Low-speed wind tunnel complex flow field adjusting device and method

Abstract

The invention discloses a low-speed wind tunnel complex flow field adjusting device and method. The device comprises a grid type fan support and an axial flow fan. The grid type fan support is fixedly installed in the wind tunnel, and a rectangular frame of the grid type fan support is tightly attached to the inner wall face of the wind tunnel. A plurality of fan installation grid holes are evenly formed in the grid type fan support, an axial flow fan is fixedly installed in each fan installation grid hole, and the central axes of all the axial flow fans are distributed in parallel. The method comprises the following steps: numbering the axial flow fans; meshing and dividing the cross section of the wind tunnel flow field to form a plurality of flow field wind speed unit areas, wherein the flow field wind speed unit areas are the same as the fan mounting grid holes in number and are in one-to-one correspondence with the fan mounting grid holes in position; numbering the flow field wind speed unit areas; arranging wind speed sensors at multiple points in the wind tunnel test section; all axial flow fans are synchronously started, and the flow field wind speed is determined; establishing a relation curve between the rotating speed of the axial flow fan and the wind speed of the flow field; setting a test flow field and completing calibration; and correspondingly starting all the axial flow fans according to a calibration result, so that the test flow field is adjusted to a set state.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind tunnel tests, and particularly relates to a device and method for adjusting a complex flow field in a low-speed wind tunnel. Background Art

[0002] Currently, the methods for adjusting the wind tunnel flow field are mainly divided into two categories. One is the traditional mechanical adjustment method, and the other is the active flow control method. For the traditional mechanical adjustment method, it can be further divided into the deflector / grille adjustment method and the variable cross-section test section adjustment method. For the active flow control method, it can be further divided into the synthetic jet control method and the plasma excitation control method.

[0003] When the deflector / grille adjustment method is adopted, the angle of the deflector / opening of the grille can be adjusted manually or electrically, so as to change the wind tunnel flow field. However, this adjustment method has the disadvantages of low adjustment accuracy and slow response speed. The adjustment accuracy error can reach about ±5%, the response speed is only at the second level, and dynamic flow field adjustment cannot be achieved.

[0004] When the variable cross-section test section adjustment method is adopted, the cross-sectional shape of the wind tunnel test section can be changed to change the wind tunnel flow field. However, this adjustment method is only applicable to high-speed wind tunnels for Mach numbers, and the adjustment range is very limited. At the same time, it also has the disadvantages of complex mechanical structure and high cost.

[0005] When the synthetic jet control method is adopted, a micro actuator can be used to generate a pulsed jet, and then used to control the boundary layer of the flow field, so as to achieve flow field adjustment, and it has a response speed of milliseconds. However, this control method has the problem of limited control force and is only applicable to local flow control.

[0006] When the plasma excitation control method is adopted, dielectric barrier discharge can be used to generate plasma, and then used to change the wind tunnel flow field. However, this control method has the problem of low power, and the technology maturity is still relatively low. Summary of the Invention

[0007] Aiming at the problems existing in the prior art, the present invention provides a device and method for adjusting a complex flow field in a low-speed wind tunnel, which have the characteristics of high adjustment accuracy, fast response speed, simple structure, low cost and high technology maturity, and can realize the adjustment of any complex flow field in a low-speed wind tunnel.

[0008] To achieve the above object, the present invention adopts the following technical solution: A complex flow field regulating device for a low-speed wind tunnel, comprising a grid-type fan support and an axial-flow fan; the grid-type fan support is fixedly installed inside the wind tunnel, and the rectangular frame of the grid-type fan support is closely attached to the inner wall surface of the wind tunnel; a plurality of fan installation grid holes are evenly arranged on the grid-type fan support, and an axial-flow fan is fixedly installed in each fan installation grid hole, and the central axes of all axial-flow fans are parallelly distributed.

[0009] A complex flow field regulating method for a low-speed wind tunnel, which adopts the above-mentioned complex flow field regulating device for a low-speed wind tunnel, comprises the following steps:

[0010] Step 1: Number the axial-flow fans. The axial-flow fan in the first fan installation grid hole in the upper left corner of the grid-type fan support is numbered as Z 11 ; in the horizontal direction, the numbers of the axial-flow fans in each horizontal row increase sequentially from left to right; in the vertical direction, the numbers of the axial-flow fans in each vertical column increase sequentially from top to bottom; and so on, until the axial-flow fan in the first fan installation grid hole in the upper right corner of the grid-type fan support is numbered as Z 1N ; the axial-flow fan in the first fan installation grid hole in the lower left corner of the grid-type fan support is numbered as Z N1 ; the axial-flow fan in the first fan installation grid hole in the lower right corner of the grid-type fan support is numbered as Z NN ;

[0011] Step 2: Divide the cross-section of the wind tunnel flow field into grids, so that several flow field wind speed unit areas are formed in the grids of the wind tunnel flow field cross-section. The number of flow field wind speed unit areas is the same as the number of fan installation grid holes and they are in one-to-one correspondence in position;

[0012] Step 3: Number the flow field wind speed unit areas. The first flow field wind speed unit area in the upper left corner of the grid of the wind tunnel flow field cross-section is numbered as F 11 ; in the horizontal direction, the numbers of the flow field wind speed unit areas in each horizontal row increase sequentially from left to right; in the vertical direction, the numbers of the flow field wind speed unit areas in each vertical column increase sequentially from top to bottom; and so on, until the first flow field wind speed unit area in the upper right corner of the grid of the wind tunnel flow field cross-section is numbered as F 1N ; the first flow field wind speed unit area in the lower left corner of the grid of the wind tunnel flow field cross-section is numbered as F N1 ; the first flow field wind speed unit area in the lower right corner of the grid of the wind tunnel flow field cross-section is numbered as F NN ;

[0013] Step 4: Arrange the wind speed sensors in a multi-point distribution manner in the test section of the wind tunnel, and the area of the region where the wind speed sensors are arranged is not less than 70% of the total area of the wind tunnel flow field cross-section;

[0014] Step 5: Simultaneously start all the axial fans on the grid-type fan support, and uniformly increase the rotational speed of all the axial fans from 0 to the rated maximum speed at a constant speed; meanwhile, simultaneously measure the flow field wind speed by all the wind speed sensors, then calculate the average value of the data obtained by all the wind speed sensors, and take this average value as the final measured value of the flow field wind speed;

[0015] Step 6: Based on the rotational speed of the axial fans and the final measured value of the flow field wind speed, establish a relationship curve between the rotational speed of the axial fans and the flow field wind speed;

[0016] Step 7: Set the test flow field, and at the same time calibrate the set test flow field to determine the test rotational speed of each axial fan;

[0017] Step 8: Start all the axial fans corresponding to the calibrated test flow field, and make all the axial fans operate at their determined test rotational speeds, thereby adjusting the test flow field to the set state, and the flow field adjustment is completed.

[0018] In Step 7, the calibration steps of the test flow field are as follows:

[0019] Step ①: Set the regional wind speed of all the flow field wind speed unit areas within the cross-sectional grid of the wind tunnel flow field, and form the required test flow field within the range of the cross-sectional grid of the wind tunnel flow field by all the set regional wind speeds;

[0020] Step ②: Select at least five flow field wind speed calibration points, one of which is the central calibration point, and the remaining flow field wind speed calibration points are circumferential calibration points. The circumferential calibration points are evenly distributed along the circumferential direction of the central calibration point, and the calibration area of all the flow field wind speed calibration points is not less than 70% of the total cross-sectional area of the wind tunnel flow field;

[0021] Step ③: Install wind speed sensors at the selected flow field wind speed calibration points;

[0022] Step ④: According to the relationship curve established between the rotational speed of the axial fans and the flow field wind speed, convert all the set regional wind speeds into the corresponding test rotational speeds of the axial fans;

[0023] Step ⑤: Start all the axial fans synchronously according to the converted test rotational speeds, and at the same time measure the real-time wind speed of the flow field wind speed calibration points by the installed wind speed sensors. If the error value between the measured wind speed and the set regional wind speed does not exceed the design range, the calibration is completed; if the error value between the measured wind speed and the set regional wind speed exceeds the design range, correct the test rotational speed of the axial fans until the error value reaches the design range, and then the calibration is completed.

[0024] The beneficial effects of the present invention:

[0025] The low-speed wind tunnel complex flow field adjustment device and method of the present invention have the characteristics of high adjustment accuracy, fast response speed, simple structure, low cost, and high technology maturity, and can realize the adjustment of any complex flow field in a low-speed wind tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of a low-speed wind tunnel complex flow field adjustment device of the present invention;

[0027] Figure 2 It is a schematic diagram of the numbering of axial flow fans;

[0028] Figure 3 It is a schematic diagram of the numbering of the flow field wind speed unit areas;

[0029] Figure 4 It is a curve graph of the relationship between the rotational speed of the axial flow fan and the flow field wind speed;

[0030] In the figure, 1 - grid-type fan support, 2 - axial flow fan, 3 - fan installation grid hole, 4 - wind tunnel flow field cross-section grid, 5 - flow field wind speed unit area. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] As Figure 1 shown, a low-speed wind tunnel complex flow field adjustment device includes a grid-type fan support 1 and an axial flow fan 2; the grid-type fan support 1 is fixedly installed inside the wind tunnel, and the rectangular frame of the grid-type fan support 1 is closely attached to the inner wall surface of the wind tunnel; a plurality of fan installation grid holes 3 are uniformly arranged on the grid-type fan support 1, and an axial flow fan 2 is fixedly installed in each fan installation grid hole 3, and the central axes of all the axial flow fans 2 are parallelly distributed.

[0033] In this embodiment, the number of fan installation grid holes 3 on the grid-type fan support 1 is 81, and the number of axial flow fans 2 is 81.

[0034] A low-speed wind tunnel complex flow field adjustment method uses the above-mentioned low-speed wind tunnel complex flow field adjustment device, and includes the following steps:

[0035] Step 1: As Figure 2 shown, number the axial flow fans 2, and number the axial flow fan 2 in the first fan installation grid hole 3 in the upper left corner of the grid-type fan support 1 as Z 11; Horizontally, the numbers of the axial fans 2 in each row increase sequentially from left to right; vertically, the numbers of the axial fans 2 in each column increase sequentially from top to bottom; and so on until the axial fan 2 in the first fan installation hole 3 in the upper right corner of the grid-type fan support 1 is numbered Z 1N , the axial fan 2 in the first fan installation hole 3 in the lower left corner of the grid-type fan support 1 is numbered Z N1 , the axial fan 2 in the first fan installation hole 3 in the lower right corner of the grid-type fan support 1 is numbered Z NN ;

[0036] In this embodiment, the axial fan 2 in the first fan installation hole 3 in the upper right corner of the grid-type fan support 1 is numbered Z 19 , the axial fan 2 in the first fan installation hole 3 in the lower left corner of the grid-type fan support 1 is numbered Z 91 , the axial fan 2 in the first fan installation hole 3 in the lower right corner of the grid-type fan support 1 is numbered Z 99 ;

[0037] Step 2: Mesh the cross-section of the wind tunnel flow field so that several flow field wind speed unit areas 5 are formed within the wind tunnel flow field cross-section grid 4, and the number of flow field wind speed unit areas 5 is the same as that of the fan installation holes 3 and they are in one-to-one correspondence in position;

[0038] In this embodiment, the number of fan installation holes 3 is 81;

[0039] Step 3: As shown in Figure 3 , number the flow field wind speed unit areas 5, and number the first flow field wind speed unit area 5 in the upper left corner of the wind tunnel flow field cross-section grid 4 as F 11 ; Horizontally, the numbers of the flow field wind speed unit areas 5 in each row increase sequentially from left to right; vertically, the numbers of the flow field wind speed unit areas 5 in each column increase sequentially from top to bottom; and so on until the first flow field wind speed unit area 5 in the upper right corner of the wind tunnel flow field cross-section grid 4 is numbered F 1N , number the first flow field wind speed unit area 5 in the lower left corner of the wind tunnel flow field cross-section grid 4 as F N1 , number the first flow field wind speed unit area 5 in the lower right corner of the wind tunnel flow field cross-section grid 4 as F NN ;

[0040] In this embodiment, the first flow field wind speed unit area 5 in the upper right corner of the wind tunnel flow field cross-section grid 4 is numbered F 19 , the first flow field wind speed unit area 5 in the lower left corner of the wind tunnel flow field cross-section grid 4 is numbered F 91 , the first flow field wind speed unit area 5 in the lower right corner of the wind tunnel flow field cross-section grid 4 is numbered F 99 ;

[0041] Step 4: The wind speed sensors are arranged in a multi-point distribution manner in the wind tunnel test section, and the area of the area where the wind speed sensors are arranged is not less than 70% of the total cross-sectional area of the wind tunnel flow field;

[0042] In this embodiment, the wind speed sensors are arranged in the flow field wind speed unit areas 5 numbered F 22 , F 25 , F 28 , F 52 , F 55 , F 58 , F 82 , F 85 and F 88 ;

[0043] Step 5: Synchronously start all the axial flow fans 2 on the grid-type fan support 1, and the rotational speeds of all the axial flow fans 2 are synchronously increased uniformly from 0 to the rated maximum speed; at the same time, the flow field wind speed is measured synchronously by all the wind speed sensors, and then the average value of the data obtained by all the wind speed sensors is calculated and used as the final measured value of the flow field wind speed;

[0044] In this embodiment, the rated maximum speed of the axial flow fan 2 is �000 r / min, and the flow field wind speed when the axial flow fan 2 is at the rated maximum speed is 25 m / s; a total of 11 wind speed data acquisition points are set, and the rotational speeds of the corresponding axial flow fans 2 are 0 r / min, 800 r / min, 1600 r / min, 2400 r / min, 3200 r / min, 4000 r / min, 4800 r / min, 5600 r / min, 6400 r / min, 7200 r / min and 8000 r / min respectively;

[0045] Step 6: Based on the rotational speed of the axial flow fan 2 and the final measured value of the flow field wind speed, establish a relationship curve between the rotational speed of the axial flow fan 2 and the flow field wind speed, as Figure 4 shown;

[0046] Step 7: Set the test flow field and calibrate the set test flow field at the same time to determine the test rotational speed of each axial flow fan 2; among them, the calibration steps of the test flow field are:

[0047] Step ①: Set the regional wind speed of all the flow field wind speed unit areas 5 in the wind tunnel flow field cross-section grid 4, and the required test flow field is formed by the cooperation of all the set regional wind speeds within the range of the wind tunnel flow field cross-section grid 4;

[0048] In this embodiment, those numbered F 25 , F 35 , F 45 , F 65, F 75 , F 85 , F 52 , F 53 , F 54 , F 65 , F 75 and F 85 The regional wind speeds of the flow field wind speed unit area 5 of F 55 and the flow field wind speed unit area 5 numbered F 15 are respectively set to 13.8 m / s, 12.2 m / s, 13.8 m / s, 13.8 m / s, 12.2 m / s, 13.8 m / s, 16.5 m / s, 18.2 m / s, 16.5 m / s, 16.5 m / s, 18.2 m / s and 16.5 m / s. The regional wind speeds of the remaining flow field wind speed unit areas 5 are uniformly set to 15 m / s, so as to form a gradient change of the wind speed from large to small and then to large between the flow field wind speed unit area 5 numbered F 55 and the flow field wind speed unit area 5 numbered F 95 , and to form a gradient change of the wind speed from small to large and then to small between the flow field wind speed unit area 5 numbered F 55 and the flow field wind speed unit area 5 numbered F 51 , and between the flow field wind speed unit area 5 numbered F 55 and the flow field wind speed unit area 5 numbered F 59 , thus forming a specific complex flow field;

[0049] Step ②: Select at least five flow field wind speed calibration points, one of which is the central calibration point, and the remaining flow field wind speed calibration points are circumferential calibration points. The circumferential calibration points are evenly distributed along the circumferential direction of the central calibration point, and the calibration area of all flow field wind speed calibration points is not less than 70% of the total cross-sectional area of the wind tunnel flow field;

[0050] Step ③: Install wind speed sensors at the selected flow field wind speed calibration points;

[0051] In this embodiment, the flow field wind speed unit areas 5 numbered F 15 , F 55 , F 95 , F 54 and F 58 are used as the selected flow field wind speed calibration points, and wind speed sensors are installed at these five flow field wind speed calibration points;

[0052] Step ④: According to the relationship curve established between the rotational speed of the axial flow fan 2 and the flow field wind speed, convert all the set regional wind speeds into the corresponding test rotational speeds of the axial flow fan 2;

[0053] Step ⑤: Synchronously start all the axial fans 2 at the converted test speed. At the same time, measure the real-time wind speed at the wind speed calibration points of the flow field by the arranged wind speed sensors. If the error value between the measured wind speed and the set regional wind speed does not exceed the design range, the calibration ends; if the error value between the measured wind speed and the set regional wind speed exceeds the design range, correct the test speed of the axial fans 2 until the error value reaches the design range, and then the calibration ends;

[0054] In this embodiment, the design range of the error value between the measured wind speed and the set regional wind speed is ±2%, and the measured wind speeds at the wind speed calibration points of the flow field wind speed unit areas 5 numbered F 15 , F 55 , F 95 , F 54 and F 58 are 15.2 m / s, 15.3 m / s, 14.8 m / s, 15.1 m / s and 14.9 m / s respectively, and the error values are 1%, 2%, -1%, 0.6% and -0.6% respectively, all of which fall completely within the design range of the error value;

[0055] Step Eight: Start all the axial fans 2 corresponding to the calibrated test flow field, and make all the axial fans 2 operate at their determined test speeds, so as to adjust the test flow field to the set state, and the flow field adjustment ends.

[0056] The solutions in the embodiments are not intended to limit the protection scope of the present invention. Any equivalent implementation or modification without departing from the present invention is included in the protection scope of the present invention.

Claims

1. A device for adjusting a complex flow field in a low-speed wind tunnel, characterized in that: It includes a grid-type fan support and axial fans; the grid-type fan support is fixedly installed inside the wind tunnel, and the rectangular frame of the grid-type fan support is closely attached to the inner wall surface of the wind tunnel; a number of fan installation grid holes are evenly arranged on the grid-type fan support, and an axial fan is fixedly installed in each fan installation grid hole, and the central axes of all axial fans are parallelly distributed.

2. A method for adjusting a complex flow field in a low-speed wind tunnel, which uses the device for adjusting a complex flow field in a low-speed wind tunnel described in claim 1, is characterized in that, It includes the following steps: Step 1: Number the axial fans. The axial fan in the first fan installation grid hole in the upper left corner of the grid-type fan support is numbered as Z 11 ; Horizontally, the numbers of the axial fans in each row increase one by one from left to right; vertically, the numbers of the axial fans in each column increase one by one from top to bottom; and so on until the axial fan in the first fan installation grid hole in the upper right corner of the grid-type fan support is numbered as Z 1N , the axial fan in the first fan installation grid hole in the lower left corner of the grid-type fan support is numbered as Z N1 , and the axial fan in the first fan installation grid hole in the lower right corner of the grid-type fan support is numbered as Z NN ; Step 2: Conduct a grid division on the cross-section of the wind tunnel flow field, so that several flow field wind speed unit areas are formed within the grid of the wind tunnel flow field cross-section. The number of flow field wind speed unit areas is the same as that of the fan installation grid holes and their positions correspond one by one. Step 3: Number the flow field wind speed unit areas. Number the first flow field wind speed unit area in the upper left corner of the wind tunnel flow field cross-section grid as F 11 ; In the horizontal direction, the numbering of the flow field wind speed unit areas in each horizontal row increases sequentially from left to right; in the vertical direction, the numbering of the flow field wind speed unit areas in each vertical column increases sequentially from top to bottom; and so on until the first flow field wind speed unit area in the upper right corner of the wind tunnel flow field cross-section grid is numbered as F 1N , number the first flow field wind speed unit area in the lower left corner of the wind tunnel flow field cross-section grid as F N1 , and number the first flow field wind speed unit area in the lower right corner of the wind tunnel flow field cross-section grid as F NN ; Step 4: Arrange the wind speed sensors in a multi-point distribution manner in the test section of the wind tunnel, and the area of the region where the wind speed sensors are arranged is not less than 70% of the total area of the wind tunnel flow field cross-section. Step 5: Synchronously start all the axial fans on the grid-type fan support, and the rotation speeds of all the axial fans increase uniformly from 0 to the rated maximum rotation speed synchronously; at the same time, all the wind speed sensors synchronously measure the wind speed of the flow field, then calculate the average value of the data obtained by all the wind speed sensors, and take this average value as the final measured value of the flow field wind speed. Step 6: Based on the rotation speed of the axial fan and the final measured value of the flow field wind speed, establish a relationship curve between the rotation speed of the axial fan and the flow field wind speed. Step 7: Set the test flow field, and at the same time calibrate the set test flow field to determine the test rotation speed of each axial fan. Step 8: Start all the axial fans corresponding to the calibrated test flow field, so that all the axial fans operate at their respective determined test rotation speeds, and then adjust the test flow field to the set state, and the flow field adjustment is completed.

3. A method for adjusting a complex flow field in a low-speed wind tunnel according to claim 2, characterized in that, In Step 7, the calibration steps of the test flow field are as follows: Step ①: Set the regional wind speeds of all the flow field wind speed unit areas within the grid of the wind tunnel flow field cross-section, and the required test flow field is formed by the set regional wind speeds within the range of the wind tunnel flow field cross-section grid. Step ②: Select at least five flow field wind speed calibration points, one of which is the central calibration point, and the rest are circumferential calibration points. The circumferential calibration points are evenly distributed along the circumferential direction of the central calibration point, and the calibration area of all the flow field wind speed calibration points is not less than 70% of the total area of the wind tunnel flow field cross-section. Step ③: Arrange wind speed sensors at the selected flow field wind speed calibration points. Step ④: According to the established relationship curve between the rotation speed of the axial fan and the flow field wind speed, convert all the set regional wind speeds into the corresponding test rotation speeds of the axial fans. Step ⑤: Synchronously start all the axial fans according to the converted test rotation speeds. At the same time, the wind speed sensors arranged measure the real-time wind speed of the flow field wind speed calibration points. If the error value between the measured wind speed and the set regional wind speed does not exceed the design range, the calibration is completed. If the error value between the measured wind speed and the set regional wind speed exceeds the design range, then correct the test rotation speed of the axial fan until the error value reaches the design range, and the calibration is completed.

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