A two-dimensional dynamic boundary layer probe for measuring the stator-rotor tip end wall of a multi-stage compressor

Abstract

The present invention belongs to the technical field of subsonic two-dimensional flow field parameter measurement, and particularly relates to a two-dimensional dynamic boundary layer probe for measuring the end wall between the rotor and stator of a multi-stage compressor. It includes a probe head, a strut, a dynamic pressure sensor, and a positioning block. The probe head includes a cylinder and a bi-twisted line of revolution body with a common bottom surface, and a dynamic pressure sensor is encapsulated inside. On the side surface of the cylinder of the probe head, a pressure sensing hole is opened, which is communicated with the dynamic pressure sensor encapsulated inside the probe head. The sensor cable is led out of the probe tail through the inner channel of the probe strut, and a positioning block is sleeved on the probe tail. The present invention is calibrated in a calibration wind tunnel and can measure the dynamic changes of two-dimensional flow field parameters in the boundary layer of the end wall between the rotor and stator of a multi-stage compressor. The flow field parameters include the airflow deflection angle, total pressure, static pressure, and Mach number, providing an actual measurement data basis for improving the performance of the compressor. Compared with other boundary layer probes, the probe head of the present invention adopts a bi-twisted line of revolution body structure, the probe head is in an "I" shape, and the vertical distance from the center of the pressure sensing hole to the lowest point of the probe head is relatively small. It has the advantages of self-positioning function, small size, high spatial resolution, can be inserted between the rotor and stator of a multi-stage compressor for measurement, small interference to the measured flow field, high measurement accuracy, and multi-parameter dynamic measurement.

Description

Technical Field

[0001] The present invention belongs to the technical field of subsonic two-dimensional flow field parameter measurement, and particularly relates to a two-dimensional dynamic boundary layer probe for measuring the end wall between the rotor and stator of a multi-stage compressor, which is suitable for measuring the dynamic changes of two-dimensional flow field parameters in the end wall boundary layer between the rotor and stator of a multi-stage compressor. The flow field parameters include the air flow deflection angle, total pressure, static pressure, and Mach number. Background Art

[0002] Obtaining the two-dimensional flow field parameters of the end wall boundary layer between the rotor and stator of a multi-stage compressor plays an important role in improving the performance of the compressor. The end wall boundary layer between the rotor and stator of a multi-stage compressor includes the casing boundary layer and the hub boundary layer. For the measurement of the two-dimensional flow field parameters inside the casing / hub boundary layer between the rotor and stator of a compressor, due to the influence of the wake of the moving blade, leakage vortex, corner vortex, and other secondary flows on the boundary layer flow field, the flow field has strong unsteadiness and vorticity; in addition, the clearance between the rotor and stator of a multi-stage compressor is relatively small, especially the clearance between the rotor and stator of the later stages will be smaller; therefore, there are measurement difficulties such as a large air flow deflection angle, a thin boundary layer thickness, and a narrow measurement space in the measurement of the boundary layer flow field.

[0003] Currently, the measurement of boundary layer flow field parameters can be divided into two methods: contact measurement and non-contact measurement.

[0004] Contact measurement mainly uses measurement methods such as boundary layer probes, hot wires, and dynamic wall static pressure sensors. For a conventional boundary layer probe, since the probe head is L-shaped, it cannot be inserted between the rotor and stator of the compressor for measurement, and there is also a very large cavity effect in the boundary layer probe, which can only obtain the steady-state total pressure value at the measurement point and cannot measure the dynamic changes of the air flow deflection angle, static pressure, and Mach number; according to the insensitivity of the boundary layer probe to the air flow direction, when the flow field deflection angle is large, the boundary layer probe cannot obtain an accurate total pressure value. When using a hot wire probe to measure the boundary layer flow field, usually only one-dimensional flow field dynamic velocity signals can be measured, and it cannot provide dynamic parameter information of the air flow deflection angle, total pressure, static pressure, and Mach number. The dynamic wall static pressure sensor can be installed on the casing surface to measure the dynamic static pressure of the casing boundary layer. Due to the rotation of the hub, the installation of the sensor on the hub surface is restricted, and it is very difficult to measure the dynamic static pressure of the hub boundary layer. Moreover, the dynamic wall static pressure sensor cannot measure the air flow deflection angle, total pressure, and Mach number.

[0005] Non-contact measurement mainly includes particle image velocimetry (PIV), laser Doppler velocimetry (LDV), phase Doppler particle analyzer (PDPA) and pressure sensitive paint (PSP) and other measurement methods. PIV / LDV / PDPA will not interfere with the flow field and is often used to measure the flow field velocity. However, in the process of measuring the boundary layer flow field velocity, there are problems such as wall reflection and low particle concentration, and it is impossible to obtain accurate boundary layer velocity field data. In addition, this type of measurement method cannot provide dynamic change information of total pressure and static pressure. Pressure sensitive paint (PSP) uses the sensitivity of pressure sensitive paint to pressure to obtain the distribution cloud map of dynamic static pressure on the wall, which can reflect the dynamic change of static pressure in the boundary layer of the end wall. However, pressure sensitive paint is a macroscopic measurement method and cannot obtain accurate static pressure values, and it cannot obtain dynamic information of airflow deflection angle, total pressure and Mach number.

[0006] For the measurement of the two-dimensional flow field parameters of the end wall boundary layer in the compressor test, we hope to obtain dynamic information such as the airflow deflection angle, total pressure, static pressure and Mach number of the flow field in the end wall boundary layer during the test, which can be used to verify the compressor design and flow field diagnosis in order to improve the machine performance. However, the above measurement methods cannot meet the current test needs. Summary of the invention

[0007] The technical problem to be solved by the present invention is to measure the dynamic changes of airflow deflection angle, total pressure, static pressure and Mach number in the two-dimensional flow field of the boundary layer of the end wall of the rotor-static compartment of a multi-stage compressor. The present invention provides a two-dimensional dynamic boundary layer probe for measuring the end wall of the rotor-static compartment of a multi-stage compressor. Compared with other boundary layer probes, the present invention has the advantages of self-positioning function, "丨"-shaped probe head, small size, high spatial resolution, can be inserted into the rotor-static compartment for measurement, small interference to the measured flow field, high measurement accuracy and multi-parameter dynamic measurement. The present invention is suitable for measuring the dynamic changes of airflow deflection angle, total pressure, static pressure and Mach number in the two-dimensional flow field in the boundary layer of the end wall of the rotor-static compartment of a multi-stage compressor.

[0008] The technical solution of the present invention is:

[0009] 1. A two-dimensional dynamic boundary layer probe for measuring the stator-rotor end wall of a multistage compressor, which is composed of a probe head (1), a strut (2), a dynamic pressure sensor (6), and a positioning block (8). It is characterized in that: the probe head (1) is a cylinder (3) and a spirograph of a lemniscate of Bernoulli with a common bottom surface. The connection between the cylinder (3) and the spirograph of the lemniscate of Bernoulli (4) is a smooth curved surface transition. A dynamic pressure sensor (6) is encapsulated inside the probe head (1); on the side surface of the cylinder (3) of the probe head (1), a pressure sensing hole (5) is opened, which is a positive hole (5). The positive hole (5) is communicated with the dynamic pressure sensor (6) encapsulated inside the probe head (1); the center line of the positive hole (5) and the axis of the cylinder (3) of the probe head (1) are in the same plane, and the axis of the cylinder (3) of the probe head (1) coincides with the axis of the probe strut (2).

[0010] 2. Further, the diameter of the cylinder (3) of the probe head (1) is d, and the value range is 1.5 mm ≤ d ≤ 2.3 mm, and the length is 4d to 8d.

[0011] 3. Further, the spirograph (4) is formed by rotating the AB curve segment on the lemniscate of Bernoulli around the axis L. Point A is the intersection point of the lemniscate of Bernoulli, and the tangent line at point B is perpendicular to the tangent line at point A. The rotation axis L passes through point A and is perpendicular to the tangent line at point A.

[0012] 4. Further, the diameter of the positive hole (5) is 0.2 mm to 0.4 mm, and the vertical distance between the center of the positive hole (5) and the lowest point on the surface of the spirograph (4) is h, and the value range is 0.29d ≤ h ≤ 0.6d.

[0013] 5. Further, the probe strut (2) is a cylinder with a diameter of D, and the value range is 4 mm ≤ D ≤ 10 mm. A circular pipe is opened inside it. The cable (7) of the dynamic pressure sensor encapsulated inside the probe head (1) is led out of the probe tail through the pipe inside the probe strut (2). A positioning block (8) is sleeved at the probe tail;

[0014] 6. Further, the positioning block (8) is an integral structure, which includes a rectangular base (9), a cylindrical boss (10), a through hole (11), and a threaded hole (12). It is sleeved on the tail of the probe strut through the through hole (11) and is fixed by a countersunk head screw (13) passing through the threaded holes (12) on both sides of the boss (10). The countersunk head screw (13) is completely embedded in the threaded hole (12).

[0015] 7. Furthermore, the rectangular base (9) comprises four rectangular side faces and two square bottom faces, two adjacent side faces of the four side faces are perpendicular to each other, and all four side faces can be used as positioning faces. One bottom face of the base (9) is connected to the cylindrical boss (10), the perpendicular bisector of the bottom face coincides with the axis of the boss (10), the axis of the boss (10) coincides with the center line of the through hole (11), the diameter of the through hole is D+0.05 mm, the outer diameter of the boss is M, and the value range is D+2 mm≤M≤D+5 mm, the side length of the bottom face of the base (9) is M to M+3 mm, and the thickness of the base (9) is H, and the value range is 2 mm≤H≤5 mm.

[0016] The beneficial effects of the present invention are:

[0017] Compared with other boundary layer probes, the present invention is a two-dimensional dynamic boundary layer probe for measuring the end wall of the rotor and stator of a multi-stage compressor, which has the following beneficial effects:

[0018] Beneficial effect 1: The probe head of the present invention adopts a double-twisted wire spiral body structure, and the dynamic pressure sensor can be installed closer to the pressure sensing hole, which greatly reduces the volume of the cavity between the pressure sensing hole and the sensor, reduces the cavity effect, improves the frequency response of the probe, and can measure the dynamic parameters of the flow field; the vertical distance between the center of the pressure sensing hole and the lowest point of the double-twisted wire spiral body surface is small, and the measurement of the two-dimensional flow field parameters inside the end wall boundary layer can be realized, and the parameters include airflow deflection angle, total pressure, static pressure and Mach number; the probe head is "丨"-shaped and has a small size. On the one hand, the probe can be inserted into the rotor-static space of a multi-stage compressor for measurement, and the interference to the measured flow field is small. On the other hand, the probe has a high spatial resolution.

[0019] Beneficial effect two: the double-twisted wire body and the cylindrical body of the probe head have a smooth curved surface transition. When the airflow flows over the surface of the double-twisted wire body, the special structure of the double-twisted wire body can suppress the airflow separation on its surface, and reduce the interference of the flow around the support rod head on the flow field in the boundary layer; in addition, when the flow field parameters are measured close to the end wall, the present invention can suppress the scale of the horseshoe vortex at the front end of the probe head and improve the measurement accuracy.

[0020] Beneficial effect three: The positioning block used in the present invention is small in size and has little impact on the probe during the measurement process. Since the four sides of the positioning block can be used as positioning surfaces and can be replaced with each other, the positioning process is simple and convenient, and is more suitable for actual engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Figure 2 It is the process of forming a lemniscate.

[0023] Figure 3 yesFigure 1 Right side view.

[0024] Figure 4 is Figure 3 Partial enlarged view of...

[0025] Figure 5 is Figure 3 Top view.

[0026] Figure 6 is the test layout diagram of the probe.

[0027] Wherein: 1 - probe head, 2 - probe rod, 3 - cylinder, 4 - surface of revolution formed by lemniscate, 5 - positive hole, 6 - dynamic pressure sensor, 7 - cable of dynamic pressure sensor, 8 - positioning block, 9 - rectangular base, 10 - cylindrical boss, 11 - through hole, 12 - threaded hole, 13 - countersunk screw, 14 - casing, 15 - rotor, 16 - stator, 17 - hub. Specific embodiments

[0028] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] As Figure 1 shown, in this embodiment, a two - dimensional dynamic boundary layer probe for measuring the rotor - stator end wall of a multistage compressor is introduced, which is composed of a probe head (1), a rod (2), a dynamic pressure sensor (6), and a positioning block (8). It is characterized in that: the probe head (1) is a cylinder (3) and a surface of revolution formed by a lemniscate (4) with a common bottom surface, and there is a smooth curved surface transition at the connection between the cylinder (3) and the surface of revolution formed by the lemniscate (4). A dynamic pressure sensor (6) is encapsulated inside the probe head (1); on the side surface of the cylinder (3) of the probe head (1), a pressure sensing hole (5) is opened, which is a positive hole (5), and the positive hole (5) is communicated with the dynamic pressure sensor (6) encapsulated inside the probe head (1); the center line of the positive hole (5) and the axis of the cylinder (3) of the probe head (1) are in the same plane, and the axis of the cylinder (3) of the probe head (1) coincides with the axis of the probe rod (2).

[0030] The diameter of the cylinder (3) of the probe head (1) is 2 mm and the length is 10 mm.

[0031] The surface of revolution (4) is formed by rotating the AB curve segment on the lemniscate around the axis L. Point A is the intersection point of the lemniscate, the tangent at point B is perpendicular to the tangent at point A, and the rotation axis L passes through point A and is perpendicular to the tangent at point A.

[0032] The diameter of the positive hole (5) is 0.3 mm, and the vertical distance between the center line of the positive hole (5) and the lowest point of the surface of the lemniscate surface of revolution (4) is 0.6 mm.

[0033] The probe support rod (2) is a cylinder with a diameter of 6 mm. There is a circular pipe inside it. The cable (7) of the dynamic pressure sensor encapsulated in the probe head (1) is led out of the probe tail through the pipe inside the probe support rod (2). A positioning block (8) is sleeved on the probe tail.

[0034] The positioning block (8) is an integral structure, including a cuboid base (9), a cylindrical boss (10), a through hole (11), and a threaded hole (12). It is sleeved on the probe tail through the through hole (11) and fixed by countersunk head screws (13) passing through the threaded holes (12) on both sides of the boss (10). The countersunk head screws (13) are all embedded in the threaded holes (12).

[0035] The cuboid base (9) includes four rectangular sides and two square bottoms. Two adjacent sides among the four sides are perpendicular to each other. All four sides can be used as positioning surfaces. One bottom surface of the base (9) is connected to the cylindrical boss (10). The perpendicular bisector of the bottom surface coincides with the axis of the boss (10). The axis of the boss (10) coincides with the center line of the through hole (11). The diameter of the through hole is 6.05 mm, the outer diameter of the boss is 9 mm, the side length of the bottom surface of the base (9) is 11 mm, and the thickness of the base (9) is 3 mm.

[0036] The probe is calibrated in a subsonic calibration wind tunnel. One side of the base (9) of the positioning block (8) is selected as the positioning surface. The relative position between the positioning surface of the positioning block (8) and the pressure sensing hole (5) is determined by a spirit level. The positioning block (8) is fixed by the countersunk head screws (13). Under different incoming flow directions and different Mach numbers, the aerodynamic calibration coefficients of the probe are obtained.

[0037] In actual measurement, the probe is installed and fixed on the displacement mechanism. The specific process is as follows: The spirit level is used to adjust the positioning surface of the displacement mechanism to be horizontal. The probe is installed on the displacement mechanism. A spirit level is placed on the positioning surface of the probe positioning block (8). The probe is rotated along the axis of the probe support rod (2). The positioning surface is adjusted to be horizontal through the spirit level. The relative position between the center line of the positive hole (5) and the positioning surface of the displacement mechanism is determined. The probe is fixed on the displacement mechanism; The displacement mechanism for installing the probe is installed on the measured compressor casing (14) through the positioning device. The displacement mechanism is adjusted to insert the probe into a certain radial position in the boundary layer of the hub (17) between the compressor rotor (15) and the stator (16), such as Figure 6 As shown, according to the known average incoming flow direction, the probe is adjusted through the displacement mechanism to align the positive hole (5) with the average incoming flow direction. Taking this position as the reference, the displacement mechanism is used to drive the probe to rotate 1 angle in the counterclockwise and clockwise directions around the axis of the probe support rod (2). The rotation angle is 40°. A total of 3 angular positions are measured. At each angular position, combined with the aerodynamic calibration coefficients of the probe under different incoming flow directions and different Mach numbers obtained in the subsonic calibration wind tunnel, the airflow deflection angle, total pressure, static pressure, and Mach number of the measured flow field are calculated.

[0038] The present invention has a self-positioning function, and the positioning block (8) used is small in size. During the measurement process, the influence on the probe is small. Since the four sides can be used as positioning surfaces and can be replaced with each other, the positioning process is simple and convenient, and is more suitable for practical engineering applications. The double twisted wire body (4) included in the probe head (1) of the present invention can suppress the separation of airflow when it flows over its surface, and reduce the interference of the flow around the support rod head on the flow field in the boundary layer. When measuring close to the end wall, the double twisted wire body (4) can also suppress the scale of the horseshoe vortex at the front end of the probe head (1). This structure improves the measurement accuracy of the boundary layer flow field of the end wall. The present invention comprises only one pressure sensing hole (5), and only one dynamic pressure sensor (6) is encapsulated in the cylinder (3) of the probe head (1). The probe head (1) is in the shape of "丨" and has a small size, has little interference on the measured flow field, has a high spatial resolution, and can be inserted between the rotor (15) and the stator (16) of a multi-stage compressor to measure the dynamic changes of the airflow deflection angle, total pressure, static pressure and Mach number of the two-dimensional flow field of the end wall boundary layer.

Claims

1. A method of using a two-dimensional dynamic boundary layer probe for measuring the end wall between a rotor and a stator of a multi-stage compressor to achieve the measurement of the dynamic changes of two-dimensional flow field parameters within the end wall boundary layer between the rotor and the stator of the multi-stage compressor. The flow field parameters include the airflow deflection angle, total pressure, static pressure, and Mach number. The structure of the two-dimensional dynamic boundary layer probe used for measuring the end wall between the rotor and the stator of the multi-stage compressor consists of a probe head (1), a strut (2), a dynamic pressure sensor (6), and a positioning block (8), and is characterized in that: The probe head (1) is composed of a co-planar cylinder (3) and a surface of revolution formed by a lemniscate, with a smooth surface transition at the connection between the cylinder (3) and the surface of revolution formed by the lemniscate. A dynamic pressure sensor (6) is encapsulated inside the probe head (1). On the side surface of the cylinder (3) of the probe head (1), a through hole (5) is opened, and the through hole (5) is communicated with the dynamic pressure sensor (6) encapsulated inside the probe head (1). The center line of the through hole (5) and the axis of the cylinder (3) of the probe head (1) are in the same plane, and the axis of the cylinder (3) of the probe head (1) coincides with the axis of the probe strut (2). The diameter of the cylinder (3) of the probe head (1) is d, and the value range is 1.5 mm ≤ d ≤ 2.3 mm, with a length of 4d to 8d. The surface of revolution (4) is formed by rotating the AB curve segment on the lemniscate around the axis L. Point A is the intersection point of the lemniscate, the tangent line at point B is perpendicular to the tangent line at point A, and the rotation axis L passes through point A and is perpendicular to the tangent line at point A. The diameter of the through hole (5) is 0.2 mm to 0.4 mm, and the vertical distance from the center of the circle of the through hole (5) to the lowest point on the surface of the surface of revolution (4) is h, with the value range of 0.29d ≤ h ≤ 0.6d. The probe strut (2) is a cylinder with a diameter of D, and the value range is 4 mm ≤ D ≤ 10 mm. A circular pipe is opened inside it. The cable (7) of the dynamic pressure sensor encapsulated inside the probe head (1) is led out of the probe tail through the pipe inside the probe strut (2), and a positioning block (8) is sleeved on the probe tail. The positioning block (8) is an integral structure, including a rectangular parallelepiped base (9), a cylindrical boss (10), a through hole (11), and a threaded hole (12). It is sleeved on the probe tail through the through hole (11) and fixed by a countersunk head screw (13) passing through the threaded holes (12) on both sides of the boss (10). The countersunk head screw (13) is completely embedded in the threaded hole (12). The rectangular parallelepiped base (9) includes four rectangular side surfaces and two square bottom surfaces. Among the four side surfaces, two adjacent side surfaces are perpendicular to each other, and all four side surfaces can be used as positioning surfaces. One bottom surface of the base (9) is connected to the cylindrical boss (10), and the perpendicular bisector of the bottom surface coincides with the axis of the boss (10). The axis of the boss (10) coincides with the center line of the through hole (11). The diameter of the through hole is D + 0.05 mm, and the outer diameter of the boss is M, with the value range of D + 2 mm ≤ M ≤ D + 5 mm. The side length of the bottom surface of the base (9) is M to M + 3 mm, and the thickness of the base (9) is H, with the value range of 2 mm ≤ H ≤ 5 mm. The probe is calibrated in a subsonic calibration wind tunnel. One side surface of the base (9) of the positioning block (8) is selected as the positioning surface, and the relative position between the positioning surface of the positioning block (8) and the through hole (5) is determined by a spirit level. The positioning block (8) is fixed by the countersunk head screw (13). Under different incoming flow directions and different Mach numbers, the aerodynamic calibration coefficients of the probe are obtained. The using steps are as follows. The first step: Use a level to adjust the horizontality of the positioning surface of the displacement mechanism. Install the probe on the displacement mechanism. Place the level on the positioning surface of the probe positioning block (8). Rotate the probe along the axis of the probe support rod (2). Adjust the horizontality of the positioning surface through the level, determine the relative position between the center line of the positive hole (5) and the positioning surface of the displacement mechanism, and fix the probe on the displacement mechanism. The second step: The displacement mechanism equipped with the probe is installed on the measured compressor casing (14) through the positioning device. Adjust the displacement mechanism to insert the probe into a certain radial position in the boundary layer of the compressor casing (14) or the boundary layer of the hub (17) between the compressor rotor (15) and the stator (16). According to the known average incoming flow direction, adjust the probe through the displacement mechanism to align the positive hole (5) with the average incoming flow direction. The third step: Taking this position as the reference, use the displacement mechanism to drive the probe to rotate 1 angle in the counterclockwise and clockwise directions respectively around the axis of the probe support rod (2). The rotation angle is 30° to 45°, and a total of 3 angular positions are measured. The fourth step: At each angular position, combine the probe aerodynamic calibration coefficients obtained in the subsonic calibration wind tunnel at different incoming flow directions and different Mach numbers, and calculate the airflow deflection angle, total pressure, static pressure and Mach number of the measured flow field.

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