Method for measuring and analyzing distribution of unsteady pressure field of compressor casing

Abstract

The application provides a compressor casing unsteady pressure field distribution measurement and analysis method, comprising: arranging a plurality of dynamic sensors on a rotor casing to form array measuring points; making a collection system of the dynamic sensors receive a trigger signal to start collection according to set collection parameters to obtain pressure signals under the array measuring points; for a plurality of circumferential measuring points at the same axial position, respectively establishing a spatial axis and a time axis according to a circumferential spatial position of the measuring point and the measured pressure signal time sequence, and establishing a space-time correlation axis by using the correlation; interpolating the pressure signals of the measuring points on the space-time correlation axis, and respectively obtaining a relative coordinate system and an absolute coordinate system under a flow field reconstruction virtual channel through coordinate conversion, and then obtaining the change rule of the transient flow field distribution of the axial position; repeating the above steps to obtain the change rule of the transient flow field distribution of different axial positions, combining the transient flow field distributions of different axial positions, and obtaining the transient two-dimensional distribution of the rotor casing flow field parameters.

Description

Technical Field

[0001] This application belongs to the field of turbomachinery testing technology, and specifically relates to a method for measuring and analyzing the unsteady pressure field distribution of a compressor casing. Background Technology

[0002] The internal flow field of an air compressor is complex, exhibiting strong unsteady and three-dimensional flow characteristics. Particularly near the blade tip walls, shock waves, leakage vortices, corner separation, and their mutual interference exist, significantly impacting the compressor's aerodynamic performance and stability. These complex flows alter the pressure distribution within the compressor casing; therefore, pressure measurement of the compressor casing is a crucial method for analyzing the internal flow field of the compressor.

[0003] Each row of blades in a compressor consists of multiple geometrically identical rotor blades or stator blades. During compressor rotation, each row of rotor blades periodically sweeps the casing and the upstream and downstream stator blades. Therefore, the internal flow field exhibits a periodic timing effect that is strongly correlated with the phase of the blade row.

[0004] like Figure 1 The diagram shows a widely used dynamic testing method for compressor casings in China. This method involves arranging a single row of dynamic pressure sensors 14 in the casing to test the pressure field at the casing. During the test, the rotor blade 11 is located between the upstream stator blade 12 and the downstream stator blade 13. The rotor blade 11 will periodically pass through each dynamic pressure sensor 14. The dynamic pressure sensor 14 will sense the pressure field at the casing when the rotor blade 11 is in different phases (relative to the sensor). The test results of different phases are combined to piece together a complete pressure field distribution at the casing.

[0005] However, the traditional method based on a single row of dynamic pressure sensors and phase-locked measurement, while obtaining the pressure field at the complete blade passage casing, assumes that the flow field at the same relative phase of the rotor blades remains unchanged when the rotor blades are at different phases relative to the upstream and downstream stators. In other words, it assumes that the flow field in the blade passage of the compressor is steady in the rotor coordinate system. In reality, due to the influence of the upstream and downstream stator blades, the flow field differs when the rotor and stator are at different phases. Therefore, the main drawback of the traditional testing method is that it combines the flow fields at different rotor phases relative to the sensor, ignoring the unsteady characteristics of the flow field caused by the phase changes of the upstream and downstream stators (especially when the compressor is under non-design conditions). It cannot simultaneously obtain the flow field changes in the blade passage at different rotor phases, and the synthesized flow field may differ from the actual flow, or even mislead the test analysis.

[0006] like Figure 2As shown, for low-speed large-size compressors, an array sensor test layout scheme can be adopted. An array sensor 24 is arranged around the rotor blade 21 of the upstream stator blade 22 and the downstream stator blade 23. This scheme uses spatial interpolation to obtain the transient pressure flow field of the rotor blade tip casing wall.

[0007] The array-type sensor arrangement method 24 can obtain the transient flow field within the blade passage. However, due to the size limitation of the array-type sensor 24, this method is more practical for some low-speed, large-size compressor model tests. For real engineering test objects, due to their small size, it is difficult to arrange array-type sensors on a large scale. For example, for a low-bypass ratio axial compressor, only 3 to 6 rows of sensors can be arranged circumferentially in each blade passage. The spatial resolution of the spatial interpolation method is relatively low. Figure 3 As shown. Summary of the Invention

[0008] The purpose of this application is to provide a method for measuring and analyzing the unsteady pressure field distribution in a compressor casing, so as to solve or mitigate at least one of the problems in the background art.

[0009] The technical solution of this application is: a method for measuring and analyzing the unsteady pressure field distribution of a compressor casing, the method comprising:

[0010] Step S1: Arrange several dynamic sensors on the rotor casing to form an array of measuring points. The coverage of the array of measuring points in the circumferential direction is set according to the channel width between the upstream and downstream stator blades and adjacent rotor blades. The array of measuring points covers the rotor blade flow field in the axial direction. The acquisition frequency of the dynamic sensors is at least a predetermined multiple of the rotor blade passing frequency.

[0011] Step S2: Using phase-locked acquisition technology, the acquisition system of the dynamic sensor receives a trigger signal and starts acquisition according to the set acquisition parameters to obtain the pressure signal under the array measuring point;

[0012] Step S3: For multiple circumferential measuring points at the same axial position, establish spatial and time axes according to the circumferential spatial position of the measuring points and the timing of the measured pressure signals, and establish a spatiotemporal correlation axis using the correlation between the spatial and time axes.

[0013] Step S4: Interpolate the pressure signals at the measuring points on the spatiotemporal correlation axis, and obtain the virtual channels for reconstructing the flow field in the relative coordinate system and the absolute coordinate system through coordinate transformation, thereby obtaining the variation law of the unsteady flow field distribution at this axial position;

[0014] Step S5: Repeat the dynamic sensor measurement points at different axial positions in steps S1 to S4 to obtain the variation law of unsteady flow field distribution at different axial positions. Combine the unsteady flow field distributions at different axial positions to obtain the transient two-dimensional distribution of rotor casing flow field parameters.

[0015] Furthermore, the array measuring points are set at no less than four in the circumferential direction according to the channel width between adjacent rotor blades.

[0016] Furthermore, the array of measuring points covers the rotor blade flow field in the axial direction, as determined by simulation results.

[0017] Furthermore, the predetermined multiple is ten times.

[0018] Furthermore, the acquisition parameters include sampling frequency, acquisition time, and number of samples.

[0019] The method of this application can reconstruct the transient pressure flow field of the compressor casing, and the accuracy of the reconstructed flow field is greatly improved. It is also applicable to compressors with limited test space or limited number of test points due to structural and strength factors. Attached Figure Description

[0020] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0021] Figure 1 This is a schematic diagram of a test method for a single-row dynamic pressure sensor in a compressor casing in the prior art.

[0022] Figure 2 This is a schematic diagram of the test layout for an array of sensors in a compressor casing in the prior art.

[0023] Figure 3 for Figure 2 The diagram shows the layout effect of the array sensor test in the compressor casing.

[0024] Figure 4 This is a flowchart of the method for measuring and analyzing the unsteady pressure field distribution of the compressor casing in this application.

[0025] Figure 5 This is a schematic diagram of the arrangement of measuring points for the dynamic sensor array in the compressor casing of this application.

[0026] Figure 6 This is a schematic diagram of the spatiotemporal correlation process in this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0028] To address the problems existing in current dynamic pressure testing methods for compressor rotor casings, this application proposes a novel method for measuring the pressure field of compressor casings. This method is based on the temporal and spatial correlation of the dynamic signals collected when compressor rotor blades periodically sweep across sensors. It combines spatiotemporal correlation with sensor array layout and phase-locked acquisition. This method enables the effective identification of unsteady flow fields in compressor rotor blades at different phase states relative to upstream and downstream stator blades using a limited number of sensors, thus solving the engineering application problem of refined dynamic testing of high-load, small-size compressors.

[0029] like Figure 4 As shown, the method for testing the transient pressure field distribution of the compressor casing provided in this application includes the following steps:

[0030] Step S1: Arrange a plurality of dynamic sensors 34 on the rotor casing to form an array of measuring points. The coverage area of ​​the dynamic sensor array measuring points in the circumferential direction (i.e., the rotation direction C of the rotor blades 31) is set according to the width of the channel between the upstream and downstream stator blades and adjacent rotor blades 31, and is typically no less than 4 points. For example, in the embodiment illustrated in this application, the axial measuring points of the dynamic sensor array, set according to the channel width of the upstream and downstream stator blades, are 8 (i.e., measuring points arranged along the length of the rotor blades 31), and the circumferential measuring points of the dynamic sensor array, set according to the channel width between adjacent rotor blades 31, are 5. The dynamic sensor array measuring points can cover the rotor blade flow field in the axial direction (i.e., the airflow direction Q), and can extend 0.1 times the rotor chord length at both the leading and trailing edges of the rotor blades. For example, in the embodiment illustrated in this application, the axial measuring points of the dynamic sensor array that can cover the rotor blade flow field in the axial direction are 4. The dynamic sensor array measuring points are as follows... Figure 5 As shown.

[0031] In this embodiment, the sampling frequency of each of the 34 measuring points of the dynamic sensor is set to be at least 10 times the passing frequency of the rotor blades. For example, in this embodiment of the application, the number of rotor blades corresponding to the measured part of the compressor casing is 40, and the rotor speed is 12000 r / min, then the sampling frequency of the 34 measuring points of the dynamic sensor is at least 80 kHz.

[0032] Step S2: Phase-locked acquisition technology is adopted, that is, every time the rotor blade 31 rotates, the dynamic sensor acquisition system receives the trigger signal and starts to acquire according to the set acquisition parameters (such as sampling frequency, acquisition time, sampling quantity, etc.) to obtain pressure signal data under the array measuring points.

[0033] Step S3: For multiple circumferential measuring points at the same axial position, establish spatial axis X and time axes T1 and T2 respectively according to their circumferential spatial position and the measured pressure signal timing. Utilize the correlation between the spatial axis and the time axis to establish spatiotemporal correlation axes XT1 and XT2, where the slope of spatiotemporal correlation axes XT1 and XT2 depends on the period of the pressure signal.

[0034] Step S4: Interpolate the discrete points on the spatiotemporal correlation axis and obtain the virtual channel VC of the flow field reconstruction in the relative coordinate system and the absolute coordinate system through coordinate transformation, and then obtain the variation law of the transient flow field distribution PD at a certain axial position.

[0035] Step S5: Repeat steps S1 to S4 at dynamic sensor measuring points at different axial positions to obtain the variation law of transient flow field distribution at different axial positions. By combining the transient flow field distributions at different axial positions, the transient two-dimensional (circumferential and axial) distribution of rotor casing flow field parameters can be obtained.

[0036] The method for measuring and analyzing the unsteady pressure field distribution in the compressor casing of this application is based on the fact that when the compressor rotor blades sweep across discrete dynamic sensor measurement points arranged in the blade passage casing, each measurement point will periodically sense the dynamic signal of the flow field change. The dynamic signals have a strong correlation between the phase and time of the rotor and stator blades. Based on this characteristic, this application establishes a spatiotemporal correlated coordinate axis by collecting signals from discrete dynamic sensor measurement points, and then reconstructs the unsteady flow field distribution with high spatial resolution based on a limited number of discrete sensor measurement points.

[0037] The method of this application can reconstruct the transient pressure flow field of the compressor casing, while the first method only obtains the time-averaged flow field distribution. Moreover, the accuracy of the reconstructed flow field obtained by the method of this application is significantly improved compared with the third method. This method has a wide range of applications in engineering compressors, especially for compressors with limited test space or limited number of test points due to structural and strength factors.

[0038] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of measuring and analyzing unsteady pressure field distribution of a compressor casing, characterized by, The method comprises: Step S1, arranging a plurality of dynamic sensors on a rotor casing to form array measuring points, a circumferential coverage range of the array measuring points being set according to a passage width between upstream and downstream stator blades and adjacent rotor blades, the array measuring points covering a rotor blade in an axial direction, and a collection frequency of the dynamic sensors being at least a predetermined multiple of a rotor blade passing frequency; Step S2, using a phase-locked collection technology, causing a collection system of the dynamic sensors to receive a trigger signal to start collection according to set collection parameters, so as to obtain pressure signals under the array measuring points; Step S3, for a plurality of circumferential measuring points at a same axial position, respectively establishing a spatial axis and a time axis according to a circumferential spatial position of the measuring points and a measured pressure signal time sequence, and establishing a time-space correlation axis by using a correlation of the spatial axis and the time axis; Step S4, interpolating the measuring point pressure signals on the time-space correlation axis, and respectively obtaining a relative coordinate system and an absolute coordinate system under a flow field reconstruction virtual passage through coordinate conversion, and further obtaining a variation law of an unsteady flow field distribution at the axial position; Step S5, repeating the dynamic sensor measuring points at different axial positions in steps S1-S4, obtaining variation laws of unsteady flow field distributions at different axial positions, combining the unsteady flow field distributions at different axial positions, and obtaining a transient two-dimensional distribution of rotor casing flow field parameters.

2. The method of claim 1, wherein the method further comprises: The array measuring points are set to be not less than 4 in the circumferential direction according to the passage width between adjacent rotor blades.

3. The method of claim 1, wherein the method further comprises: The array measuring points cover a rotor blade flow field in the axial direction, and each extend 0.1 times a rotor chord length at a leading edge and a trailing edge of the rotor blade.

4. The method of claim 1, wherein the method further comprises: The predetermined multiple is ten or more.

5. The method of claim 1, wherein the method further comprises: The collection parameters include a sampling frequency, a collection time, and a sampling number.

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