A method for measuring roll angle in a continuous roll test of a transient wind tunnel

Abstract

The application discloses a roll angle measurement method for continuous variable roll test of a temporary flush wind tunnel, and belongs to the technical field of wind tunnel testing. The method comprises the following steps: step S1, preliminary preparation, two angle measurement sensors are selected for measurement, and the two angle measurement sensors are installed at a predetermined angle with a mounting platform; step S2, on-site calibration operation; on-site calibration of the angle measurement sensor coefficient is performed in a mode of constant attack angle and variable roll angle; step S3, data interception, discretization and application during step-by-step variable attack angle and continuous variable roll angle test, output voltage values of the two angle measurement sensors are continuously collected during the wind tunnel test, and corresponding roll angles are calculated, and the corresponding roll angle range values of the two angle measurement sensors are intercepted and spliced into a target measurement range as required; compared with a traditional step variable roll and constant roll variable attack angle test mode, the scheme greatly improves test efficiency.

Description

Technical Field

[0001] This invention relates to the field of wind tunnel measurement technology, and in particular to a method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel. Background Technology

[0002] Continuous roll test technology is a commonly used wind tunnel testing method for obtaining the variation of aerodynamic forces / torques of a wind tunnel test model with roll angle. Currently, there are two main types of methods for measuring roll angle:

[0003] The first category is optical methods, including laser spot position reference measurement, laser transmission direction reference measurement, laser phase reference measurement, laser polarization direction reference measurement, polarization modulation, and interferometry. These optical methods achieve high resolution, but are also subject to many interference factors. For example, laser spot position reference measurement is susceptible to mechanical vibration and air disturbance; laser transmission direction reference measurement is affected by the surface quality, temperature, and stress deformation of the reflector; the sensitivity of light intensity detection in laser phase reference measurement is easily affected by the light source and signal-to-noise ratio; and laser polarization direction reference measurement suffers from optical rotation deviation and high instrument costs. Optical video measurement can also be used to measure roll angle, but it requires a multi-camera setup and real-time image data processing capabilities, as well as the installation of markers on the object being measured. In general, optical methods offer high measurement accuracy and broad application prospects in roll angle measurement. However, due to the requirements on optical path travel and measurement environment, they are difficult to apply in wind tunnel experiments with limited measurement space, and these methods are also difficult to synchronize with other signals such as balances and pressure in the wind tunnel.

[0004] The second category is non-optical methods, mainly including electronic levels based on the direction of gravity, combined measurement methods based on the position of a square block, and gyroscope measurement methods. Combined measurement methods are contact-based, inevitably causing deformation errors to the object or workpiece being measured during the measurement process, making it difficult to guarantee measurement accuracy and impossible to achieve real-time monitoring. Gyroscopes exhibit drift, which accumulates over time, leading to a gradual increase in the output angle error. The angle measurement accuracy of traditional electronic levels is insufficient for wind tunnel testing, while the measurement range of high-precision angle sensors is insufficient to meet the large-range roll angle measurement requirements of continuous roll tests in wind tunnels.

[0005] In wind tunnel testing, the test model rotates at low speeds, requiring high accuracy in angle measurement and synchronous acquisition with other sensors. Currently, there are two main methods for measuring the roll angle of wind tunnel test models: encoder measurement (201220364352.1) and grating measurement (a roll angle measurement device for high-speed wind tunnel models: 201510928700.1). These methods integrate the encoder or grating with the roll control mechanism of the wind tunnel test model, assuming that the control angle value of the roll control mechanism is the true roll angle of the test model. However, in actual wind tunnel testing, issues such as the connection between the test model's support rods and the roll control mechanism often lead to a difference between the control angle value of the roll control mechanism and the true angle value of the test model. Furthermore, in this type of measurement, the roll angle measurement sensor is not synchronously acquired with other sensors such as the balance and pressure sensors used in the wind tunnel test, resulting in significant synchronization offset errors during subsequent continuous roll test data processing, affecting the accuracy of aerodynamic data. Summary of the Invention

[0006] The purpose of this invention is to provide a method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel, addressing the above-mentioned shortcomings. This method solves the problems of low accuracy, high cost, and high requirements in existing methods for measuring the roll angle in wind tunnel tests.

[0007] This invention is achieved through the following scheme:

[0008] A method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel includes the following steps:

[0009] Includes the following steps:

[0010] Step S1, Preliminary preparation: Select two angle measuring sensors for measurement and install the two angle measuring sensors at the predetermined angle to the mounting plane;

[0011] Step S2, on-site calibration before the test: On-site calibration of the angle measurement sensor coefficient is performed using a constant angle of attack and variable roll angle.

[0012] Step S3, Data Acquisition, Discretization and Application during Stepped Angle of Attack and Continuous Roll Angle Test: During the wind tunnel test, the output voltage values ​​of two angle measurement sensors are continuously collected, and their corresponding roll angles are calculated. As needed, the roll angle range values ​​corresponding to the two angle measurement sensors are intercepted and stitched together to form the target measurement range.

[0013] In step S1, two angle measurement sensors are selected for measurement, specifically including the following steps: when selecting angle measurement sensors, the optimal linear measurement range of each sensor is greater than half of the total measurement range; the angle measurement sensors must have analog output;

[0014] Specifically, when the roll angle to be measured is γ1 to γ2, the optimal linear measurement interval of the first angle measuring sensor is θ. 11 ~θ 12 The optimal linear measurement curve of the second angle measurement sensor is θ. 21 ~θ 22 Then, there exists θ 12 -θ 11 >(γ2-γ1) / 2, θ 22 -θ 21 >(γ2-γ1) / 2;-90°<θ 11 , θ 21 <0°, 0°<θ 12 , θ 22 <90°.

[0015] The installation of the two angle measuring sensors to the mounting plane at a predetermined angle includes the following steps:

[0016] The angle between the angle measuring sensor and the mounting plane is calculated based on the roll angle range to be measured and the optimal linear measurement range of each angle measuring sensor;

[0017] Specifically, let the angles between the first angle measuring sensor and the second angle measuring sensor and the mounting plane be θ1 and θ2, respectively. Then the range of values ​​for θ1 and θ2 is: 90° + θ 11 ≤θ1≤90°+θ 12 -(γ2-γ1) / 2;(γ2-γ1) / 2-θ 22 ≤θ2≤-θ 21 .

[0018] If the roll angle to be measured during wind tunnel testing is γ1~γ2, then during on-site calibration, the calibration range of the angle measurement sensor should be greater than this range, that is, the minimum roll angle should be less than γ1 and the maximum roll angle should be greater than γ2.

[0019] Each angle measurement sensor has no fewer than three calibration steps, and at least one calibration step is a shared step.

[0020] In step S2, the on-site calibration work before the test is as follows;

[0021] While keeping the angle of attack constant, the test model is rotated to different roll angles by the roll control mechanism of the wind tunnel test model. The output voltage value of each angle measurement sensor is collected by the data acquisition system, and then a table of correspondence between the true roll angle value and the output voltage value of the angle measurement sensor is obtained.

[0022] Specifically, the calibration process is as follows:

[0023] Step S21: The wind tunnel test model roll control mechanism rotates the test model steps to a predetermined roll angle;

[0024] Step S22: Manually measure the actual roll angle of the model using a measuring instrument, and determine whether the actual measured roll angle is the roll angle corresponding to the calibration step; if the two are not equal, rotate the test model and perform manual measurement again until the actual measured angle is equal to the preset roll angle, and then collect the output voltage value of the angle measurement sensor.

[0025] Step S23: Repeat steps S21 and S22 until all preset angles of attack have been collected, and the on-site data collection ends.

[0026] The calibration uses the nonlinear least squares method for on-site sensor calibration; the calibration formula is:

[0027]

[0028] in: , , The coefficient to be calibrated This is the actual angle value. The measured voltage value of the angle measurement sensor;

[0029] By using the actual angle value and measured voltage value corresponding to each angle measurement sensor, the coefficients in the above formula are obtained by solving the nonlinear least squares method, thus obtaining the formula for calculating the roll angle in the continuous variable roll test:

[0030] .

[0031] In step S3, during the wind tunnel test, the output voltage curves U1 and U2 of two angle measurement sensors are continuously acquired by the data acquisition system. The corresponding roll angle curves γ1 and γ2 are calculated, and then the data is truncated.

[0032] When the roll angle measurement range is γ1 to γ2, and the measurement is performed by a combination of two angle measurement sensors, the data from γ1 to the upper limit of the optimal linear measurement range of the first angle measurement sensor and the data from the lower limit of the optimal linear measurement range of the second angle measurement sensor to γ2 are extracted and stitched together to form complete γ1 to γ2 angle data; thus, angle measurement is achieved.

[0033] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0034] (1) Compared with the traditional stepped roll and constant roll angle of attack test methods, this scheme greatly improves the test efficiency and reduces the test cost.

[0035] (2) To address the problem of continuous measurement of roll angle over a wide range, a technical solution was proposed to install two angle measurement sensors inside the model and calibrate the sensor coefficients at different angles of attack. This successfully avoided the problem of electromagnetic interference isolation and shielding caused by motor encoder input and the problem of D / A conversion filtering delay, providing accurate and reliable raw data input for continuous acquisition and discretization of experimental data.

[0036] (3) Angle measurement sensors, balances, pressure sensors, etc. are all collected synchronously using the same data acquisition system, which solves the problem of synchronous measurement of the model roll angle and other sensor signals.

[0037] (4) The angle measurement sensor coefficient is obtained by on-site calibration. Therefore, the requirements for the machining accuracy of the mounting base and the installation accuracy of the sensor are relatively low, and the installation angle range is large.

[0038] (5) Continuous measurement of roll angle strongly supports the development of continuous variable roll wind tunnel testing technology, greatly improving testing efficiency and reducing testing costs. For the problem of complex aerodynamic / torque variation of test models with roll angle, it is desirable to obtain test data with a wide range of roll angles and intervals of a certain angle to analyze the aerodynamic laws of the test model in detail. If the test is carried out in the conventional fixed roll angle variable angle of attack method, the total number of wind tunnel tests will reach hundreds. However, by using the continuous variable roll method during the blowing process, not only can the number of start-up vehicles be reduced to dozens, but the number of sampling points can also be increased to obtain a smoother test curve, which greatly improves the testing efficiency and data precision. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the on-site calibration process for using an angle measurement sensor combination to measure roll angle.

[0040] Figure 2 A schematic diagram illustrating the use of a combination of two angle measurement sensors to measure roll angles from 0 to 180°.

[0041] Figure 3 This is a calibration error diagram of the two angle measurement sensors in Example 2;

[0042] Figure 4 This is a schematic diagram showing the original voltage values ​​of the two angle measuring sensors in Example 2;

[0043] Figure 5 This is a schematic diagram of the angles of the two angle measuring sensors in Example 2. Detailed Implementation

[0044] All features disclosed in this specification, or steps in all methods or processes disclosed herein, may be combined in any way, except for mutually exclusive features and / or steps.

[0045] Any feature disclosed in this specification (including any appended claims and abstract) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0046] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a predetermined orientation, or be constructed and operated in a predetermined orientation. Therefore, they should not be construed as limitations on this invention.

[0047] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.

[0048] Example 1

[0049] like Figures 1-2 As shown, the present invention provides a technical solution:

[0050] A method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel includes the following steps:

[0051] Step S1, preliminary preparation: Select two angle measuring sensors for measurement and install the two angle measuring sensors to the mounting platform at the predetermined angle;

[0052] Step S2, on-site calibration: The angle measurement sensor coefficient is calibrated on-site using a constant angle of attack and variable roll angle method;

[0053] Step S3: Data acquisition, discretization and application during the step-variable angle of attack and continuous roll angle test. During the wind tunnel test, the output voltage values ​​of two angle measurement sensors are continuously collected and their corresponding roll angles are calculated. As needed, the roll angle range values ​​corresponding to the two angle measurement sensors are extracted and stitched together to form the target measurement range.

[0054] This scheme can also use the target angle data obtained by splicing to discretize the data from other sensors synchronously acquired by the data acquisition system; thus obtaining data for calculating aerodynamic / torque parameters in continuous roll tests.

[0055] When conducting a stepped variable angle of attack and continuous variable roll angle test, the calibration method is used to independently calculate the angle measurement sensor coefficients at multiple angles of attack in advance. After the wind tunnel test, the corresponding roll angle is calculated based on the sensor calibration coefficients at different angles of attack.

[0056] This solution is designed for roll angles that are larger than the measurement range of an angle measuring sensor.

[0057] In step S1, two angle measuring sensors are selected for measurement, specifically including the following steps:

[0058] For the selection of angle measurement sensors, a combination of two angle measurement sensors is used to achieve continuous measurement of a large range (≥180°) of roll angle, with each sensor measuring a certain angle range. When selecting angle measurement sensors, the optimal linear measurement range of each sensor should be greater than half of the total measurement range. In actual use, the optimal linear measurement range should be selected according to the actual roll angle range that needs to be measured. The angle measurement sensors must have analog output.

[0059] Specifically, when the roll angle to be measured is γ1 to γ2, the optimal linear measurement interval of the first angle measuring sensor is θ. 11 ~θ 12 The optimal linear measurement curve of the second angle measurement sensor is θ. 21 ~θ 22 Then, there exists θ 12 -θ 11 >(γ2-γ1) / 2, θ 22 -θ 21 >(γ2-γ1) / 2;-90°<θ 11 , θ 21 <0°, 0°<θ 12 , θ 22 <90°.

[0060] The installation of the two angle measuring sensors to the mounting plane at a predetermined angle includes the following steps:

[0061] The angle between the angle measuring sensor and the mounting plane is calculated based on the roll angle range to be measured and the optimal linear measurement range of each angle measuring sensor;

[0062] Specifically, let the angles between the first angle measuring sensor and the second angle measuring sensor and the mounting plane be θ1 and θ2, respectively. Then the range of values ​​for θ1 and θ2 is: 90° + θ 11 ≤θ1≤90°+θ 12 -(γ2-γ1) / 2;(γ2-γ1) / 2-θ 22≤θ2≤-θ 21 .

[0063] For example, when measuring a roll angle within the range of 0 to 180°, the optimal linear measurement range of the two angle sensors should be greater than 90°. The included angle between the mounting planes of the two angle sensors is 180 - θ1 - θ2, where θ1 and θ2 are obtained based on the optimal linear measurement range of the angle sensors. For instance, if the optimal linear measurement range of the first angle sensor is -35° to 60°, then the value range of θ1 is 55° to 60°; if the optimal linear measurement range of the second angle sensor is -40° to 55°, then the value range of θ2 is 35° to 40°.

[0064] In step S2, the on-site calibration operation is as follows:

[0065] While keeping the angle of attack constant, the test model is rotated to different roll angles by the roll control mechanism of the wind tunnel test model. The output voltage value of each angle measurement sensor is collected by the data acquisition system, and then a table of correspondence between the true roll angle value and the output voltage value of the angle measurement sensor is obtained.

[0066] Specifically, the calibration process is as follows:

[0067] Step S21: The wind tunnel test model roll control mechanism rotates the test model steps to a predetermined roll angle;

[0068] Step S22: Manually measure the actual roll angle of the model using a measuring instrument, and determine whether the actual measured roll angle is the roll angle corresponding to the calibration step; if the two are not equal, rotate the test model and perform manual measurement again until the actual measured angle is equal to the preset roll angle, and then collect the output voltage value of the angle measurement sensor.

[0069] Step S23: Repeat steps S21 and S22 until all preset angles of attack have been collected, and the on-site data collection ends.

[0070] Specifically, if the roll angle to be measured during the wind tunnel test is γ1~γ2, then during on-site calibration, the calibration range of the angle measuring sensor should be greater than this range, that is, the minimum roll angle should be less than γ1 and the maximum roll angle should be greater than γ2; and the calibration steps of each angle measuring sensor should be no less than 3, preferably more than 7.

[0071] For example, when using a combination of two angle measurement sensors to measure the roll angle within the range of 0 to 180 degrees, the step number is 2n+5. Each angle measurement sensor corresponds to n+4 sets of data. These n+3 sets of data can be used to calibrate the sensor coefficients. Specific data are shown in the table below:

[0072] Example table of true angle and angle measurement sensor output voltage values

[0073]

[0074] The calibration uses the nonlinear least squares method for on-site sensor calibration; the calibration formula is:

[0075]

[0076] in: , , The coefficient to be calibrated This is the actual angle value. The measured voltage value of the angle measurement sensor;

[0077] By using the actual angle value and measured voltage value corresponding to each angle measurement sensor, the coefficients in the above formula are obtained by solving the nonlinear least squares method, thus obtaining the formula for calculating the roll angle in the continuous variable roll test:

[0078] .

[0079] In step S3, during the wind tunnel test, the data acquisition system continuously acquires the output voltage values ​​U1 and U2 of two angle measurement sensors. The corresponding roll angles γ1 and γ2 can be calculated using the above calculation formula. However, since the data acquisition system acquires full data throughout the entire test process, in addition to the angle values ​​of the corresponding measurement area, it also includes the measurement results of the nonlinear region. Therefore, it is necessary to truncate the data.

[0080] Taking a roll angle measurement range of 0° to 180° as an example, using a combination of two angle measurement sensors, the 0° to 90° data from the γ1 curve and the 90° to 180° data from the γ2 curve are extracted and stitched together to form complete 0° to 180° angle data. This angle data is then used to discretize the sensor data such as balance, total pressure, and static pressure synchronously acquired by the data acquisition system, which can then be used to calculate parameters such as aerodynamic force / torque in continuous variable roll tests.

[0081] Example 2

[0082] This embodiment uses the method described in Embodiment 1 for testing;

[0083] Assuming the roll angle to be measured is in the range of 0° to 180°, two angle measuring sensors of the same model are selected, which utilize their optimal linear measurement range of -60° to 60°, and the two mounting angles of the sensor base are both 60°.

[0084] Twenty-one angle calibration points (-5, 5, 15, 25, 35, 45, 55, 65, 75, 85, 90, 95, 105, 115, 125, 135, 145, 155, 165, 175, 185) were selected to calibrate the coefficients of two angle measuring sensors. Sensor 1 used the first 12 data points, and sensor 2 used the last 12 data points. The calibration errors of the two angle measuring sensors are as follows: Figure 3 As shown, all are less than 0.04°.

[0085] A continuous roll test was conducted using calibrated sensors. The original voltage values ​​of the two sensors measured during the test are as follows: Figure 4 As shown, the corresponding angle values ​​are also as follows. Figure 5 As shown, continuous roll angle measurement from 0 to 180° is achieved through the combination of two sensors.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel, characterized by the following steps: Step S1, Preliminary preparation: Select two angle measuring sensors for measurement and install the two angle measuring sensors at the predetermined angle to the mounting plane; In step S1, two angle measurement sensors are selected for measurement, specifically including the following steps: when selecting angle measurement sensors, the optimal linear measurement range of each sensor is greater than half of the total measurement range; the angle measurement sensors must have analog output; Specifically, when the roll angle to be measured is γ1 to γ2, the optimal linear measurement interval of the first angle measuring sensor is θ. 11 ~θ 12 The optimal linear measurement curve of the second angle measurement sensor is θ. 21 ~θ 22 Then, there exists θ 12 -θ 11 >(γ2-γ1) / 2, θ 22 -θ 21 >(γ2-γ1) / 2;-90°<θ 11 , θ 21 <0°, 0°<θ 12 , θ 22 <90°; In step S1, the installation of the two angle measuring sensors with respect to the mounting plane at a predetermined angle specifically includes the following steps: The angle between the angle measuring sensor and the mounting plane is calculated based on the roll angle range to be measured and the optimal linear measurement range of each angle measuring sensor; Specifically, let the angles between the first angle measuring sensor and the second angle measuring sensor and the mounting plane be θ1 and θ2, respectively. Then the range of values ​​for θ1 and θ2 is: 90° + θ 11 ≤θ1≤90°+θ 12 -(γ2-γ1) / 2; (γ2-γ1) / 2-θ 22 ≤θ2≤-θ 21 ; Step S2, on-site calibration before the test: On-site calibration of the angle measurement sensor coefficient is performed using a constant angle of attack and variable roll angle. Step S3, Data Acquisition, Discretization and Application during Stepped Angle of Attack and Continuous Roll Angle Test: During the wind tunnel test, the output voltage values ​​of two angle measurement sensors are continuously collected, and their corresponding roll angles are calculated. As needed, the roll angle range values ​​corresponding to the two angle measurement sensors are intercepted and stitched together to form the target measurement range.

2. The method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel as described in claim 1, characterized in that: If the roll angle to be measured during wind tunnel testing is γ1~γ2, then during on-site calibration, the calibration range of the angle measurement sensor should be greater than this range, that is, the minimum roll angle should be less than γ1 and the maximum roll angle should be greater than γ2.

3. The method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel as described in claim 2, characterized in that: Each angle measurement sensor has no fewer than three calibration steps, and at least one calibration step is a shared step.

4. The method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel as described in claim 3, characterized in that: In step S2, the on-site calibration work before the test is as follows; While keeping the angle of attack constant, the test model is rotated to different roll angles by the roll control mechanism of the wind tunnel test model. The output voltage value of each angle measurement sensor is collected by the data acquisition system, and then a table of correspondence between the true roll angle value and the output voltage value of the angle measurement sensor is obtained.

5. The method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel as described in claim 4, characterized in that: Specifically, the calibration process is as follows: Step S21: The wind tunnel test model roll control mechanism rotates the test model steps to a predetermined roll angle; Step S22: Manually measure the actual roll angle of the model using a measuring instrument, and determine whether the actual measured roll angle is the roll angle corresponding to the calibration step; if the two are not equal, rotate the test model and perform manual measurement again until the actual measured angle is equal to the preset roll angle, and then collect the output voltage value of the angle measurement sensor. Step S23: Repeat steps S21 and S22 until all preset angles of attack have been collected, and the on-site data collection ends.

6. A method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel as described in any one of claims 1 to 5, characterized in that: The calibration uses the nonlinear least squares method for on-site calibration of the angle measurement sensor; the calibration formula is: in: , , The coefficient to be calibrated This is the actual angle value. The measured voltage value of the angle measurement sensor; By using the actual angle value and measured voltage value corresponding to each angle measurement sensor, the coefficients in the above formula are obtained by solving the nonlinear least squares method, thus obtaining the formula for calculating the roll angle in the continuous variable roll test: 。 7. The method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel as described in claim 1, characterized in that: In step S3, during the wind tunnel test, the output voltage curves U1 and U2 of two angle measurement sensors are continuously acquired by the data acquisition system. The corresponding roll angle curves γ1 and γ2 are calculated, and then the data is truncated.

8. The method for measuring the roll angle in a continuous variable roll test of a transient wind tunnel as described in claim 7, characterized in that: When the roll angle measurement range is γ1 to γ2, and the measurement is performed by a combination of two angle measurement sensors, the data from γ1 to the upper limit of the optimal linear measurement range of the first angle measurement sensor and the data from the lower limit of the optimal linear measurement range of the second angle measurement sensor to γ2 are extracted from the curve of the first angle measurement sensor and stitched together to form complete γ1 to γ2 angle data; thus, angle measurement is achieved.

Images