next target speed, and repeat S100 to S600.

6. The turbofan engine fan boost level test method according to claim 1, characterized in that: The mechanical operation test of the fan boost stage of the turbofan engine is performed, and the fan boost stage is operated at the safety line, including: S10: The inner outlet valve and the outer outlet valve are fully opened, and the speed is increased to the slow speed; S20: Adjust the opening of the inner and outer outlet valves to make the inner and outer outlet valves work at a safe level; S30: Increase the speed to the next one. After stabilization, if the inner and outer working points deviate from the safety line, adjust the outlet valve to make the working point return to the safety line. S40: Repeat S30, control the speed to increase the step, ensure that the internal and external converted flow rate deviates from the safety line by less than 2%, until the maximum speed is reached, and complete the mechanical operation test.

7. The turbofan engine fan boost level test method according to claim 3, characterized in that: Determining the safety line according to the working line includes: Determine the inherent safety line from slow to take-off speed: the converted flow rate at each speed of the inherent safety line increases by 40% to 0% compared with the inherent ground working line; Determine the implicit safety line from takeoff to maximum speed: the implicit safety line coincides with the implicit ground working line, and the implicit safety line increases the converted flow rate at each speed by 5% to 1% compared with the implicit aerial working line; Determine the outer culvert safety line: the safety line converted flow is between the outer culvert ground working line and the outer culvert aerial working line.

8. The turbofan engine fan boost level test method according to claim 7, characterized in that: From slow speed to maximum speed, the converted flow rate of the culvert safety line increases by 30% to 1% compared with the culvert ground working line, and decreases by 50% to 0% compared with the culvert aerial working line.

9. The turbofan engine fan boost level test method according to claim 7, characterized in that: The determination of the inherent safety line from slow speed to takeoff speed: the inherent safety line has a conversion flow rate of 40% to 0% at each speed compared with the inherent ground working line, including: The higher the rotation speed of the test piece, the closer the internal safety line is to the internal ground working line.

10. The turbofan engine fan boost level test method according to claim 7, characterized in that: Determining the outer culvert safety line: the safety line conversion flow is between the outer culvert ground working line and the outer culvert aerial working line, including: The higher the rotation speed of the test piece, the closer the outer culvert safety line is to the outer culvert aerial working line.

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