Turbine for test, test device and method for determining pneumatic instability boundary

Abstract

The invention discloses a turbine for testing, an engine testing device and a method for determining a pneumatic instability boundary of a compression system, which can determine the pneumatic instability boundary of the compression system in a complete machine environment, do not cause extra burden to the turbine and compression system components, and do not need to modify a tester and surrounding equipment on a large scale. The turbine for testing is used for replacing an original turbine in a complete machine surge test of an engine, and the engine testing device is used for the complete machine surge test of the engine. Stator blades of the test turbine are arranged to be rotatable blades, so that the circulation sectional area of the test turbine is reduced by rotating the stator blades, and the compression system can enter a surge state.

Description

Technical Field

[0001] The present invention relates to, but is not limited to, the technical field of engines, and more specifically, to a test turbine, an engine test device, and a method for determining the aerodynamic instability boundary of a compression system. Background Art

[0002] Compression systems are widely used in the power and energy industries. With the advancement of technology and the increase in application requirements, compression systems need to work under higher loads to achieve higher performance. High-load compression systems face more serious stability issues. The performance of a compression system is usually represented by a characteristic curve. The left boundary of the characteristic curve is the instability boundary of the compression system. When the working state of the compression system exceeds its instability boundary, flow instability phenomena such as surge will occur. When surge occurs, the airflow in the compression system oscillates greatly, eventually causing the compression system to degrade in performance and structural damage, and in severe cases, endangering the safety of the driven vehicle and generator set. Therefore, quickly and accurately evaluating the instability boundary of the compression system during the engine design stage plays a very important role in reducing development costs and improving performance and reliability.

[0003] At present, there are two methods to determine the aerodynamic instability boundary of the compression system: determination in the component environment and determination in the whole machine environment. However, there is a significant difference between the aerodynamic instability boundary of the compression system determined in the component environment and the aerodynamic instability boundary determined in the whole machine environment. The aerodynamic instability boundary obtained through experiments or simulations in the component environment often loses its accuracy in the whole machine environment. Therefore, in the process of engine development, a whole machine gasping test is usually carried out after the engine prototype is completed to determine the aerodynamic instability boundary of the engine's compression system in the whole machine environment.

[0004] In current engineering, the fuel step method or the high-pressure gas filling method is usually used to obtain the instability boundary of the compression system under the whole machine environment. Both methods have significant defects. Among them, the fuel step method requires a large amount of fuel to be sprayed into the combustion chamber to increase the temperature and pressure of the combustion chamber, thereby causing the compression system to become unstable. The substantial temperature increase in the combustion chamber will deteriorate the working environment of the turbine, which will bring the risk of engine structural damage. The high-pressure gas filling method requires a stable high-pressure gas source support. For advanced aircraft engines in the industry, very high pressure is often required, which means that the tester and surrounding equipment need to be modified to provide a gas source that meets the requirements. The modification and matching of the gas source requires a lot of resources and will increase the risk of test delays. Summary of the invention

[0005] The technical problem to be solved by the present application is to provide a test turbine, an engine test device and a method for determining the aerodynamic instability boundary of a compression system, which can determine the aerodynamic instability boundary of a compression system under a whole machine environment without causing additional burden on the turbine and compression system components, and without requiring large-scale modifications to the tester and surrounding equipment.

[0006] To this end, an embodiment of the present application provides a test turbine for replacing the original turbine in a whole-machine surge test of an engine. The stator blades of the test turbine are configured as rotatable blades so that the flow cross-sectional area of ​​the test turbine can be reduced by rotating the stator blades, thereby enabling the compression system of the engine to enter a surge state.

[0007] An embodiment of the present application also provides an engine test device for a whole-machine breathing test of an engine, the engine test device comprising: an original engine body and the test turbine; the engine body comprises a compression system, a combustion chamber and a tail nozzle, the compression system, the combustion chamber, the test turbine and the tail nozzle are connected in sequence.

[0008] The present application also provides a method for determining the aerodynamic instability boundary of a compression system in a whole machine environment, using the engine test device described in the above embodiment to perform a whole machine gasping test, the method comprising: Rotating the stator blades of the test turbine to a calibrated initial position; at the initial position, the stator blades of the test turbine are in the same position as the stator blades of the original turbine; Ignite and start the engine test device, and accelerate it to a set speed for the whole machine breathing test; controlling the stator blades of the test turbine to rotate gradually to reduce the flow cross-sectional area of ​​the test turbine until the compression system enters a surge state; An instability boundary point of the engine test device is determined, and the aerodynamic instability boundary of the compression system at a current rotation speed is determined according to the instability boundary point.

[0009] Compared with the prior art, this application has the following beneficial effects: Compared with the traditional method of using the fuel step method or the high-pressure gas filling method to measure the aerodynamic instability boundary of the compression system in the whole machine environment, the present application adopts the continuous variable geometry turbine method to force the engine test device to breathe, which can achieve the quasi-steady-state process in the whole machine environment. It will not introduce additional transient boundaries in the system, and can largely eliminate the impact of the implementation of the breathing method itself on the measurement of the aerodynamic instability boundary in the whole machine environment, thereby reducing the interference that the breathing method itself may bring to the measurement results, and a more accurate aerodynamic instability boundary can be obtained.

[0010] Compared with the existing whole-machine test method of using fuel step mode to force the surging, this method will not cause additional burden on the turbine and compression system components, which is beneficial to greatly enhance the safety of the whole-machine surging test and reduce the cost of the whole-machine surging test.

[0011] Compared with the existing whole machine test method of using high-pressure gas to force breathing, this method does not require large-scale modifications to the tester and surrounding equipment, which is conducive to shortening the test preparation cycle and reducing costs.

[0012] Compared with the existing method of using the whole machine simulation method to obtain the aerodynamic instability boundary in the whole engine environment, this method eliminates the influence of the error caused by the simulation modeling method on the prediction of the aerodynamic instability boundary of the compression system in the whole machine environment, and can more accurately obtain the aerodynamic instability boundary in the whole engine environment.

[0013] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to provide further understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0015] Figure 1 A schematic diagram of the aerodynamic structure of the main flow channel of an engine test device provided in some embodiments of the present application; Figure 2 A schematic diagram of the structure of an engine test device provided in some embodiments of the present application; Figure 3 A schematic cross-sectional view of an engine test device provided in some embodiments of the present application; Figure 4 A schematic diagram of a partial structure of an engine test device provided in some embodiments of the present application; Figure 5 for Figure 4 A schematic diagram of the structure from another perspective of the structure shown; Figure 6 A schematic diagram of the three-dimensional structure of an engine test device provided in some embodiments of the present application; Figure 7 A flowchart of a method for determining a pneumatic instability boundary of a compression system provided in some embodiments of the present application; Figure 8 A flow chart of a method for determining a pneumatic instability boundary of a compression system provided by one embodiment of the present application; Fig. 9 A schematic diagram of flow rate changes during a surge process according to an embodiment of the present application; Fig.10 A schematic diagram of a slope change process of a flow rate change curve during a surge process in an embodiment; Fig.11 A schematic diagram of a surge dynamic process according to an embodiment of the present application.

[0016] In the accompanying drawings, the components represented by the reference numerals are listed as follows: 11 compressor, 12 combustion chamber, 13 test turbine, 131 stator blade, 1321 rotating shaft, 1322 actuating ring, 1323 connecting rod, 1324 multi-degree-of-freedom bearing, 1325 sliding protrusion, 1327 first transmission shaft, 1328 roller, 1329 second transmission shaft, 133 inner casing of turbine, 134 outer casing of turbine, 1350 driving assembly, 1351 power source, 1352 push rod, 1353 third transmission shaft, 1354 actuating hole, 14 tail nozzle, 15 outer casing, 151 arc-shaped slide groove, 16 engine main shaft, 17 air inlet. DETAILED DESCRIPTION

[0017] The principles and features of the present application are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present application and are not used to limit the scope of the present application.

[0018] The embodiment of the present application provides a test turbine, an engine test device, and a method and device for determining the aerodynamic instability boundary of a compression system under a whole machine environment. The engine test device is used for a whole machine gasping test of an engine to determine the aerodynamic instability boundary of a compression system under a whole machine environment. The test turbine 13 is used to replace the original turbine in the whole machine gasping test of an engine. Figures 1 to 5 As shown, the engine test device includes: the original engine body and the test turbine 13. In other words, the engine test device is a modified original engine for a wheezing test, and the modified part is the turbine. The test turbine 13 is used to replace the original turbine and is installed in the corresponding position of the engine body. The structure of the engine body is the original structure of the engine. The engine body includes a compression system. The compression system includes a compressor 11 and, if necessary, may also include a fan and an air inlet 17 on the upstream side of the compressor 11, as well as a matching piping system. Figure 1The schematic diagram of the aerodynamic structure of the main channel of the engine test device simplifies the compression system into the compressor 11, and does not illustrate the fan and the matching piping system. The engine body may also include components such as the combustion chamber 12 and the tail nozzle 14, which are original components of the engine without modification. The test turbine 13 is located between the combustion chamber 12 and the tail nozzle 14. Along the flow direction of the gas, the compression system, the combustion chamber 12, the test turbine 13, and the tail nozzle 14 are connected in sequence. An air inlet 17 is provided on the upstream side of the compressor 11.

[0019] The test turbine 13 is mounted to the engine body. The stator blades 131 of the test turbine 13 are configured as rotatable blades, so that the flow cross-sectional area of ​​the test turbine 13 (specifically, the flow cross-sectional area of ​​the air flow channel where the stator blades 131 are located) is reduced by rotating the stator blades 131, so that the compression system can enter a surge state.

[0020] Among them, the stator blades of the original turbine are fixedly installed, so the flow cross-sectional area of ​​the airflow channel where the stator blades of the original turbine are located remains unchanged. The engine test device provided in the embodiment of the present application converts the traditional fixed geometry turbine with fixedly installed stator blades 131 into a variable geometry turbine with rotatable stator blades 131 (that is, the geometry of the turbine is continuously variable). This is equivalent to constructing a valve with adjustable opening downstream of the compression system. By adjusting the working angle of the stator blades 131 (that is, rotating the stator blades 131), the flow cross-sectional area of ​​the test turbine 13 can be adjusted, so that the test turbine 13 has the function of adjusting the opening, and there is a corresponding relationship between the working angle of the stator blades 131 and the opening of the test turbine 13. By reducing the opening of the test turbine 13, the compression system can enter a surge state.

[0021] Therefore, the engine test device can be used to carry out whole machine surge test to determine the aerodynamic instability boundary (also called stability boundary or surge boundary) of the compression system under the whole machine environment. During the test, the engine test device is fixed on the test bench.

[0022] like Figure 7 As shown, the determination method includes the following steps: Step S202: rotating the stator blades of the test turbine to a calibrated initial position; at the initial position, the stator blades of the test turbine are in the same position as the stator blades of the original turbine; Step S204: igniting and starting the engine test device, and accelerating to a set speed for the whole machine breathing test; Step S206: controlling the stator blades of the test turbine to rotate gradually to reduce the flow cross-sectional area of ​​the test turbine until the compressor enters a surge state; Step S208: determining the instability boundary point of the engine test device, and determining the aerodynamic instability boundary of the compressor at the current speed according to the instability boundary point.

[0023] During the test, by rotating the stator blades 131 to reduce the flow cross-sectional area of ​​the test turbine 13, the operating flow of the compression system can be gradually reduced, causing the compression system to enter a surge state, thereby achieving a quasi-steady-state process of surging under the whole machine environment. In this way, the aerodynamic instability boundary of the compression system under the whole machine environment can be described in a standardized manner, and the actual impact of upstream and downstream components on the compression system during the actual operation of the engine can be fully considered.

[0024] Compared with the traditional method of using the fuel step method or the high-pressure gas filling method to measure the aerodynamic instability boundary of the compression system in the whole machine environment, the present application adopts the continuous variable geometry turbine method to force the engine test device to breathe, which can achieve the quasi-steady-state process in the whole machine environment. It will not introduce additional transient boundaries in the system, and can largely eliminate the impact of the implementation of the breathing method itself on the measurement of the aerodynamic instability boundary in the whole machine environment, thereby reducing the interference that the breathing method itself may bring to the measurement results, and a more accurate aerodynamic instability boundary can be obtained.

[0025] On this basis, combined with the aerodynamic instability boundaries of the whole machine environment measured by other gasp methods, the direction and magnitude of the influence of other gasp methods on the aerodynamic instability boundaries can be obtained to a certain extent, and the deviation range and direction of other different gasp methods can be given, which facilitates the comparison between the aerodynamic instability boundaries of the compression system of engines of different sizes and designs obtained under different gasp methods.

[0026] Compared with the existing whole-machine test method of using fuel step mode to force the surging, this method will not cause additional burden on the turbine and compression system components, which is beneficial to greatly enhance the safety of the whole-machine surging test and reduce the cost of the whole-machine surging test.

[0027] Compared with the existing whole machine test method of using high-pressure gas to force breathing, this method does not require large-scale modifications to the tester and surrounding equipment, which is conducive to shortening the test preparation cycle and reducing costs.

[0028] Compared with the existing method of using the whole machine simulation method to obtain the aerodynamic instability boundary in the whole engine environment, this method eliminates the influence of the error caused by the simulation modeling method on the prediction of the aerodynamic instability boundary of the compression system in the whole machine environment, and can more accurately obtain the aerodynamic instability boundary in the whole engine environment.

[0029] In some exemplary embodiments, the test turbine 13 further includes an actuating device. The actuating device is connected to the stator blades 131 of the test turbine 13 and is configured to drive the stator blades 131 to rotate. Figure 2 As shown, the actuating device includes: a plurality of rotating shafts 1321 and a driving mechanism.

[0030] There are multiple stator blades 131, and multiple rotating shafts 1321 are arranged one by one corresponding to the multiple stator blades 131 of the test turbine 13. Each rotating shaft 1321 extends along the radial direction of the test turbine 13, and is connected to the corresponding stator blade 131, and is configured to drive the corresponding stator blade 131 to rotate around the corresponding rotating shaft 1321. The driving mechanism is connected to the multiple rotating shafts 1321, and is configured to drive the multiple rotating shafts 1321 to rotate synchronously, so as to synchronously adjust the working angles of the multiple stator blades 131.

[0031] Thus, during the test, the plurality of stator blades 131 of the test turbine 13 can be synchronously rotated by controlling the actuating device. The actuating device can be a device capable of achieving precise control, which is beneficial for precise control of the stator blades 131 during the test.

[0032] In some exemplary embodiments, the central axis of any rotating shaft 1321 passes through the centroid of the maximum stress cross section of the corresponding stator blade 131 .

[0033] The maximum stress section of the stator blade 131 refers to the section where the maximum stress of the stator blade 131 occurs, and this section is the key section of the stator blade 131. When the central axis of the rotating shaft 1321 passes through the centroid of this section, it is beneficial to improve the structural stability and reliability of the stator blade 131 during the test process, so as to reduce the risk of deformation, fracture, etc. of the stator blade 131 and the rotating shaft 1321.

[0034] In some exemplary embodiments, an air flow channel is provided in the test turbine 13, and a plurality of stator blades 131 are located in the air flow channel, which are configured to adjust the flow cross-sectional area of ​​the air flow channel by rotation, that is, to adjust the flow cross-sectional area of ​​the test turbine 13 (or to adjust the opening of the test turbine 13).

[0035] like Figure 4 and Figure 5 As shown, the two ends of any rotating shaft 1321 are rotatably connected to the radial inner wall surface and the radial outer wall surface of the airflow channel, thereby realizing two-point support of the stator blade 131, so as to improve the stability and reliability of the rotating shaft 1321 and the stator blade 131 during the test. The driving mechanism is located outside the airflow channel, and multiple rotating shafts 1321 penetrate the radial outer wall surface of the airflow channel and are connected to the driving mechanism.

[0036] The airflow channel can be enclosed by the inner casing 133 of the turbine and the outer casing 134 of the turbine, and the radial inner wall surface of the airflow channel is located at the inner casing 133 of the turbine, and the radial outer wall surface is located at the outer casing 134 of the turbine, and the inner casing 133 of the turbine is located radially outside the engine main shaft 16. A support structure such as a support groove or a support convex point can be provided on the radial inner wall surface of the airflow channel, and rotatably matched with the inner end of the rotating shaft 1321 to realize a rotatable connection.

[0037] In some exemplary embodiments, the radial inner wall surface and the radial outer wall surface where they connect to the rotating shaft 1321 are treated with high temperature resistant lubrication, which ensures the reliability and sealing of the rotating shaft 1321 while also ensuring that the rotating shaft 1321 is easy to rotate.

[0038] In some exemplary embodiments, Figure 2 , Figure 4 and Figure 5 As shown, the engine body includes a shell 15, the driving mechanism is located outside the shell 15, and a plurality of rotating shafts 1321 penetrate the radial outer wall surface of the air flow channel and the shell 15 and are connected to the driving mechanism.

[0039] This not only facilitates the installation of the driving mechanism, but also prevents the setting of the driving mechanism from affecting the internal flow channel structure of the engine test device, making it easier to simulate the instability process of the engine more realistically.

[0040] The outer casing 15 of the engine includes an outer casing of the engine, which is sleeved on the outer side of the outer casing 134 of the turbine. The outer end of the rotating shaft 1321 passes through the outer casing 134 of the turbine and the outer casing of the engine in sequence and extends out of the engine body.

[0041] In some exemplary embodiments, the driving mechanism includes: a plurality of adapter structures with multiple degrees of freedom, an actuating ring 1322 and a driving assembly 1350, such as Figures 2 to 5 shown.

[0042] The multiple transfer structures correspond to and are connected to the multiple rotating shafts 1321 one by one, and are configured to drive the multiple rotating shafts 1321 to rotate synchronously. The actuating ring 1322 is rotatably sleeved on the radial outer side of the housing 15, and is connected to the multiple transfer structures, and is configured to be able to rotate relative to the housing 15 around the central axis of the actuating ring 1322 to drive the multiple transfer structures to move, so that the multiple transfer structures respectively drive the corresponding rotating shafts 1321 to rotate. The driving assembly 1350 is connected to the actuating ring 1322, and is configured to drive the actuating ring 1322 to rotate.

[0043] Through the multiple degrees of freedom transition structure, the synchronous rotation of the plurality of stator blades 131 around the central axis of their respective corresponding rotating shafts 1321 can be achieved by utilizing the rotation of the actuating ring 1322 along the circumferential direction of the engine body.

[0044] The actuating ring 1322 can be matched with the housing 15 of the engine body by means of multi-point centering. Figure 3 As shown, one of the housing 15 of the engine body and the actuating ring 1322 is provided with a plurality of (for example, three, four or more) arc-shaped slide grooves 151 extending along the circumferential direction of the engine body, and the other is correspondingly provided with a plurality of sliding protrusions 1325, and the plurality of sliding protrusions 1325 are embedded one by one in the corresponding arc-shaped slide grooves 151, so that the actuating ring 1322 and the housing 15 of the engine body are coaxially sleeved together and can rotate relative to the housing 15, but the actuating ring 1322 is limited to axial movement relative to the housing 15. The driving assembly 1350 can be installed on the housing 15 of the engine body.

[0045] In some exemplary embodiments, Figure 4 and Figure 5 As shown, the transfer structure includes: a connecting rod 1323 connected to the rotating shaft 1321 and a multi-degree-of-freedom bearing 1324 connected to the connecting rod 1323. The multi-degree-of-freedom bearing 1324 is connected to the actuating ring 1322, and is configured to drive the connecting rod 1323 to move under the drive of the actuating ring 1322, so that the connecting rod 1323 drives the corresponding rotating shaft 1321 to rotate.

[0046] The connecting rod 1323 can be vertically connected to the rotating shaft 1321. The connecting rod 1323 can be provided with an axis hole, and the outer end of the rotating shaft 1321 can be inserted into the axis hole and rotate synchronously with the connecting rod 1323.

[0047] The multi-degree-of-freedom bearing 1324 may include at least one of a rod-shaped structure, a columnar structure, a spherical structure, etc., and the two connected parts may be able to achieve both relative rotation and relative sliding (i.e., the connection relationship between the two connected parts is a movable connection relationship with multiple degrees of freedom), so that the rotation of the actuating ring 1322 can be converted into the rotation of the connecting rod 1323, thereby driving the rotation of the rotating shaft 1321 and the stator blade 131. For example, Figure 4As shown, the multi-degree-of-freedom bearing 1324 includes: a first transmission shaft 1327 connected to the actuating ring 1322, a roller 1328 connected to the first transmission shaft 1327, a second transmission shaft 1329 connected to the roller 1328, and the second transmission shaft 1329 is connected to the connecting rod 1323. At least one of the connection relationship between the actuating ring 1322 and the first transmission shaft 1327, the connection relationship between the first transmission shaft 1327 and the roller 1328, the connection relationship between the roller 1328 and the second transmission shaft 1329, and the connection relationship between the second transmission shaft 1329 and the connecting rod 1323 is set to a movable connection relationship with multiple degrees of freedom (for example, relative rotation and relative sliding can occur), so that the rotation of the actuating ring 1322 can drive the connecting rod 1323 to rotate.

[0048] In some exemplary embodiments, the driving assembly 1350 may include a power source and a transmission mechanism. The transmission mechanism is connected to the actuating ring 1322 and is configured to drive the actuating ring 1322 to rotate. The power source may be, but is not limited to, a stepping motor, which facilitates precise control.

[0049] In one embodiment, Figure 6 As shown, one of the connecting rods 1323 is provided with an actuating hole 1354, and the transmission mechanism includes a push rod 1352. The push rod 1352 is inserted into the actuating hole 1354 and is in clearance fit with the actuating hole 1354, and is configured to be able to move linearly under the drive of the stepper motor and push the connecting rod 1323 to rotate, so that the connecting rod 1323 drives the actuating ring 1322 to rotate through the multi-degree-of-freedom bearing 1324.

[0050] Since the whole machine pressure test process does not require a large stroke of the actuating ring 1322 (the rotation amplitude is basically not greater than 10°), the push rod 1352, the actuating hole 1354 and the multi-degree-of-freedom bearing 1324 can be used to drive the actuating ring 1322. In this way, during the entire pressure test process, the movement direction of the push rod 1352 is single and the cooperation with the actuating hole 1354 is relatively reliable, and the situation where the push rod 1352 cannot be inserted into the actuating hole 1354 after being withdrawn will not occur.

[0051] Among them, the push rod 1352 and the actuating hole 1354 are clearance-matched to ensure that the push rod 1352 and the actuating hole 1354 can move relative to each other, so that the linear movement of the push rod 1352 can drive the connecting rod 1323 to rotate, and the connecting rod 1323 is connected to the actuating ring 1322 through the multi-degree-of-freedom bearing 1324, so it can drive the actuating ring 1322 to rotate.

[0052] like Figure 6As shown, the push rod 1352 is located on one side of the axial direction of the actuating ring 1322, and the movement direction of the push rod 1352 is perpendicular to the axis of the actuating ring 1322, so that the distance between the push rod 1352 and the actuating ring 1322 remains unchanged during the movement, which can prevent the push rod 1352 from interfering with the actuating ring 1322. The rotating shaft of the test turbine can be located on the other side of the axial direction of the actuating ring 1322, and the connecting rod 1323 matched with the push rod 1352 extends from one side of the axial direction of the actuating ring 1322 to the other side of the axial direction of the actuating ring 1322, so that it is convenient to reasonably utilize the space on both sides of the axial direction of the actuating ring 1322 to reasonably arrange the rotating shaft, the connecting rod 1323, the push rod 1352 and the stepping motor. The connecting rod 1323 can be located on the radial inner side of the actuating ring 1322, and the actuating hole 1354 can penetrate the connecting rod 1323 along the radial direction of the actuating ring 1322. The push rod 1352 may be provided with a third transmission shaft 1353 , and the third transmission shaft 1353 is clearance-matched with the actuating hole 1354 .

[0053] Of course, multiple connecting rods 1323 may also be provided with actuating holes 1354, and the push rod 1352 may be inserted into the actuating hole 1354 to drive the actuating ring 1322 to rotate a certain angle, then withdraw and enter the next actuating hole 1354. This solution is beneficial to increasing the rotation range of the actuating ring 1322.

[0054] In another embodiment, a plurality of jacks may be arranged at intervals along the circumferential direction on the actuating ring 1322. The transmission structure may include a push rod 1352 that can enter and exit the jack. The push rod 1352 may be arranged obliquely relative to the rotation axis of the actuating ring 1322 and may be inserted into the jack, and may slide against the hole wall of the jack to drive the actuating ring 1322 to rotate by a preset angle. Then, the force applied by the push rod 1352 to the actuating ring 1322 may be decomposed into an axial force and a circumferential force, so as to use the circumferential component force to drive the actuating ring 1322 to rotate. Therefore, when the power source 1351 drives the push rod 1352 to extend, the end of the push rod 1352 is inserted into the push hole of the actuating ring 1322, and drives the actuating ring 1322 to rotate. By reasonably setting the intervals between adjacent jacks, the actuating ring 1322 may be rotated by a preset angle each time the push rod 1352 is extended, so as to ensure that the stator blades rotate by a set angle (the set angle may be the same as or different from the preset angle). When the actuating ring 1322 rotates a preset angle, the power source 1351 drives the push rod 1352 to extend, and at this time, the adjacent jack just corresponds to the push rod 1352 .

[0055] In another embodiment, the transmission mechanism may also include a transmission gear, and the actuating ring 1322 is provided with an engaging portion. The transmission gear is engaged with the actuating ring 1322 and the rotation axes are parallel to each other, so as to drive the actuating ring 1322 to rotate.

[0056] In other embodiments, the transfer structure may also include a gear transmission structure. The actuating ring 1322 drives the rotating shaft 1321 to rotate through the gear transmission mechanism. For example, the gear transmission mechanism may include a first gear and a second gear, the first gear includes a first gear tooth and a second gear tooth coaxially arranged, and the first gear tooth is meshed with the actuating ring 1322. The second gear tooth and the second gear may be bevel gears. The second gear tooth is meshed with the second gear and the rotation axes are perpendicular to each other, and the second gear drives the rotating shaft 1321 to rotate coaxially.

[0057] Of course, the structural form of the transfer structure is not limited to the above-mentioned form, and may also be other structural forms, which are not listed here one by one.

[0058] In some exemplary embodiments, the engine test device further comprises: a detection device (not shown in the figure), configured to detect operating information of the engine test device. The operating information of the engine test device may include physical quantities used to characterize the performance of the compression system, and may also include operating information of other components of the engine test device.

[0059] For example, the detection device may include an outlet pressure probe for dynamically detecting the outlet cross-sectional pressure of the compressor 11. The number of outlet pressure probes may be multiple (e.g., not less than three), and the multiple outlet pressure probes are arranged at intervals along the circumference of the outlet of the compressor 11, so as to obtain the periodicity of the pressure signal along the circumferential rotation, and to determine the average pressure of the outlet cross-sectional pressure of the compressor 11 through the detection results of the multiple outlet pressure probes. The acquisition frequency of the outlet pressure probe is not less than 10kHz, so as to accurately capture the surge signal and the details of the change of static pressure in a typical surge cycle.

[0060] The detection device may also include an inlet pressure probe for dynamically detecting the pressure of the inlet section of the compressor 11. The number of the inlet pressure probes may be multiple, and the multiple inlet pressure probes are also arranged at intervals along the circumferential direction of the inlet of the compressor 11, so as to facilitate the determination of the average pressure of the inlet section of the compressor 11 through the data of the multiple inlet pressure probes. Thus, the dynamic changes of the inlet pressure of the compressor 11 and the dynamic changes of the outlet pressure can be mutually verified, so as to facilitate more accurate determination that the engine test device has indeed entered a surge state.

[0061] Generally speaking, when aerodynamic instability of the compressor 11 occurs, pressure fluctuations will be monitored at both the inlet and outlet sections of the compressor 11. By arranging pressure probes at both the inlet and outlet positions of the compressor 11, it is possible to mutually verify that aerodynamic instability has occurred when pressure signals of both sections fluctuate. If pressure fluctuations occur in only one of the sections, it is likely that the pressure fluctuation signal is caused by reasons other than aerodynamic instability of the compressor 11. Of course, the probability of this happening is low, so the design of arranging pressure probes at both the inlet and outlet is not a must.

[0062] The detection device may also include a sensor for directly or indirectly detecting the position of the stator blades 131 of the test turbine 13. Since there is a linkage relationship between the stator blades 131, the rotating shaft 1321, and the driving mechanism, the positions also have a corresponding relationship. Therefore, the sensor can directly detect the position of the stator blades 131, and can also detect the position of the corresponding components of the rotating shaft 1321 or the driving mechanism (such as the driving motor, the actuating ring 1322, the connecting rod 1323, etc.).

[0063] The detection device may also include a temperature sensor, a flow sensor, a speed sensor, etc., which are used to monitor various operating information of the engine test device during the test process.

[0064] In the above step S202, the calibrated initial position refers to the same position of the stator blades 131 of the test turbine 13 as the stator blades 131 of the original turbine, that is, at the initial position, the geometric shapes of the stator blades 131 of the test turbine 13, except for the position of the rotating shaft 1321, should be consistent with the geometric shapes of the stator blades 131 of the original turbine. The working angle of the stator blades 131 at the initial position can be recorded as 0°.

[0065] In the above step S204, the engine is accelerated to the speed required for the gasping test according to the normal experimental process. That is, after the engine test device is fixed on the test bench, the engine test device is ignited and pushed to the slow speed using the start control law of the engine before modification (i.e., the original engine), and then the engine test device is gradually accelerated using the acceleration control law of the engine before modification (i.e., the original engine). During the acceleration process, based on the detection that the exhaust temperature of the test turbine 13 exceeds the set temperature threshold, the engine test device is decelerated to the slow speed, and the stator blades 131 of the test turbine 13 are controlled to rotate to reduce the flow cross-sectional area of ​​the test turbine 13. This is because: after the turbine is modified into a variable geometry turbine, since the originally fixed stator blades 131 are changed to a rotatable design, gaps appear at the blade roots and blade tips, which leads to a decrease in turbine efficiency. The decrease in turbine efficiency will cause the exhaust temperature to overheat if the engine is started according to the original starting procedure. Reducing the flow cross-sectional area of ​​the variable geometry turbine will reduce the turbine exhaust temperature and thus alleviate the problem of exhaust temperature overheating.

[0066] Then continue to accelerate the engine test device until it reaches the minimum speed required for the gas test (the speed of the engine gas test can be one or more; when the speed of the gas test is multiple, the aerodynamic instability boundaries of the engine at different speeds are determined in order from low to high).

[0067] In the process of reducing the flow area of ​​the test turbine 13, the engine control system automatically adjusts the engine fuel injection amount to ensure that the rotation speed of the engine test device does not change.

[0068] In some exemplary embodiments, controlling the stator blades 131 of the test turbine 13 to rotate to reduce the flow cross-sectional area of ​​the test turbine 13 so that the compression system enters a surge state includes: Controlling the stator blades 131 to rotate to a set angle; Acquiring operation information of the engine test device, and judging whether the compression system enters a surge state according to the operation information of the engine test device; Based on the determination that the compression system enters a surge state, a step of determining an instability boundary point of the engine test device is performed; Based on the determination that the compression system has not entered the surge state, the process returns to the step of controlling the stator blades 131 to rotate at a set angle.

[0069] In this way, the stator blades 131 can be gradually rotated according to a given step size (i.e., a set angle), thereby gradually reducing the flow cross-sectional area of ​​the test turbine 13, achieving forced breathing in a quasi-steady state process, which is beneficial to improving the accuracy of the measured aerodynamic instability boundary of the compression system.

[0070] In some exemplary embodiments, the operation information of the engine test device includes: a physical quantity used to characterize the performance of the compression system, and a signal used to characterize the operating state of the engine test device.

[0071] The physical quantities used to characterize the performance of the compression system may include, but are not limited to, temperature (total temperature, static temperature), pressure (total pressure, static pressure), density, speed, flow, etc. The signals used to characterize the operating status of the engine test device may include, but are not limited to, acoustic signals, optical signals, etc.

[0072] Determine whether the compression system has entered a surge state based on the operating information of the engine test device, including: determining that the compression system enters a surge state based on that the operation information of the engine test device satisfies a determination condition for entering a surge state; Based on the fact that the operation information of the engine test device does not satisfy the determination condition for entering the surge state, it is determined that the compression system has not entered the surge state.

[0073] Among them, the judgment conditions for entering the surge state include at least one of the following: the physical quantity used to characterize the performance of the compression system meets the set surge condition, and the signal used to characterize the operating state of the engine test device has a set surge signal.

[0074] In some exemplary embodiments, the acquisition frequency of the physical quantity is not less than 10 kHz, so as to accurately capture the surge signal and the details of the change of the static pressure in a typical surge cycle.

[0075] In some exemplary embodiments, setting the gasping condition includes at least one of the following: the curvature change of the physical quantity satisfies a first set instability boundary condition, and the frequency of the periodic signal extracted according to the physical quantity satisfies a second set instability boundary condition.

[0076] The gasping signal is set to include at least one of a light signal and an acoustic signal. The acoustic signal may include but is not limited to: a low-frequency humming sound and / or a continuous blasting sound different from a normal operating state. The light signal may include but is not limited to: a flame leaping out of the outlet of the engine test device.

[0077] In some exemplary embodiments, data corresponding to a physical quantity (such as the outlet pressure of the compressor 11) is selected from the data corresponding to the physical quantity used to characterize the performance of the compression system, and a curve of the change of the physical quantity P over time is determined. Fig. 9 As shown in the figure, taking the flow rate as an example, the change process of the physical quantity during the surge process is shown, which is characterized by a periodic fluctuation process accompanied by alternating positive and negative fluctuations. The curvature calculation formula is used to calculate the curvature of the curve at each time t, as shown in Fig.10 shown.

[0078] For example, the average static pressure of the outlet section of the selected compressor 11 is P. The average static pressure P can be obtained by the following method: the dynamic pressure signals collected by multiple outlet pressure probes are averaged in the circumferential direction (i.e., summed and averaged), and filtered using a filter function (filtering out high-frequency and low-frequency signals). On this basis, a curve of the average static pressure P changing with time can be obtained, and then the curvature of the curve at each time t can be calculated using the curvature calculation formula.

[0079] The curvature calculation formula is: ; In the above formula, It represents the slope of the curve of the physical quantity P, that is, it represents the speed of the change of the physical quantity P; W represents the window length for calculating the slope, which is a positive integer; It represents the change of the physical quantity P within the time length W; f represents the sampling frequency.

[0080] The first set of instability boundary conditions includes: ; In the above formula, The slope of the physical quantity P at time N is A, and A represents the threshold value of the compressor 11 with different configurations. Represents the flow rate of compressor 11. The physical meaning of this formula is: when the speed of the change process of the physical quantity P reaches A, and the flow rate of compressor 11 is positive at this time, it is considered that the instability boundary is reached, and this operating condition is used as the instability boundary point of compressor 11. The size of the A value is related to the compressor 11 of different configurations (such as axial compressor, centrifugal compressor, axial-flow centrifugal combination compressor, etc.) carried by the calculated engine, and is also related to the size and power level of the engine. In practical applications, it is usually selected based on existing cases of engines with similar configurations, similar sizes and power levels.

[0081] In some exemplary embodiments, the frequency of the periodic signal extracted from the physical quantity is recorded as . The extraction method is as follows: using real-time fast Fourier transform, the main periodic signal frequencies in the selected physical quantity are extracted.

[0082] For example, the average static pressure of the outlet section of the selected compressor 11 is P. The average static pressure P can be obtained by the following method: the dynamic pressure signals collected by multiple outlet pressure probes are averaged circumferentially (i.e., summed and averaged), and filtered using a filter function (filtering out high-frequency and low-frequency signals). The main periodic signal frequency in the dynamic pressure signal is extracted using real-time fast Fourier transform, which is .

[0083] The second set of instability boundary conditions includes: ; In the above formula, is a constant ， It is usually selected based on the specific configuration, size and power level of the engine compressor 11. The Helmholtz frequency of the engine test device under the current state of the prediction calculation is as follows: When , it means that “the frequency of the periodic signal extracted according to the physical quantity satisfies the second set instability boundary condition” is established.

[0084] The calculation formula is: In the above formula, represents the speed of sound at the outlet of the compressor 11, is the equivalent cross-sectional area of ​​the outlet of compressor 11, is the equivalent volume of the combustion chamber 12, is the equivalent length of the combustion chamber 12.

[0085] In some exemplary embodiments, in the step of controlling the stator blades 131 to rotate to a set angle, the time required for the stator blades 131 to rotate to the set angle is not less than the set time, so that the stator blades 131 rotate smoothly.

[0086] In one example, the setting angle may be but not limited to 1°, and the setting duration may be but not limited to not less than 1s (such as 1s, 2s, 3s, etc.) to ensure the smoothness of the position adjustment of the stator blades 131, thereby improving the accuracy of the measured aerodynamic instability boundary.

[0087] In some exemplary embodiments, determining an instability boundary point of an engine test device, and determining an aerodynamic instability boundary of a compression system at a current rotation speed according to the instability boundary point, includes: The last working state of the engine test device before the compression system enters the surge state is determined as the instability boundary point of the engine test device; The aerodynamic instability boundary of the compression system at the current speed is determined according to the parameters of the engine test device in the last working state.

[0088] Since the stator blades 131 of the test turbine 13 rotate step by step at a set small angle until the compression system enters the surge state, there is a one-to-one correspondence between the working state of the engine test device and the position of the stator blades 131 of the test turbine 13. Therefore, the last working state before the compression system enters the surge state is the instability boundary point of the engine test device. Therefore, the various parameters of the engine test device in the last working state before the compression system enters the surge state are the aerodynamic instability boundary of the compression system under the whole engine environment. Among them, the outlet pressure of the compressor and other important physical quantities (such as temperature, etc. as required) can be used as the aerodynamic instability boundary measured under this working condition.

[0089] In some exemplary embodiments, before rotating the stator blades 131 of the test turbine 13 to a calibrated initial position, the method further includes: The stator blades 131 of the test turbine 13 are controlled to rotate repeatedly, and different positions of the stator blades 131 during the rotation process are calibrated; The position of the stator blades 131 of the test turbine 13 is the same as the position of the stator blades 131 of the original turbine, and is calibrated as the initial position.

[0090] Before ignition start, the position of the stator blades 131 is calibrated by repeatedly rotating the stator blades 131, so as to accurately obtain the aerodynamic instability boundary of the compression system in the subsequent test process.

[0091] In addition, the position of the stator blades 131 is calibrated in detail (for example, the position of the stator blades 131 is calibrated every time the stator blades 131 rotate 1°), so that the stator blades 131 can be controlled to rotate gradually in a relatively small step size during the subsequent test process, so as to accurately obtain the aerodynamic instability boundary of the compression system during the subsequent test process. Otherwise, when the engine test device crosses the boundary for the first time, the movement amplitude of the actuator may be too large, causing the stator blades 131 to rotate too much, so that the dynamic static pressure of the compressor changes greatly before the boundary, making it impossible to confirm the specific boundary point. At this time, it is necessary to adjust the test turbine and re-approach the boundary, resulting in the need to approach the boundary multiple times. The above problem can be solved by calibrating the position of the stator blades 131 in detail so that the stator blades 131 can rotate gradually in a relatively small step size, so that the specific instability boundary point can be accurately obtained by approaching the boundary a few times (for example, once).

[0092] The following is an example of a small turbojet engine equipped with a first-stage centrifugal compressor to explain the method for determining the aerodynamic instability boundary of the compression system in the whole machine environment of the present application. Figure 8 As shown, the following steps may be included: Step S302: Install the test turbine onto the original engine body, and rotate the stator blades of the test turbine to a calibrated initial position.

[0093] Based on a fully manufactured engine, the compressor 11, combustion chamber 12, tail nozzle 14, and duct system components of the engine are kept unchanged (i.e. the original engine body), and the turbine components are improved. The typical structural diagram of the improved design is shown in the figure below. Figures 2 to 5 As shown. The key point of the improved design is to design each blade (stator blade 131) of the turbine stator component that was originally fixed to be rotatable along a vertical shaft 1321 that passes through the centroid of the key section of the turbine stator blade 131. The blade shaft 1321 needs to be installed on the inner and outer flow channel walls of the airflow channel at the corresponding position of the turbine stator blade 131, and the inner and outer flow channel walls are subjected to high-temperature resistant lubrication treatment at the position corresponding to the shaft 1321, so as to ensure the reliability and sealing of the shaft 1321 while also ensuring that the shaft 1321 is easy to rotate. The shaft 1321 of the stator blade 131 should extend radially outward from the engine, passing through the turbine outer casing and the engine casing to the periphery of the engine. The shafts 1321 of all stator blades 131 should be connected to an actuating ring 1322 through a multiple-degree-of-freedom transition structure. The specific structure is as shown in Figure 4 and Figure 5 The actuating ring 1322 is centered and fixed in the axial direction relative to the engine casing by means of three-point centering (i.e., the rotation axis is fixed and cannot move in the axial direction). The specific structure is as follows Figure 3As shown, and maintained to be able to rotate in the circumferential direction. The actuating ring 1322 is driven by a single driving assembly 1350, such as a push rod actuated by a stepping motor.

[0094] After the modification, the geometry of the stator blades 131 of the modified turbine is consistent with the geometry of the stator blades 131 of the original turbine except for the area near the connection with the rotating shaft 1321. According to the original geometry of the engine, the initial position of the stator blades 131 of the modified variable geometry turbine is calibrated so that the initial position of the variable geometry turbine is equivalent to the geometry of the original turbine. The position of the actuating ring 1322 is repeatedly changed to calibrate the corresponding relationship between the position of the actuating device and the position of the stator blades 131 of the variable geometry turbine. The position of the stator blades 131 can be represented by the angle of rotation relative to the initial position. For example: the calibrated initial position is recorded as 0°, and other positions can be recorded as 1°, 2°, 3°, ..., -1°, -2°, -3°, ..., etc. based on the initial position. The positive and negative angles are related to the rotation direction of the stator blades 131. In order to make the compressor 11 enter the surge state, the stator blades 131 can be driven to rotate in the direction of reducing the flow cross-sectional area of ​​the test turbine 13. In order to make the compressor 11 exit the surge state, the stator blades 131 may be driven to rotate in a direction to increase the flow cross-sectional area of ​​the test turbine 13 .

[0095] Finally, the stator blades 131 of the test turbine 13 are rotated to the calibrated initial position, and then the next step is performed.

[0096] Step S304: Ignite and start the engine test device, and accelerate to the speed required for the breath test according to the normal experimental process.

[0097] Fix the engine test device on the test bench, ensure that the stator blades 131 of the test turbine 13 are located at the calibrated initial position, and use the engine start control law before modification to ignite the engine test device and push it to the slow speed. Keep the position of the stator blades 131 of the test turbine 13 unchanged, and use the engine acceleration control law before modification to gradually accelerate the engine test device. If the exhaust temperature of the turbine is measured to exceed the limit value during the acceleration process, the engine is decelerated to the slow speed, and the flow cross-sectional area of ​​the test turbine 13 is reduced, and then the acceleration is continued until it is accelerated to the minimum speed required for the panting test.

[0098] Step S306: Rotate the stator blades at a set angle to reduce the flow cross-sectional area of ​​the test turbine.

[0099] Keep the engine test device at the speed required for surge testing, and gradually rotate the stator blades 131 of the test turbine 13 in steps of 1° to gradually reduce the flow cross-sectional area of ​​the test turbine 13. In the process of rotating the stator blades 131, maintain the smooth operation of the actuator. The actuation time for each 1° rotation of the stator blades 131 should not be shorter than 1s to ensure the accuracy of the operation of the actuator. The actuator uses a stepper motor or other actuating device that can achieve precise control, and detects the position of the actuating ring 1322 through an additional sensor to achieve closed-loop control with the control device. As the test proceeds, the exact angle of the stator blades 131 of the variable geometry turbine should be recorded at each moment.

[0100] Step S308: Dynamically collect the compressor outlet pressure parameters for determining whether the compressor enters a surge state.

[0101] Several dynamic static pressure probes are arranged at the outlet of the compressor 11. In order to capture the surge signal and the details of the change of static pressure during a typical surge cycle, the arranged dynamic static pressure probes have high-frequency acquisition capabilities, and the acquisition frequency is not less than 10kHz. The dynamic static pressure probes are arranged along the circumference of the outlet of the compressor 11, and the number is not less than three, so as to obtain the periodicity of the pressure signal along the circumferential rotation. In order to improve the measurement accuracy, a dynamic pressure probe can also be arranged at the inlet of the compressor 11 to obtain the dynamic pressure at the inlet of the compressor 11 and verify it with the dynamic pressure probe at the outlet. The acquisition system of the dynamic pressure probe should be arranged according to the general dynamic pressure acquisition mode. Data interaction with the variable geometry turbine positioning system can be set up to calibrate the corresponding moment of the angle of the stator blade 131 of the variable geometry turbine with the moment of the dynamic pressure acquisition system to ensure the accuracy of the parameters obtained at the same time.

[0102] When the engine test device is started, the measurement and acquisition system of the dynamic pressure probe is started synchronously, and the results of the dynamic pressure acquisition system are monitored at all times.

[0103] Step S310: Determine whether the compressor is gasping according to conditions P1, P2, and P3.

[0104] If any two of P1, P2, and P3 are satisfied, it is determined that the compressor 11 has entered a surge state. If any two of P1, P2, and P3 are not satisfied, the process returns to step S306 to continue reducing the flow cross-sectional area of ​​the variable geometry turbine, and the process repeats until the compressor 11 enters a surge state.

[0105] P1 conditions: The dynamic pressure signal measured at the outlet of the compressor 11 is averaged circumferentially, and the high-frequency and low-frequency signals are filtered out using a filter function. The processed dynamic pressure signal is recorded as P. On this basis, the curvature of the P change process is calculated as of changes, including: ; In the formula, It represents the slope of the curve of the physical quantity P, that is, it represents the speed of the change of the physical quantity P; W represents the window length for calculating the slope, which is a positive integer; It represents the change of the physical quantity P within the time length W; f represents the sampling frequency.

[0106] Determine whether the first instability boundary condition is met: ; In the above formula, The slope of the physical quantity P at time N is A, and A represents the threshold value of the compressor 11 with different configurations. Indicates the flow rate of the compressor 11.

[0107] P2 conditions: The dynamic pressure signal measured at the outlet of the compressor 11 is averaged circumferentially, and the high-frequency and low-frequency signals are filtered out using a filter function. The main periodic signal frequency in the dynamic pressure signal is extracted using real-time fast Fourier transform. .

[0108] According to the current working state of the engine, the parameters such as engine flow rate and pressure obtained by measurement or model calculation are combined with the geometric characteristic parameters of the engine itself to calculate and predict the Helmholtz frequency of the engine entering the surge state at this time. . The calculation formula is: In the above formula, represents the speed of sound at the outlet of the compressor 11, is the equivalent cross-sectional area of ​​the outlet of compressor 11, is the equivalent volume of the combustion chamber 12, is the equivalent length of the combustion chamber 12.

[0109] Determine whether the second instability boundary condition is met: ; In the above formula, is a constant ， It is usually selected according to the specific configuration, size and power level of the engine compressor 11. The meaning of this formula is that when the main periodic frequency of the dynamic change of the outlet pressure of the compressor 11 is close to the Helmholtz frequency, the P2 condition is established.

[0110] P3 conditions: If a low-frequency humming sound is heard during the operation of the engine that is obviously different from the normal operating state, or a continuous explosion sound is heard, or a flame is observed at the engine outlet, then the P3 condition is considered to be met.

[0111] During the test monitoring process, if the collected engine operation information meets any two of P1, P2, and P3, it is determined that the engine has reached the instability boundary at this moment, and the step S12 is continued. If any two of P1, P2, and P3 are not met, the step S306 is returned to continue to reduce the flow cross-sectional area of ​​the variable geometry turbine until the compressor 11 of the engine successfully enters the surge state.

[0112] In this embodiment, according to the engine structure type, main cycle parameters and based on previous test data, the parameters A related to the aerodynamic instability criterion of the engine compressor 11 are selected as 15 kPa / s and B is selected as 0.1. According to the main geometric dimensions and operating parameters of the engine, it is calculated that at the current measured speed =85Hz, at time N of the test, the monitored Reached 15kPa / s, and measured =82Hz, at this time it is found that the P1 and P2 conditions are met, and it is determined that the engine compressor 11 enters the surge state.

[0113] Step S312: Collect instability boundary data and perform instability boundary measurement tests at other rotation speeds.

[0114] After determining that the compressor 11 of the engine has successfully entered the surge state, the flow cross-sectional area of ​​the variable geometry turbine should be rapidly increased until the original design angle, i.e., the calibrated initial position, is reached. If the engine operating state still meets any of the above-mentioned P1, P2, and P3 conditions at this time, the flow cross-sectional area of ​​the variable geometry turbine should continue to be increased and the engine fuel injection amount should be reduced until the engine operating state does not meet the P1, P2, and P3 conditions at all, so that the engine exits the surge state.

[0115] If the test is only planned to measure the instability boundary at a single speed, the engine is stopped and the test is ended according to the general process. If the test is still planned to measure the instability boundary at other speeds, the engine is accelerated to the lowest speed among the remaining speeds to be measured, and steps S306 to S3012 are repeated to complete the measurement.

[0116] At each measuring speed, the working state of the engine test device at the last variable geometry angle before the determination condition in step S310 is met during the process of reducing the flow cross-sectional area of ​​the variable geometry turbine is recorded. The engine parameters under this working state are used as the aerodynamic instability boundary of the compressor 11 under the complete engine environment obtained through the variable geometry turbine test.

[0117] The collected instability boundary data include: the pressure and temperature of the compressor 11 outlet section, the pressure and temperature of the compressor 11 inlet section, and may also include the temperature of the turbine outlet section, the vibration of the engine in three directions, the engine thrust, fuel consumption, speed and other parameters.

[0118] Fig.11 The whole machine instability boundary obtained by this method is shown. The black track in the figure is the whole process of the surge condition of the compressor 11 under the whole machine environment obtained by this method, and the gray circle is the instability boundary point determined by this method.

[0119] In summary, the method for determining the aerodynamic instability boundary of a compressor under the whole machine environment provided by the embodiment of the present application, by using the variable geometry turbine method to make the compressor reach a surge state under the whole machine environment, obtain the surge dynamic process, and obtain the instability boundary point by calculating the change process of physical parameters, has the following beneficial effects: Compared with the traditional fuel step gasping and high-pressure gas charging gasping methods, this method realizes gasping in a quasi-steady-state process, so it can standardize the description of the aerodynamic instability boundary of the compressor under the whole machine environment, and based on this gasping method, the deviation range and direction of other different gasping methods can be given, which is convenient for comparison between the aerodynamic instability boundaries of the compression components of engines of different sizes and designs obtained under different gasping methods.

[0120] Compared with the existing whole machine test method of using fuel step mode to force the surging, this method will not cause additional burden on the turbine and compressor components, thereby greatly enhancing the safety of the whole machine surging test and reducing the cost of the whole machine surging test.

[0121] Compared with the existing whole machine test method of using high-pressure gas to force breathing, this method does not require large-scale modifications to the tester and surrounding equipment, thereby shortening the test preparation cycle and reducing costs.

[0122] Compared with the existing method of using whole machine simulation to obtain the aerodynamic instability boundary in the whole engine environment, this method eliminates the influence of the error caused by the simulation modeling method on the prediction of the aerodynamic instability boundary of the compressor in the whole machine environment. The aerodynamic instability boundary in the whole engine environment can be obtained more accurately.

[0123] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0124] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0125] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0126] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0127] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0128] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present application.

[0129] The processor may be an integrated circuit chip with signal processing capabilities. The above-mentioned processor may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present invention may be implemented or executed. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0130] In any one or more of the above exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on a computer-readable medium or transmitted via a computer-readable medium as one or more instructions or codes, and executed by a hardware-based processing unit. A computer-readable medium may include a computer-readable storage medium corresponding to a tangible medium such as a data storage medium, or a communication medium that facilitates a computer program, such as any medium transmitted from one place to another according to a communication protocol. In this way, a computer-readable medium may generally correspond to a non-temporary tangible computer-readable storage medium or a communication medium such as a signal or carrier wave. A data storage medium may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures for implementing the technology described in the present disclosure. A computer program product may include a computer-readable medium.

[0131] By way of example and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage devices, magnetic disk storage devices or other magnetic storage devices, flash memory or any other medium that can be used to store the desired program code in the form of instructions or data structures and can be accessed by a computer. Moreover, any connection may also be referred to as a computer-readable medium. For example, if instructions are transmitted from a website, server or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technologies such as infrared, radio and microwave, then coaxial cable, fiber optic cable, double-stripe line, DSL or wireless technologies such as infrared, radio and microwave are included in the definition of medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carriers, signals or other transient (transient) media, but are directed to non-transient tangible storage media. As used herein, disks and optical disks include compact disks (CDs), laser optical disks, optical optical disks, digital versatile disks (DVDs), floppy disks or Blu-ray disks, etc., where disks typically reproduce data magnetically, and optical disks use lasers to reproduce data optically. Combinations of the above should also be included within the scope of computer-readable media.

[0132] For example, instructions may be executed by one or more processors such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Therefore, the term "processor" as used herein may refer to any of the above structures or any other structures suitable for implementing the techniques described herein. In addition, in some aspects, the functionality described herein may be provided in dedicated hardware and / or software modules configured for encoding and decoding, or incorporated in a combined codec. Furthermore, the techniques may be fully implemented in one or more circuits or logic elements.

[0133] The technical solutions of the embodiments of the present disclosure can be implemented in a wide variety of devices or equipment, including wireless mobile phones, integrated circuits (ICs) or a group of ICs (e.g., chipsets). Various components, modules or units are described in the embodiments of the present disclosure to emphasize the functional aspects of the devices configured to perform the described technologies, but they do not necessarily need to be implemented by different hardware units. Instead, as described above, the various units can be combined in a codec hardware unit or provided by a collection of interoperable hardware units (including one or more processors as described above) in combination with appropriate software and / or firmware.

Claims

1. A test turbine, characterized in that: Used to replace the original turbine in the whole-machine surge test of the engine, the stator blades of the test turbine are configured as rotatable blades so that the flow cross-sectional area of ​​the test turbine can be reduced by rotating the stator blades, so that the compression system of the engine can enter a surge state.

2. The test turbine according to claim 1, characterized in that: The test turbine further comprises an actuating device, the actuating device being connected to the stator blades of the test turbine and configured to drive the stator blades to rotate; The actuating device comprises: a plurality of rotating shafts and a driving mechanism; The number of the stator blades is multiple, and the multiple rotating shafts are arranged one by one corresponding to the multiple stator blades of the test turbine; each of the rotating shafts extends along the radial direction of the test turbine and is connected to the corresponding stator blade, and is configured to drive the corresponding stator blade to rotate around the rotating shaft; The driving mechanism is connected to the multiple rotating shafts and is configured to drive the multiple rotating shafts to rotate synchronously so as to synchronously adjust the working angles of the multiple stator blades.

3. The test turbine according to claim 2, characterized in that: The central axis of any of the rotating shafts passes through the centroid of the maximum stress cross section of the corresponding stator blade; and / or An air flow channel is provided in the test turbine, and the multiple stator blades are located in the air flow channel and are configured to adjust the flow cross-sectional area of ​​the air flow channel by rotation; the two ends of any one of the rotating shafts are rotatably connected to the radial inner wall surface and the radial outer wall surface of the air flow channel; the driving mechanism is located on the outside of the air flow channel; the multiple rotating shafts penetrate the radial outer wall surface of the air flow channel and are connected to the driving mechanism.

4. The test turbine according to claim 3, characterized in that: The driving mechanism comprises: a plurality of adapter structures with multiple degrees of freedom, an actuating ring and a driving assembly; The plurality of adapter structures correspond to and are connected to the plurality of rotating shafts one by one, and are configured to drive the plurality of rotating shafts to rotate synchronously; the actuating ring is rotatably sleeved on the radial outer side of the airflow channel, and is connected to the plurality of adapter structures, and is configured to be able to rotate relative to the airflow channel around the central axis of the actuating ring, so as to drive the plurality of adapter structures to move, so that the plurality of adapter structures respectively drive the corresponding rotating shafts to rotate; the driving assembly is connected to the actuating ring, and is configured to drive the actuating ring to rotate; The driving assembly includes a power source and a transmission mechanism. The power source is connected to the transmission mechanism. The transmission mechanism is connected to the actuating ring and is configured to drive the actuating ring to rotate.

5. The test turbine according to claim 4, characterized in that: The transfer structure comprises: a connecting rod connected to the rotating shaft and a multi-degree-of-freedom bearing connected to the connecting rod; the multi-degree-of-freedom bearing is connected to the actuating ring and is configured to drive the connecting rod to move under the drive of the actuating ring, so that the connecting rod drives the corresponding rotating shaft to rotate; The multi-degree-of-freedom bearing comprises: a first transmission shaft connected to the actuating ring, a roller connected to the first transmission shaft, a second transmission shaft connected to the roller, and the second transmission shaft is connected to the connecting rod; at least one of the connection relationship between the actuating ring and the first transmission shaft, the connection relationship between the first transmission shaft and the roller, the connection relationship between the roller and the second transmission shaft, and the connection relationship between the second transmission shaft and the connecting rod is set to a movable connection relationship with multiple degrees of freedom, so that the rotation of the actuating ring can drive the connecting rod to move; The power source is a stepper motor, at least one of the connecting rods is provided with an actuating hole, and the transmission mechanism includes a push rod, which is inserted into the actuating hole and fits with the actuating hole with a clearance, and is configured to: be able to move linearly and push the connecting rod to rotate under the drive of the stepper motor, so that the connecting rod drives the actuating ring to rotate through the multi-degree-of-freedom bearing.

6. An engine test device, characterized in that: The whole machine breathing test of the engine, the engine test device comprises: the original engine body and the test turbine as claimed in any one of claims 1 to 5; The engine body comprises a compression system, a combustion chamber and a tail nozzle, and the compression system, the combustion chamber, the test turbine and the tail nozzle are connected in sequence.

7. A method for determining the aerodynamic instability boundary of a compression system in a whole machine environment, characterized in that: The whole machine breathing test is carried out using the engine test device as claimed in claim 6, the method comprising: Rotating the stator blades of the test turbine to a calibrated initial position; at the initial position, the stator blades of the test turbine are in the same position as the stator blades of the original turbine; Ignite and start the engine test device, and accelerate it to a set speed for the whole machine breathing test; controlling the stator blades of the test turbine to rotate gradually to reduce the flow cross-sectional area of ​​the test turbine until the compression system enters a surge state; An instability boundary point of the engine test device is determined, and the aerodynamic instability boundary of the compression system at a current rotation speed is determined according to the instability boundary point.

8. The method for determining the aerodynamic instability boundary of a compression system under the whole machine environment according to claim 7, characterized in that: In the step of controlling the stator blades of the test turbine to rotate gradually to reduce the flow cross-sectional area of ​​the test turbine until the compression system enters a surge state, it is determined that the compression system enters a surge state based on that the operation information of the engine test device satisfies the determination condition for entering a surge state; The operation information of the engine test device includes: a physical quantity used to characterize the performance of the compression system, and a signal used to characterize the operation state of the engine test device; The judgment condition for entering the surge state includes at least one of the following: a physical quantity used to characterize the performance of the compression system satisfies a set surge condition, and a signal used to characterize the operating state of the engine test device contains a set surge signal.

9. The method for determining the aerodynamic instability boundary of a compression system under a whole machine environment according to claim 8, characterized in that: The set gasping condition includes at least one of the following: the curvature change of the physical quantity meets the first set instability boundary condition, and the frequency of the periodic signal extracted according to the physical quantity meets the second set instability boundary condition; The set gasping signal includes at least one of a light signal and a sound signal.

10. The method for determining the aerodynamic instability boundary of a compression system under a whole machine environment according to any one of claims 7 to 9, characterized in that: In the step of controlling the stator blades of the test turbine to rotate gradually to reduce the flow cross-sectional area of ​​the test turbine, the stator blades are controlled to rotate by a set angle each time, and the time required for the stator blades to rotate by the set angle is not less than a set time, so that the stator blades rotate smoothly; the set angle is 1°, and the set time is not less than 1s; and / or Before rotating the stator blades of the test turbine to the calibrated initial position, the method further includes: controlling the stator blades of the test turbine to rotate repeatedly, and calibrating different positions of the stator blades during the rotation process; The position of the stator blades of the test turbine is the same as that of the stator blades of the original turbine, which is calibrated as the initial position.

Images