Test bench and test method for the effect of tip clearance flow on stall in axial compressor

Abstract

Disclosed are a test bench and a test method for the influence of the tip clearance flow of an axial flow compressor on the stall. In the test bench for the influence of the tip clearance flow of an axial flow compressor on the stall, a seven-point total pressure and total temperature composite probe is arranged on the upstream section of the axial flow compressor, a five-point total pressure probe is arranged on the downstream section of the axial flow compressor, a pressure scanning valve connects the pressure measurement channels of the seven-point total pressure and total temperature composite probe and the five-point total pressure probe, a thermocouple collector is connected to the temperature measurement channel of the seven-point total pressure and total temperature composite probe, a laser endoscope is located in the blade path of a stationary blade, laser emitted by a laser generator is projected to the tip clearance of a moving blade via a light guide arm and the laser endoscope to form a plane sheet light, a tracer particle generator is arranged in front of a bell mouth to continuously generate tracer particles sucked into the axial flow compressor, a CCD camera is vertically aligned with the plane sheet light to take an image, and a collection device connects the pressure scanning valve, the thermocouple collector and the CCD camera.

Description

Technical Field

[0001] The invention belongs to the technical field of axial flow compressor testing, in particular to a test bench and a test method for the influence of blade tip clearance flow of an axial flow compressor on stall. Background Art

[0002] The size of the axial compressor of an aircraft engine (especially the tip clearance) is generally small, making it difficult to conduct experimental measurements. Taking the axial compressor of an aircraft engine as the prototype, a low-speed large-scale model is obtained through certain aerodynamic similarity criteria, and its internal flow conditions are similar to those of the prototype. Building a low-speed large-scale axial compressor test bench can achieve high-precision measurements of the compressor's external characteristics and flow details such as the tip clearance flow, providing experimental support for in-depth exploration of the complex flow inside a multi-stage compressor, and providing high-precision basic data for the development of high-confidence flow field prediction methods.

[0003] Mass flow is one of the basic parameters of axial flow compressors, and the measurement accuracy of flow determines the accuracy of the operating point. The axial flow compressor test bench generally adopts the standard differential pressure flowmeter specified in the standard GB / T 2624 (ISO5167), which has the characteristics of simple structure and high measurement accuracy. This type of standard differential pressure flowmeter requires that the flow at the primary device is in a fully developed flow state without vortex, so a long straight pipe section is required upstream of the primary device. In situations where laboratory space is limited, it is often impossible to meet the requirements of the primary device for the length of the upstream straight pipe section, and the flow measured by the standard differential pressure flowmeter will have a certain error.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention proposes a test bench for the influence of the blade tip clearance flow of an axial flow compressor on stall, so that the length of the upstream straight pipe section does not need to meet the requirements of the standard, and high-precision measurement of flow details such as the compressor external characteristics and the blade tip clearance flow can be achieved, and the accuracy of flow measurement can be improved. It has the characteristics of simple structure, precision and reliability, low cost, etc.

[0006] The objective of the present invention is achieved through the following technical solutions: a test bench for the effect of axial compressor tip clearance flow on stall comprises:

[0007] An air intake system, comprising a bell mouth, a venturi tube and a transition duct, wherein the venturi tube is directly connected to the bell mouth upstream and is connected to the casing downstream through the transition duct;

[0008] A drive system, comprising a motor, a frequency converter for controlling the motor speed, and a transmission shaft, wherein the transmission shaft comprises a motor shaft connected to the motor, a coupling connected to the motor shaft, a torque and speed tester provided on the coupling for measuring the torque and speed of the transmission shaft, a main shaft connected to the coupling, a compressor shaft connected to the main shaft via the coupling, and spherical roller bearings and bearing seats provided at both ends of the compressor shaft;

[0009] An axial flow compressor comprising:

[0010] A casing, contained outside the axial compressor;

[0011] The hub is divided into three sections, the first section is an inlet guide vane hub supported by a front support in the casing, the second section is a moving blade hub connected to the compressor shaft, the third section is a stationary blade and outlet guide vane hub supported by a rear support in the casing, and the second section hub is respectively sealed with comb teeth of the first section and the third section hub;

[0012] The moving blade is connected to the moving blade hub, and there is a gap between the moving blade hub and the casing;

[0013] A stationary blade, two ends of which are connected to the casing and the third section hub and are adjacent to the moving blade;

[0014] A measurement system comprising a probe measurement system and a PIV measurement system, wherein:

[0015] A probe measurement system comprising,

[0016] A plurality of measuring holes are evenly distributed in the circumferential direction on the upstream section and the downstream section of the axial flow compressor;

[0017] A seven-point total pressure and total temperature composite probe, which is arranged at the upstream section of the axial flow compressor and includes a pressure measurement channel and a temperature measurement channel;

[0018] a five-point total pressure probe, which is arranged at the downstream section of the axial flow compressor and includes a pressure measurement channel;

[0019] A pressure scanning valve, which connects the pressure measurement channels of the seven-point total pressure and total temperature composite probe and the five-point total pressure probe;

[0020] A thermocouple collector connected to the temperature measurement channel of the seven-point total pressure and total temperature composite probe;

[0021] A PIV measurement system comprising,

[0022] An observation window is arranged at a position of the casing corresponding to the moving blade;

[0023] A laser endoscope located at a blade passage of the stationary blade;

[0024] A laser generator, which emits laser light that is projected to the blade tip gap of the moving blade through a light guide arm and a laser endoscope to form a plane sheet of light;

[0025] a tracer particle generator, which is arranged in front of the bell mouth to continuously generate tracer particles to be sucked into the axial flow compressor;

[0026] A CCD camera, which is aligned vertically with the planar light sheet to capture an image;

[0027] A collection device is connected to the pressure scanning valve, the thermocouple collection instrument and the CCD camera.

[0028] In the test bench for the effect of the axial flow compressor blade tip clearance flow on stall, the axial flow compressor further comprises:

[0029] An inlet guide vane is arranged in the casing and close to one side of the air intake system, the moving blade is adjacent to the inlet guide vane, and the inlet guide vane is connected to the casing and the first section of the hub;

[0030] An outlet guide vane is arranged in the casing and adjacent to the stationary vane, and the outlet guide vane is connected to the casing and the third section hub.

[0031] The test bench for the effect of the axial compressor blade tip clearance flow on stall also includes an exhaust system, which includes a pair of thirty-degree elbows and an electric butterfly valve and an exhaust muffler arranged in sequence after the second thirty-degree elbow.

[0032] In the test bench for the effect of the axial compressor blade tip clearance flow on stall, the torque range of the torque and speed tester is 500 N·m, and the speed range is 4000 rpm.

[0033] In the test bench for the effect of the axial compressor blade tip clearance flow on stall, the stationary blades do not block the optical path of the laser endoscope.

[0034] In the test bench for the effect of the axial compressor blade tip clearance flow on stall, the front part of the hub facing the air intake system has a semi-elliptical guide cap.

[0035] In the test bench for the effect of the axial compressor blade tip clearance flow on stall, the profile of the bell mouth is a quarter ellipse.

[0036] In the test bench for the effect of the axial compressor blade tip clearance flow on stall, the Venturi tube is of a truncated type, and the length of the upstream straight pipe is zero.

[0037] The flow correction method of the test bench for the effect of the axial compressor blade tip clearance flow on stall includes:

[0038] Arrange differential pressure flowmeters and determine their geometric parameters;

[0039] Establishing a simulated relationship curve of differential pressure-flow, wherein the flow inside the test bench is calculated by numerical simulation, and the differential pressure and mass flow are extracted to obtain a simulated relationship curve of the differential pressure and the mass flow;

[0040] Based on the flow calculation method built into the differential pressure transmitter, a display relationship curve between the differential pressure and the mass flow is obtained;

[0041] Each differential pressure corresponds to a simulated mass flow rate and a displayed mass flow rate. The simulated mass flow rate is divided by the displayed mass flow rate to obtain a correction factor. For a series of differential pressures, a correction curve about the displayed mass flow rate and the correction factor is obtained.

[0042] Read the mass flow rate displayed by the differential pressure flowmeter and multiply it by the corresponding correction factor to obtain the corrected mass flow rate.

[0043] The test method for the effect of the axial compressor tip clearance flow on stall based on the flow correction method includes:

[0044] Step 1: Performance curve measurement. After fully opening the electric butterfly valve, start the motor, use a torque-tachometer to measure the torque and speed of the drive shaft, read the flow value displayed by the differential pressure flowmeter and correct it based on the flow correction method; use a total pressure and total temperature probe to measure the total pressure and total temperature distribution along the radial direction of the upstream and downstream sections of the axial compressor, gradually reduce the opening of the electric butterfly valve, repeat the above operation, calculate the efficiency and total pressure ratio at each flow rate, draw a performance curve of mass flow rate and efficiency / total pressure ratio at a constant speed, and find out the mass flow rate corresponding to the highest efficiency and the highest total pressure ratio respectively;

[0045] Step 2: Measure the tip clearance flow under the design working condition and determine the plane to be measured; align the CCD camera vertically to the calibration rake and perform optical calibration, turn on the laser to align the laser emitted by the laser endoscope to the plane to be measured; adjust the opening of the electric butterfly valve to make the axial flow compressor work at the highest efficiency point; turn on and adjust the tracer particle generator, and the CCD camera collects the first data at a specific phase;

[0046] Step 3: Measure the tip clearance flow under near-stall conditions, adjust the opening of the electric butterfly valve to make the axial flow compressor operate at the highest total pressure ratio point; turn on and adjust the tracer particle generator, and use the CCD camera to collect the second data under a specific phase; compare the first data and the second data of the tip clearance flow measured under design conditions and near-stall conditions to obtain the influence of the tip clearance flow of the axial flow compressor on the stall.

[0047] Compared with the prior art, the present invention has the following advantages: the test bench for the influence of the blade tip clearance flow on stall of an axial flow compressor described in the present invention is simple to operate, saves space, does not require a long straight pipe section upstream, and has accurate measurement and good reproducibility; it can accurately measure the flow inside the blade tip clearance, and obtain the influence of the blade tip clearance flow on stall through comparative experiments, providing experimental support for in-depth exploration of the complex flow inside a multi-stage compressor, and providing high-precision basic data for the development of a high-confidence flow field prediction method. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0049] In the attached picture:

[0050] Figure 1 is a schematic structural diagram of a test bench for the effect of axial compressor tip clearance flow on stall according to an embodiment of the present invention;

[0051] Figure 2 is a schematic diagram of the structure of the laser light path of a test bench for the influence of the tip clearance flow of an axial compressor on the stall according to an embodiment of the present invention;

[0052] Figure 3 Schematic diagram of the structure of a PIV measurement system of a test bench for the effect of axial compressor tip clearance flow on stall according to an embodiment of the present invention.

[0053] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0054] The following will refer to the attached Figures 1 to 3 Specific embodiments of the present invention are described in more detail. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0055] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0056] To facilitate understanding of the embodiments of the present invention, further explanation will be given below by taking specific embodiments as examples in conjunction with the accompanying drawings, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0057] For a better understanding, Figures 1 to 3 As shown in the figure, the test bench for the effect of axial compressor tip clearance flow on stall includes:

[0058] An air intake system, comprising a bell mouth 1-1, a venturi tube 1-2 and a transition duct 1-3, wherein the venturi tube 1-2 is directly connected to the bell mouth 1-1 upstream and is connected to the casing 1-4 downstream through the transition duct 1-3;

[0059] An axial flow compressor comprising:

[0060] Receiver 1-4;

[0061] A wheel hub 1-5, which is supported in the casing 1-4 via a front support 1-6 and a rear support 1-7;

[0062] A moving blade 1-9, which is connected to the hub 1-5, and there is a gap between the moving blade 1-9 and the casing 1-4;

[0063] A stationary blade 1-10, which is arranged in the casing 1-4 and adjacent to the moving blade 1-9, and a comb seal is provided between the stationary blade 1-10 and the moving blade 1-9;

[0064] A drive system, comprising a motor 1-15, a frequency converter for controlling the speed of the motor 1-15, and a transmission shaft connecting the motor 1-15 and the moving blade 1-9, wherein the transmission shaft comprises a motor shaft 1-16 connected to the motor 1-15, a coupling 1-17 connected to the motor shaft 1-16, a torque and speed tester 1-18 provided on the coupling 1-17 for measuring the torque and speed of the transmission shaft, a main shaft connected to the coupling 1-17, and a compressor shaft 1-20 connecting the main shaft and the moving blade 1-9 via the coupling 1-17;

[0065] A measurement system comprising a probe measurement system and a PIV measurement system, wherein:

[0066] A probe measurement system comprising,

[0067] A plurality of measuring holes are evenly distributed in the circumferential direction on the upstream section and the downstream section of the axial flow compressor;

[0068] A seven-point total pressure and total temperature composite probe, which is arranged at the upstream section of the axial flow compressor and includes a pressure measurement channel and a temperature measurement channel;

[0069] a five-point total pressure probe, which is arranged at the downstream section of the axial flow compressor and includes a pressure measurement channel;

[0070] A pressure scanning valve, which connects the pressure measurement channels of the seven-point total pressure and total temperature composite probe and the five-point total pressure probe;

[0071] A thermocouple collector connected to the temperature measurement channel of the seven-point total pressure and total temperature composite probe;

[0072] A PIV measurement system comprising,

[0073] An observation window 2-1 is arranged at a position of the casing 1-4 corresponding to the moving blade 1-9;

[0074] A laser endoscope 2-3, which is located in the blade path of the stationary blade 1-10;

[0075] A laser generator, which emits laser light that is projected to the blade tip gaps of the moving blades 1-9 via the light guide arm and the laser endoscope 2-3 to form a plane sheet of light;

[0076] a tracer particle generator 1-22, which is arranged in front of the bell mouth 1-1 to continuously generate tracer particles to be sucked into the axial flow compressor;

[0077] A CCD camera 2-2, which is vertically aligned with the plane light sheet to capture an image;

[0078] A collection device is connected to the pressure scanning valve, the thermocouple collector and the CCD camera 2-2.

[0079] In a preferred embodiment of the test bench for the effect of axial flow compressor blade tip clearance flow on stall, the axial flow compressor further comprises:

[0080] An inlet guide vane 1-8 is arranged in the casing 1-4 and close to one side of the air intake system; a moving vane 1-9 is adjacent to the air intake guide vane, and a comb seal is provided between the moving vane 1-9 and the air intake guide vane;

[0081] The outlet guide vane 1-11 is arranged in the casing 1-4 and adjacent to the stationary blade 1-10.

[0082] In a preferred embodiment of the test bench for the effect of axial compressor blade tip clearance flow on stall, an exhaust system is also included, which includes a pair of thirty-degree elbows 1-12 and an electric butterfly valve 1-13 and an exhaust muffler 1-14 arranged in sequence after the second thirty-degree elbow 1-12.

[0083] In the preferred embodiment of the test bench for the effect of the axial compressor blade tip clearance flow on stall, the torque range of the torque and speed tester 1-18 is 500N·m, and the speed range is 4000rpm.

[0084] In a preferred embodiment of the test bench for the effect of the axial compressor blade tip clearance flow on stall, the stator blades 1-10 do not block the optical path of the laser endoscope 2-3.

[0085] In a preferred embodiment of the test bench for the effect of axial compressor tip clearance flow on stall, the hub 1-5 has a semi-elliptical guide cap facing the front of the intake system.

[0086] In a preferred embodiment of the test bench for the effect of axial compressor blade tip clearance flow on stall, the profile of the bell mouth 1 - 1 is a quarter ellipse.

[0087] In a preferred embodiment of the test bench for the effect of axial compressor tip clearance flow on stall, the Venturi tube 1-2 is of a truncated type, and the length of the upstream straight pipe is zero.

[0088] In a preferred embodiment of the test bench for the effect of the axial flow compressor blade tip clearance flow on stall, the axial flow compressor is further provided with a bearing 1-21 for support.

[0089] In one embodiment, the probe measurement system includes a measuring hole, a seven-point total pressure and total temperature composite probe, a five-point total pressure probe, a pressure scanning valve, a thermocouple collector, a computer and collection software; the measuring hole is located in the upstream and downstream sections of the compressor, and 8 holes are evenly arranged along the circumference. The upstream section measuring hole is arranged with a seven-point total pressure and total temperature composite probe, and the downstream section measuring hole is arranged with a five-point total pressure probe; the pressure measurement channel of the probe is connected to the pressure scanning valve, and the temperature measurement channel is connected to the thermocouple collector, and the collected data is processed and displayed by the collection software. The PIV measurement system includes an observation window 2-1, a laser generator, a light guide arm, a laser endoscope 2-3, a tracer particle generator 1-22, a CCD camera 2-2, a computer and acquisition software; the observation window 2-1 is located on the casing 1-4 of the moving blade 1-9 row; the laser emitted by the laser generator is projected to the tip gap of the moving blade 1-9 through the light guide arm and the laser endoscope 2-3 to form a plane sheet of light; the tracer particle generator 1-22 is located in front of the bell mouth 1-1 and continuously generates tracer particles, which are sucked into the compressor; the CCD camera 2-2 is vertically aligned with the sheet of light to shoot; the collected data is processed and displayed by the acquisition software.

[0090] The flow correction method of the test bench for the effect of the axial compressor blade tip clearance flow on stall includes:

[0091] Arrange differential pressure flowmeters and determine their geometric parameters;

[0092] Establishing a simulated relationship curve of differential pressure-flow, wherein the flow inside the test bench is calculated by numerical simulation, and the differential pressure and mass flow are extracted to obtain a simulated relationship curve of the differential pressure and the mass flow;

[0093] Based on the flow calculation method built into the differential pressure transmitter, a display relationship curve between the differential pressure and the mass flow is obtained;

[0094] Each differential pressure corresponds to a simulated mass flow rate and a displayed mass flow rate. The simulated mass flow rate is divided by the displayed mass flow rate to obtain a correction factor. For a series of differential pressures, a correction curve about the displayed mass flow rate and the correction factor is obtained.

[0095] Read the mass flow rate displayed by the differential pressure flowmeter and multiply it by the corresponding correction factor to obtain the corrected mass flow rate.

[0096] The test method for the effect of the axial compressor tip clearance flow on the stall according to the flow correction method includes:

[0097] Step 1: Performance curve measurement. After fully opening the electric butterfly valve 1-13, start the motor 1-15, use a torque-tachometer to measure the torque and speed of the drive shaft, read the flow value displayed by the differential pressure flowmeter and correct it based on the flow correction method; use a total pressure and total temperature probe to measure the total pressure and total temperature distribution along the radial direction of the upstream and downstream sections of the axial compressor, gradually reduce the opening of the electric butterfly valve 1-13, repeat the above operation, calculate the efficiency and total pressure ratio at each flow rate, draw a performance curve of mass flow rate and efficiency / total pressure ratio at a constant speed, and find out the mass flow rate corresponding to the highest efficiency and the highest total pressure ratio respectively;

[0098] Step 2: Measure the tip clearance flow under the design working condition and determine the plane to be measured; align the CCD camera 2-2 vertically to the calibration rake and perform optical calibration, turn on the laser to align the laser emitted by the laser endoscope 2-3 to the plane to be measured; adjust the opening of the electric butterfly valve 1-13 to make the axial flow compressor work at the highest efficiency point; turn on and adjust the tracer particle generator 1-22, and the CCD camera 2-2 collects the first data at a specific phase;

[0099] Step 3: Measure the tip clearance flow under near-stall conditions, adjust the opening of the electric butterfly valve 1-13, and make the axial flow compressor operate at the highest total pressure ratio point; open and adjust the tracer particle generator 1-22, and the CCD camera 2-2 collects the second data under a specific phase; compare the first data and the second data of the tip clearance flow measured under the design condition and the near-stall condition to obtain the influence of the tip clearance flow of the axial flow compressor on the stall.

[0100] In one embodiment, the test bench intake conditions are normal temperature and pressure, the blocked condition intake flow rate is 25kg / s, the design condition intake flow rate is 20.8kg / s, and the near-stall condition intake flow rate is 18kg / s; the design speed of the axial compressor is 3000rpm, the design power is 75kW, and the design total pressure ratio is 1.034; the radius of the hub 1-5 of the axial compressor is between 119.2 and 263.7, and gradually increases along the flow direction; the radius of the casing 1-4 is 402.5mm, the tip radius of the moving blade 1-9 is 401mm, and the blade top clearance is 1.5mm; the number of blades of the inlet guide vane 1-8, the moving blade 1-9, the stationary blade 1-10, and the outlet guide vane 1-11 are 16, 20, 20, and 16, respectively.

[0101] Considering the possible adverse effects of the tracer particles generated by the tracer particle generator 1-22 on human health, the air flowing through the axial compressor is discharged to the outdoor environment; considering the relatively low total pressure of the axial compressor, in order to reduce the total pressure loss, the test bench does not have an exhaust volute, but uses a pair of 30° elbows to guide the airflow to discharge; considering the limited indoor space, the venturi tube 1-2 is directly connected to the bell mouth 1-1, and the mass flow is corrected by a flow correction method. See the structural diagram of the test bench for details. Figure 1 , including intake system, axial flow compressor, exhaust system, drive system and measurement system.

[0102] The air intake system comprises a bell mouth 1-1, a venturi tube 1-2 and a transition duct 1-3. The venturi tube 1-2 is directly connected to the bell mouth 1-1 upstream and is connected to the axial compressor casing 1-4 downstream through the transition duct 1-3.

[0103] The bell mouth 1-1 profile is a quarter ellipse, which plays a certain rectifying role.

[0104] The Venturi tube 1-2 is designed according to GB / T 2624 (ISO 5167), adopts a "truncated" type, and its upstream straight pipe length is zero, and is used to measure the mass flow rate through the compressor.

[0105] The axial compressor comprises a casing 1-4, a hub 1-5, a front support 1-6, a rear support 1-7, an inlet guide vane 1-8, a moving blade 1-9, a stationary blade 1-10, and an outlet guide vane 1-11. The hub 1-5 and the casing 1-4 are supported by the stationary blade 1-10 and the front support 1-6 and the rear support 1-7. The front part of the hub 1-5 is a semi-elliptical guide cap, which plays a certain rectifying role. The blades along the flow direction are the inlet guide vane 1-8, the moving blade 1-9, the stationary blade 1-10, and the outlet guide vane 1-11 in sequence;

[0106] Among them, the moving blade 1-9 is a rotating part, and the others are stationary parts. The moving blade 1-9 is sealed with the inlet guide vane 1-8 and the stationary blade 1-10 by comb teeth, and a certain gap is left between the moving blade 1-9 and the casing 1-4.

[0107] The exhaust system guides the airflow to be discharged axially through a pair of thirty-degree elbows 1-12, and an electric butterfly valve 1-13 and an exhaust muffler 1-14 are arranged in sequence after the second thirty-degree elbow, and the flow rate is adjusted by controlling the opening of the electric butterfly valve 1-13.

[0108] The drive system includes a frequency converter, a motor 1-15, and a transmission shaft. The frequency converter controls the speed of the motor 1-15, and the motor 1-15 is connected to the moving blades through the transmission shaft;

[0109] The transmission shaft includes a motor shaft 1-16, a coupling 1-17, a torque and speed tester 1-18, a coupling 1-17, a main shaft 1-19, a coupling 1-17, and a compressor shaft 1-20. The torque and speed tester 1-18 is used to measure the torque and speed of the transmission shaft. The torque range of the torque and speed tester 1-18 is 500N·m, the speed range is 4000rpm, and the accuracy level is 0.3.

[0110] The measurement system includes a probe measurement system and a PIV measurement system;

[0111] The probe measurement system includes measuring holes, a seven-point total pressure and total temperature composite probe, a five-point total pressure probe, a pressure scanning valve, a thermocouple collector, a computer and collection software; the measuring holes are located in the upstream and downstream sections of the compressor, and 8 holes are evenly arranged along the circumference. The upstream section measuring holes are arranged with a seven-point total pressure and total temperature composite probe, and the downstream section measuring holes are arranged with a five-point total pressure probe; the pressure measurement channel of the probe is connected to the pressure scanning valve, and the temperature measurement channel is connected to the thermocouple collector, and the collected data is processed and displayed by the collection software.

[0112] The PIV measurement system includes an observation window, a laser generator, a light guide arm, a laser endoscope, a tracer particle generator, a CCD camera, a computer and acquisition software.

[0113] Figure 2The arrangement of the laser endoscope and CCD camera of the PIV system is given. The observation window is located on the casing of the moving blade 1-9, and the line of sight is 45° to the horizontal plane; the laser endoscope 2-3 is located in the blade path of the stationary blade 1-10, and the stationary blade will not block the light path; the laser emitted by the laser generator is projected to the gap between the blade tips of the moving blades through the light guide arm and the laser endoscope 2-3 to form a plane light sheet; the tracer particle generator 1-22 is located in front of the bell mouth 1-1, continuously generating tracer particles that are sucked into the compressor; the CCD camera 2-2 is vertically aligned with the light sheet to shoot; the collected data is processed and displayed by the acquisition software.

[0114] A flow correction method comprises the following steps:

[0115] Step 1: Design a differential pressure flow meter

[0116] Design the differential pressure flowmeter according to GB / T 2624 (ISO 5167) and determine all the geometric parameters of the differential pressure flowmeter.

[0117] Step 2: Establish a simulation relationship curve between differential pressure and flow rate

[0118] The flow inside the actual model is calculated through numerical simulation, and the differential pressure and mass flow are extracted to obtain a simulated relationship curve between the differential pressure and the mass flow.

[0119] Step 3: Establish the display relationship curve of differential pressure-flow

[0120] Using the differential pressure extracted in step 2, according to the flow calculation method of GB / T 2624 (ISO5167) built into the differential pressure transmitter, a display relationship curve between differential pressure and mass flow is obtained.

[0121] Step 4: Create a correction curve

[0122] For each differential pressure, there is a corresponding simulated mass flow rate and a displayed mass flow rate. The simulated mass flow rate is divided by the displayed mass flow rate to obtain a correction factor. Therefore, for a series of differential pressures, a correction curve about the displayed mass flow rate and the correction factor can be obtained.

[0123] Step 5: Correct the flow

[0124] Read the mass flow rate displayed on the instrument and multiply it by the corresponding correction factor to obtain the corrected mass flow rate.

[0125] A test method for the effect of blade tip clearance flow on stall of an axial flow compressor comprises the following steps:

[0126] Step 1: Performance curve measurement

[0127] After fully opening the electric butterfly valve 1-13, start the motor 1-15; after the operation is stable, use the torque and speed tester 1-18 to measure the torque and speed of the transmission shaft, read the flow value displayed on the instrument and make corrections; use the total pressure and total temperature probe to measure the total pressure and total temperature distribution along the radial direction of the upstream and downstream sections of the axial compressor;

[0128] Gradually reduce the opening of the electric butterfly valve 1-13 and repeat the above operation;

[0129] Calculate the efficiency and total pressure ratio at each flow rate, draw a performance curve of mass flow rate and efficiency / total pressure ratio at a constant speed, and find out the mass flow rate corresponding to the highest efficiency and the highest total pressure ratio.

[0130] Step 2: Tip clearance flow measurement under design conditions

[0131] Determine the plane to be measured; remove the observation window 2-1, place the calibration rake on the plane to be measured and then install the observation window 2-1; align the CCD camera 2-2 vertically with the calibration rake, and use DaVis software to perform optical calibration; remove the observation window 2-1, take out the calibration rake and then install the observation window 2-1, turn on the laser to align the laser emitted by the laser endoscope 2-3 to the plane to be measured;

[0132] Adjust the opening of the electric butterfly valve 1-13 to make the axial flow compressor work at the highest efficiency point; open and adjust the tracer particle generator 1-22 to make the particle concentration displayed in the DaVis software within an appropriate range; set the phase in the DaVis software so that the CCD camera only collects data under a specific phase; start collecting data.

[0133] Step 3: Tip clearance flow measurement under near-stall conditions

[0134] Adjust the opening of the electric butterfly valve 1-13 to make the axial flow compressor work at the highest total pressure ratio point; open and adjust the tracer particle generator 1-22 to make the particle concentration displayed in the DaVis software within an appropriate range; set the phase in the DaVis software so that the CCD camera 2-2 only collects data under a specific phase; start collecting data.

[0135] The tip clearance flow measured under design conditions and near-stall conditions is compared to obtain the effect of the tip clearance flow on the stall of the axial flow compressor.

[0136] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present invention, all of which belong to the protection of the present invention.

Claims

1. A test bench for the effect of axial compressor tip clearance flow on stall, characterized in that: These include, An air intake system, comprising a bell mouth, a venturi tube and a transition duct, wherein the venturi tube is directly connected to the bell mouth upstream and is connected to the casing downstream through the transition duct; A drive system, comprising a motor, a frequency converter for controlling the motor speed, and a transmission shaft, wherein the transmission shaft comprises a motor shaft connected to the motor, a coupling connected to the motor shaft, a torque and speed tester provided on the coupling for measuring the torque and speed of the transmission shaft, a main shaft connected to the coupling, a compressor shaft connected to the main shaft via the coupling, and spherical roller bearings and bearing seats provided at both ends of the compressor shaft; An axial flow compressor comprising: A casing, contained outside the axial compressor; The hub is divided into three sections, the first section is an inlet guide vane hub supported by a front support in the casing, the second section is a moving blade hub connected to the compressor shaft, the third section is a stationary blade and outlet guide vane hub supported by a rear support in the casing, and the second section hub is respectively sealed with comb teeth of the first section and the third section hub; The moving blade is connected to the moving blade hub, and there is a gap between the moving blade hub and the casing; A stationary blade, two ends of which are connected to the casing and the third section hub and are adjacent to the moving blade; A measurement system comprising a probe measurement system and a PIV measurement system, wherein: A probe measurement system comprising, A plurality of measuring holes are evenly distributed in the circumferential direction on the upstream section and the downstream section of the axial flow compressor; A seven-point total pressure and total temperature composite probe, which is arranged at the upstream section of the axial flow compressor and includes a pressure measurement channel and a temperature measurement channel; a five-point total pressure probe, which is arranged at the downstream section of the axial flow compressor and includes a pressure measurement channel; The seven-point total pressure and total temperature composite probe and the five-point total pressure probe are manufactured by Dalian Winterner Technology Co., Ltd., and their models are C.SH.7 and P.SH.5 respectively; A pressure scanning valve, which connects the pressure measurement channels of the seven-point total pressure and total temperature composite probe and the five-point total pressure probe; A thermocouple collector connected to the temperature measurement channel of the seven-point total pressure and total temperature composite probe; A PIV measurement system comprising, An observation window is arranged at a position of the casing corresponding to the moving blade; A laser endoscope located at a blade passage of the stationary blade; A laser generator, which emits laser light that is projected to the blade tip gap of the moving blade through a light guide arm and a laser endoscope to form a plane sheet of light; a tracer particle generator, which is arranged in front of the bell mouth to continuously generate tracer particles to be sucked into the axial flow compressor; A CCD camera, which is aligned vertically with the planar light sheet to capture an image; A collection device is connected to the pressure scanning valve, the thermocouple collection instrument and the CCD camera.

2. The test bench for the effect of axial compressor tip clearance flow on stall according to claim 1, characterized in that: Preferably, the axial flow compressor further includes: An inlet guide vane is arranged in the casing and close to one side of the air intake system, the moving blade is adjacent to the inlet guide vane, and the inlet guide vane is connected to the casing and the first section of the hub; An outlet guide vane is arranged in the casing and adjacent to the stationary vane, and the outlet guide vane is connected to the casing and the third section hub.

3. The test bench for the effect of axial compressor tip clearance flow on stall according to claim 1, characterized in that: The invention also comprises an exhaust system, which comprises a pair of thirty-degree elbows and an electric butterfly valve and an exhaust muffler which are sequentially arranged after the second thirty-degree elbow.

4. The test bench for the effect of axial compressor tip clearance flow on stall according to claim 1, characterized in that: The torque range of the torque speed tester is 500N·m and the speed range is 4000rpm.

5. The test bench for the effect of axial compressor tip clearance flow on stall according to claim 1, characterized in that: The stationary blades do not block the optical path of the laser endoscope.

6. The test bench for the effect of axial compressor tip clearance flow on stall according to claim 1, characterized in that: The front portion of the hub facing the air intake system has a semi-elliptical guide cap.

7. The test bench for the effect of axial compressor tip clearance flow on stall according to claim 1, characterized in that: The profile of the bell mouth is a quarter ellipse.

8. The test bench for the effect of axial compressor tip clearance flow on stall according to claim 1, characterized in that: The Venturi tube is of truncated type, and the length of the upstream straight pipeline is zero.

9. The flow correction method of a test bench for the effect of axial compressor tip clearance flow on stall according to any one of claims 1 to 8, characterized in that: These include, Arrange differential pressure flowmeters and determine their geometric parameters; Establishing a simulated relationship curve of differential pressure-flow, wherein the flow inside the test bench is calculated by numerical simulation, and the differential pressure and mass flow are extracted to obtain a simulated relationship curve of the differential pressure and the mass flow; Based on the flow calculation method built into the differential pressure transmitter, a display relationship curve between the differential pressure and the mass flow is obtained; Each differential pressure corresponds to a simulated mass flow rate and a displayed mass flow rate. The simulated mass flow rate is divided by the displayed mass flow rate to obtain a correction factor. For a series of differential pressures, a correction curve about the displayed mass flow rate and the correction factor is obtained. Read the mass flow rate displayed by the differential pressure flowmeter and multiply it by the corresponding correction factor to obtain the corrected mass flow rate.

10. A test method for the effect of axial compressor tip clearance flow on stall based on the flow correction method according to claim 9, characterized in that: These include, Step 1: Performance curve measurement. After fully opening the electric butterfly valve, start the motor, use a torque-tachometer to measure the torque and speed of the drive shaft, read the flow value displayed by the differential pressure flowmeter and correct it based on the flow correction method; use a total pressure and total temperature probe to measure the total pressure and total temperature distribution along the radial direction of the upstream and downstream sections of the axial compressor, gradually reduce the opening of the electric butterfly valve, repeat the above operation, calculate the efficiency and total pressure ratio at each flow rate, draw a performance curve of mass flow rate and efficiency / total pressure ratio at a constant speed, and find out the mass flow rate corresponding to the highest efficiency and the highest total pressure ratio respectively; Step 2: Measure the tip clearance flow under the design working condition and determine the plane to be measured; align the CCD camera vertically to the calibration rake and perform optical calibration, turn on the laser to align the laser emitted by the laser endoscope to the plane to be measured; adjust the opening of the electric butterfly valve to make the axial flow compressor work at the highest efficiency point; Turn on and adjust the tracer particle generator, and the CCD camera collects the first data at a specific phase; Step 3: Measure the tip clearance flow under near-stall conditions and adjust the opening of the electric butterfly valve to make the axial flow compressor operate at the highest total pressure ratio point; The tracer particle generator is turned on and adjusted, and the CCD camera collects the second data at a specific phase; the first data and the second data of the blade tip clearance flow measured under the design condition and the near-stall condition are compared to obtain the influence of the axial compressor blade tip clearance flow on the stall.

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