A Method for Measuring and Correcting the Balance Center of Gravity in Wind Tunnel Force Measurement Tests

Abstract

The present invention discloses a method for measuring and correcting the balance centering in a wind tunnel force measurement test, belonging to the technical field of wind tunnel force measurement. It solves the problem in the prior art that the test result error is relatively large due to the inconsistency between the actual centering of the balance and the theoretical centering position in the traditional balance centering measurement and correction method; in the present invention, the wind tunnel test model is designed and processed to determine the positions of the loading points, load is applied to each loading point, the angle of attack of the balance is adjusted through the support system, and then the normal force and pitching moment are measured by the balance; according to the normal force and pitching moment, the lever arm of the loading point at a fixed angle of attack is obtained, and the actual distance of each loading point from the balance centering along the flow direction is obtained by fitting; according to the difference between the actual distance and the theoretical distance of each loading point from the balance centering along the flow direction, the actual position of the balance centering is obtained. The present invention effectively improves the accuracy of the obtained position of the balance centering and can be applied to the wind tunnel force measurement test.

Description

Technical Field

[0001] The present invention relates to a method for measuring and correcting the centering of a balance, and particularly to a method for measuring and correcting the centering of a balance in a wind tunnel force measurement test, belonging to the technical field of wind tunnel force measurement. Background Art

[0002] The wind tunnel force measurement test is an aerodynamic test carried out in a wind tunnel. It mainly measures the aerodynamic force acting on the aircraft test model or its components by installing a force measurement balance in the wind tunnel test model. The wind tunnel force measurement test is crucial for the development of aircraft.

[0003] The force measurement balance, also known as the wind tunnel balance, is a force measurement sensor specifically used in wind tunnel tests. It is mainly used to measure the forces and moments received by the scaled aircraft model or components in the wind tunnel. By means of coordinate transformation between the balance axis system and the model axis system, the lift, drag, side force, pitch moment, roll moment, yaw moment, etc. of the aircraft model or components are obtained. The force measurement balance used in the force measurement wind tunnel test is the key equipment to ensure the accuracy of the force measurement test data. In the current force measurement wind tunnel test, the common method is to use the theoretical centering of the balance as the actual centering of the balance to calculate the distance between the centering of the balance and the reference point of the model moment, and then obtain the relative relationship between the balance axis system and the model axis system. However, there is a risk that the actual centering of the balance deviates from the theoretical centering due to processing tolerances and other reasons during the processing and manufacturing of the balance. Therefore, the existing method cannot meet the requirements of refined tests.

[0004] In summary, there is a need for a method for measuring and correcting the centering of a balance for wind tunnel force measurement tests, which can accurately obtain the aerodynamic moment data of the aircraft model and measure the actual centering position of the balance. Summary of the Invention

[0005] A brief overview of the present invention is given below to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify the key or important parts of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is only to present certain concepts in a simplified form as a prelude to the more detailed description to be discussed later.

[0006] In view of this, to solve the problem of large errors in test results caused by the inconsistency between the actual centering and the theoretical centering of the balance in the traditional method for measuring and correcting the centering of the balance in the prior art, the present invention provides a method for measuring and correcting the centering of the balance in a wind tunnel force measurement test.

[0007] The technical solution is as follows: A method for measuring and correcting the centering of a balance in a wind tunnel force measurement test, comprising the following steps:

[0008] S1. Design and process the wind tunnel test model, determine the positions of the loading points, and define the actual distance and theoretical distance of the loading points from the balance calibration center along the flow direction;

[0009] S2. Install the support system inside the wind tunnel test model and connect the force measurement test model with the support system;

[0010] S3. Install the force measurement test model on the balance through the support system inside the wind tunnel test model and level the balance;

[0011] S4. Apply loads to each loading point, adjust the angle of attack of the balance through the support system, and then measure the normal force and pitching moment through the balance;

[0012] S5. According to the normal force and pitching moment, obtain the moment arms of the loading points at a fixed angle of attack, and fit to obtain the actual distances of each loading point from the balance calibration center along the flow direction;

[0013] S6. According to the difference between the actual distance and the theoretical distance of each loading point from the balance calibration center along the flow direction, obtain the actual position of the balance calibration center.

[0014] Further, in the above S1, design and process the loading points on the back of the symmetric plane of the wind tunnel test model, and define the loading point numbers around the balance calibration center as j, the theoretical distance of the j-th loading point from the balance calibration center along the flow direction as 、the distance of the j-th loading point from the balance calibration center along the normal direction as 、the actual distance of the j-th loading point from the balance calibration center along the flow direction as , j = 1, 2, 3,..., n. When the loading point is in front of the balance calibration center, > 0, > 0. When the loading point is behind the balance calibration center, < 0, < 0.

[0015] Further, in the above S4, it specifically includes the following steps:

[0016] S41. Load weights at the loading point directly below the balance calibration center, adjust the angle of attack of the balance through the support system, and record the normal force and pitching moment measured by the balance at an angle of attack from -2° to 2° and a sideslip angle of 0°;

[0017] S42. Load weights at the loading point in front of the balance calibration center, adjust the angle of attack of the balance through the support system, and record the normal force and pitching moment measured by the balance at an angle of attack from -2° to 2° and a sideslip angle of 0°;

[0018] S43. Load weights at the loading point behind the balance calibration center. Adjust the angle of attack of the balance through the support system, and record the normal force and pitching moment measured by the balance at an angle of attack from -2° to 2° and a sideslip angle of 0°.

[0019] Further, in the step S5, it specifically includes the following steps:

[0020] S51. At each angle of attack selected from -2° to 2°, obtain the lever arm of the loading point at a fixed angle of attack according to the collected normal force and pitching moment.

[0021] S52. According to the lever arms of the loading points at all fixed angles of attack, obtain the curve of the change of the lever arm with the angle of attack, and then obtain the actual distance of each loading point from the balance calibration center along the flow direction.

[0022] In the step S51, the lever arm of the loading point at a fixed angle of attack is expressed as:

[0023] ;

[0024] ;

[0025] ;

[0026] where i is the angle of attack number, i = 1, 2, 3, 4, 5, G is the weight of the weight, is the angle of attack of the balance, is the i-th angle of attack of the balance, is the pitching moment of the balance at a fixed angle of attack, is the normal force of the balance at a fixed angle of attack;

[0027] In the step S52, the curve of the change of the lever arm with the angle of attack is expressed as:

[0028] .

[0029] Further, in the step S6, it specifically includes the following steps:

[0030] S61. According to the actual distance and the theoretical distance of each loading point from the balance calibration center along the flow direction, obtain the difference between the actual distance and the theoretical distance of the j-th loading point from the balance calibration center along the flow direction ;

[0031] S62. Average the differences between the actual distances and the theoretical distances of all loading points from the balance calibration center along the flow direction to obtain the average value of the differences. Add the theoretical calibration center position of the balance and the average value of the differences to obtain the position of the actual calibration center of the balance.

[0032] In S61, the difference between the actual distance and the theoretical distance of the j-th loading point from the balance calibration center along the flow direction is expressed as:

[0033] .

[0034] The beneficial effects of the present invention are as follows: Through the preliminary design and processing of the wind tunnel test model, the positions of the loading points are determined. Subsequently, the test environment is arranged, and each component is connected to the model. Loads are applied to each loading point, and the balance angle of attack is adjusted through the support system. Then, the normal force and pitching moment at each angle of attack are measured by the balance. According to the normal force and pitching moment, the moment arms of the loading points at a fixed angle of attack are obtained, and the actual distances of each loading point from the balance calibration center along the flow direction are fitted. Finally, based on the difference between the actual distance and the theoretical distance of each loading point from the balance calibration center along the flow direction, the actual position of the balance calibration center is obtained. Based on the accurate actual position of the balance calibration center, the accuracy of the corrected wind tunnel force measurement test data is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0036] Figure 1 is a schematic flow chart of a method for measuring and correcting the balance calibration center in a wind tunnel force measurement test;

[0037] Figure 2 is a loading schematic diagram of a wind tunnel force measurement test;

[0038] Figure 3 is a top view of the loading point arrangement.

[0039] Reference numerals: 1. Wind tunnel test model; 2. Balance; 3. Support system; 4. Weights. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] In order to make the technical solutions and advantages in the embodiments of the present invention clearer and more understandable, the following further details the exemplary embodiments of the present invention with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0041] Refer to Figure 1 and Figure 2 for a detailed description of this embodiment. A method for measuring and correcting the balance calibration center in a wind tunnel force measurement test specifically includes the following steps:

[0042] S1. Design and process the wind tunnel test model, determine the positions of the loading points, and define the actual distance and theoretical distance of the loading points from the balance calibration center along the flow direction;

[0043] S2. Install the support system inside the wind tunnel test model and connect the force measurement test model to the support system;

[0044] S3. Install the force measurement test model on the balance through the support system inside the wind tunnel test model and level the balance;

[0045] Specifically: Connect the balance to the support system, initially level the balance, wire and route the components such as the data acquisition system in the balance and the force measurement test model, install the force measurement test model on the balance and level it again;

[0046] S4. Apply loads to each loading point, adjust the angle of attack of the balance through the support system, and then measure the normal force and pitching moment through the balance;

[0047] S5. According to the normal force and pitching moment, obtain the moment arms of the loading points at a fixed angle of attack, and fit to obtain the actual distances of each loading point from the balance calibration center along the flow direction;

[0048] S6. According to the difference between the actual distance and the theoretical distance of each loading point from the balance calibration center along the flow direction, obtain the actual position of the balance calibration center.

[0049] Furthermore, in S1, design and process the loading points on the back of the symmetry plane of the wind tunnel test model, define the loading point numbers around the balance calibration center as j, the theoretical distance of the j-th loading point from the balance calibration center along the flow direction as 、the distance of the j-th loading point from the balance calibration center along the normal direction as 、the actual distance of the j-th loading point from the balance calibration center along the flow direction as , j = 1, 2, 3,..., n. When the loading point is in front of the balance calibration center, > 0, > 0. When the loading point is behind the balance calibration center, < 0, < 0;

[0050] Specifically, in this embodiment, there are a total of 3 loading points, j = 1, 2, 3. Define the loading point number 1 directly below the balance calibration center as the first loading point, the loading point number 2 in front of the balance calibration center as the second loading point, and the loading point number 3 behind the balance calibration center as the third loading point. Record the theoretical distances of the 3 loading points from the balance calibration center along the flow direction as 、 、 , and the distances of the 3 loading points from the balance calibration center along the normal direction are respectively , , , the actual distances of the three loading points from the balance calibration center along the flow direction are respectively , , .

[0051] Further, in the step S4, it specifically includes the following steps:

[0052] S41. Load weights at the loading point directly below the balance calibration center, adjust the angle of attack of the balance through the support system, and record the normal force and pitching moment measured by the balance at the angle of attack from -2° to 2° (the angle of attack interval taken within this range is 1°) and the sideslip angle of 0°.

[0053] S42. Load weights at the loading point in front of the balance calibration center, adjust the angle of attack of the balance through the support system, and record the normal force and pitching moment measured by the balance at the angle of attack from -2° to 2° (the angle of attack interval taken within this range is 1°) and the sideslip angle of 0°.

[0054] S43. Load weights at the loading point behind the balance calibration center, adjust the angle of attack of the balance through the support system, and record the normal force and pitching moment measured by the balance at the angle of attack from -2° to 2° (the angle of attack interval taken within this range is 1°) and the sideslip angle of 0°.

[0055] Further, in the step S5, it specifically includes the following steps:

[0056] S51. At each angle of attack selected from -2° to 2°, obtain the lever arm of the loading point at a fixed angle of attack according to the collected normal force and pitching moment.

[0057] S52. According to the lever arms of the loading points at all fixed angles of attack, obtain the curve of the change of the lever arm with the angle of attack, and further obtain the actual distances of each loading point from the balance calibration center along the flow direction.

[0058] In the step S51, the lever arm of the loading point at a fixed angle of attack is expressed as:

[0059] ;

[0060] ;

[0061] ;

[0062] where i is the angle of attack number, i = 1, 2, 3, 4, 5, G is the weight of the weight, is the angle of attack of the balance, is the i-th angle of attack of the balance, is the pitching moment of the balance at a fixed angle of attack, The normal force of the balance at a fixed angle of attack;

[0063] In S52, the curve of the variation of the moment arm with the angle of attack is expressed as:

[0064] ;

[0065] Specifically, the moment arms of the loading points at a fixed angle of attack include the moment arm of the first loading point at a fixed angle of attack , the moment arm of the second loading point at a fixed angle of attack , and the moment arm of the third loading point at a fixed angle of attack .

[0066] Furthermore, in S6, it specifically includes the following steps:

[0067] S61. According to the actual distance and the theoretical distance of each loading point from the balance calibration center along the flow direction, obtain the difference between the actual distance and the theoretical distance of the j-th loading point from the balance calibration center along the flow direction ;

[0068] S62. Average the differences between the actual distances and the theoretical distances of all loading points from the balance calibration center along the flow direction to obtain the average value of the differences, and add the balance theoretical calibration center position and the average value of the differences to obtain the position of the balance actual calibration center;

[0069] In S61, the difference between the actual distance and the theoretical distance of the j-th loading point from the balance calibration center along the flow direction is expressed as:

[0070] .

[0071] Although the present invention has been described based on a limited number of embodiments, those skilled in the art in this technical field understand that other embodiments can be envisioned within the scope of the present invention thus described. In addition, it should be noted that the language used in this specification is mainly selected for readability and teaching purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention. Therefore, many modifications and variations are obvious to those of ordinary skill in this technical field without departing from the scope and spirit of the appended claims. For the scope of the present invention, the disclosure of the present invention is illustrative rather than restrictive, and the scope of the present invention is defined by the appended claims.

Claims

1. A method for measuring and correcting the balance centering in a wind tunnel force test, characterized in that: The following steps are involved: S1. Design and process the wind tunnel test model, determine the loading point location, and define the actual and theoretical distances of the loading point from the balance center along the flow direction; S2. Install a support system in the wind tunnel test model and connect the force test model to the support system; S3. Install the force test model on a balance in the wind tunnel test model through a support system and level the balance; S4. Load each loading point, adjust the attack angle of the balance through the support system, and then measure the normal force and pitch moment through the balance; S5. According to the normal force and the pitching moment, the arm of the loading point under the fixed angle of attack is obtained, and the actual distance of each loading point from the balance center along the stream direction is obtained by fitting; S6. According to the difference between the actual distance and the theoretical distance of each loading point from the balance center along the flow direction, the actual position of the balance center is obtained.

2. The balance centering measurement and correction method for wind tunnel force test according to claim 1 is characterized in that: In S1, the loading points are designed and processed on the back of the symmetric surface of the wind tunnel test model, and the loading points located around the balance center are defined as j, and the theoretical distance of the jth loading point from the balance center along the flow direction is , the distance between the jth loading point and the balance center along the normal direction is , the actual distance between the jth loading point and the balance center along the flow direction is , j=1, 2, 3, ..., n, when the loading point is in front of the balance center, >0, >0, when the loading point is behind the balance centering, <0, <0.

3. The balance centering measurement and correction method for wind tunnel force test according to claim 2 is characterized in that: The S4 specifically includes the following steps: S41. Load a weight at the loading point directly below the balance center, adjust the balance angle of attack through the support system, and record the normal force and pitching moment measured by the balance when the angle of attack is between -2° and 2° and the sideslip angle is 0°; S42. Load a weight at the loading point in front of the balance centering, adjust the balance angle of attack through the support system, and record the normal force and pitching moment measured by the balance at an angle of attack of -2° to 2° and a sideslip angle of 0°; S43. Load weights at the loading point behind the balance centering, adjust the balance angle of attack through the support system, and record the normal force and pitching moment measured by the balance when the angle of attack is -2° to 2° and the sideslip angle is 0°.

4. The method for measuring and correcting the balance centering in a wind tunnel force test according to claim 3 is characterized in that: The S5 specifically includes the following steps: S51. At each angle of attack selected from -2° to 2°, according to the collected normal force and pitch moment, obtain the moment arm of the loading point at the fixed angle of attack; S52. According to the arm of the loading point at all fixed angles of attack, a curve of the relationship between the arm and the angle of attack is obtained, and then the actual distance of each loading point from the balance center along the stream direction is obtained; In S51, the force arm of the loading point at the fixed angle of attack It is expressed as: ； ； ； Where i is the angle of attack number, i=1, 2, 3, 4, 5, G is the weight of the weight, is the balance angle of attack, is the i-th balance angle of attack, is the balance pitching moment at a fixed angle of attack, is the balance normal force at a fixed angle of attack; In S52, the relationship curve between the force arm and the angle of attack is It is expressed as: 。 5. The method for measuring and correcting the balance centering in a wind tunnel force test according to claim 4 is characterized in that: The S6 specifically includes the following steps: S61. According to the actual distance and theoretical distance of each loading point from the balance center along the flow direction, the difference between the actual distance and theoretical distance of the jth loading point from the balance center along the flow direction is obtained. ; S62. Average the difference between the actual distance and the theoretical distance of all loading points from the balance center in the flow direction to obtain the average value of the difference, add the average value of the theoretical balance center position and the difference to obtain the actual balance center position; In S61, the difference between the actual distance and the theoretical distance of the jth loading point from the balance center along the flow direction is It is expressed as: 。

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