Method for correcting temperature effect caused by temperature gradient of wind tunnel balance

Abstract

The invention belongs to the technical field of low-temperature wind tunnel tests, and discloses a method for correcting a temperature effect caused by a temperature gradient of a wind tunnel balance. The temperature effect correction method comprises the steps of obtaining temperature distribution of a wind tunnel balance in a wind tunnel test; acquiring a wind tunnel balance temperature gradient distribution mathematical model; obtaining wind tunnel balance theoretical structure thermal strain and wind tunnel balance theoretical bridge thermal output; obtaining a temperature effect correction formula caused by the temperature gradient; and obtaining corrected aerodynamic force test data. According to the method for correcting the temperature effect caused by the temperature gradient of the wind tunnel balance, the structural deformation caused by the temperature gradient in the wind tunnel balance test and the generated thermal output of the measuring bridge are evaluated through digital simulation, so that the temperature effect caused by the structural temperature gradient of the wind tunnel balance is corrected; the method can effectively improve the data quality of the wind tunnel test, and especially has an engineering practical value for the wind tunnel test with a large flow field temperature change.

Description

Technical Field

[0001] The invention belongs to the technical field of low-temperature wind tunnel tests, and in particular relates to a method for correcting temperature effects caused by a temperature gradient of a wind tunnel balance. Background Art

[0002] Since the material of the wind tunnel balance is sensitive to temperature, temperature changes will cause deformation of the wind tunnel balance, change in measurement zero point and measurement sensitivity. The temperature effect is an important factor affecting the test accuracy of the wind tunnel balance. At present, the processing methods for the change in measurement zero point and measurement sensitivity of the wind tunnel balance caused by temperature are relatively mature, mainly including thermistor compensation, calibration correction and data correction, etc. However, due to the complexity and uncertainty of the temperature gradient, there is no better solution for the temperature effect caused by the structural temperature gradient of the wind tunnel balance.

[0003] Currently, there is an urgent need to develop a method for correcting the temperature effect caused by the temperature gradient of a wind tunnel balance. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for correcting the temperature effect caused by the temperature gradient of a wind tunnel balance, so as to overcome the defects of the prior art.

[0005] The temperature effect correction method for the temperature gradient of the wind tunnel balance of the present invention is based on a temperature detection device, a digital simulation system and a digital correction system. The temperature detection device includes a temperature sensor and a temperature signal detection system; the digital simulation system includes a three-dimensional digital model of the balance and finite element analysis software; the digital correction system includes a temperature signal correction program, a balance calibration formula, and aerodynamic load analysis software; The temperature effect correction method comprises the following steps: S10. Obtain the temperature distribution of the wind tunnel balance during the wind tunnel test; Arrange the temperature sensor at the position where the strain gauge is pasted; measure the temperature data {t1, t2, t3, t4, t5, ...} of the wind tunnel balance structure through the temperature sensor during the wind tunnel test; S20. Obtaining a mathematical model of wind tunnel balance temperature gradient distribution; The wind tunnel balance structure temperature data obtained from the wind tunnel test is converted into a temperature signal through a temperature signal detection system to obtain a mathematical model of the wind tunnel balance temperature gradient distribution {Δt1, Δt2, Δt3, Δt4, Δt5, ...}; S30. Obtaining the wind tunnel balance theoretical structural thermal strain and the wind tunnel balance theoretical bridge thermal output; A three-dimensional digital model of the wind tunnel balance structure was constructed, and the mathematical model of the temperature gradient distribution of the wind tunnel balance {Δt1, Δt2, Δt3, Δt4, Δt5, ...} was imported into the finite element analysis software. The theoretical structural thermal strain of each strain gauge pasting position of the wind tunnel balance and the theoretical bridge thermal output ΔUti of the wind tunnel balance were obtained by computer digital analysis, where i is the strain gauge bridge number corresponding to each component on the wind tunnel balance; S40. Obtaining a correction formula for temperature effect caused by temperature gradient; Through the digital correction system, the inverse solution is performed to obtain the theoretical heat output of the wind tunnel balance temperature gradient. Then, through the temperature signal correction program, the temperature data {t1, t2, t3, t4, t5, ...} of each characteristic point of the wind tunnel balance measured by the temperature sensor is corrected to obtain the correction formula as follows: ΔUi′=ΔUi-ΔUti; ΔUi′: Corrected measured voltage signal; ΔUi: original measured voltage signal; ΔUti: temperature gradient theoretical bridge heat input; S50. Obtaining corrected aerodynamic test data; The corrected wind tunnel balance measurement data is substituted into the wind tunnel balance calibration formula, and then the corrected aerodynamic test data is obtained through the aerodynamic load analysis software.

[0006] The temperature effect correction method caused by the temperature gradient of the wind tunnel balance of the present invention evaluates the structural deformation caused by the temperature gradient in the wind tunnel balance test and the resulting heat output of the measuring bridge through digital simulation, thereby correcting the temperature effect caused by the temperature gradient of the wind tunnel balance structure. It can effectively improve the quality of wind tunnel test data, especially for wind tunnel tests with large flow field temperature changes, and has engineering practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A flow chart of a method for correcting temperature effects caused by temperature gradients of a wind tunnel balance according to the present invention; Figure 2a Paste the layout diagram (front view) for the temperature sensor and strain gauge of a cryogenic balance; Figure 2b Paste the layout diagram (cross-section) of the temperature sensor and strain gauge of a cryogenic balance; Figure 3 This is the design diagram of the measuring bridge of a low-temperature balance; Figure 4 is the balance temperature gradient model of a low-temperature balance; Figure 5 is the stress distribution caused by the temperature gradient in the X direction of a cryogenic balance; A~H: section numbers of the wind tunnel balance; T01~T12: temperature sensor serial number; X1~X4: balance measurement bridge serial number; M1.1~M1.4: Strain gauge serial number of balance measurement bridge X1; M7.1~M7.4: Strain gauge serial number of balance measurement bridge X2; M8.1~M8.4: Strain gauge serial number of balance measurement bridge X3; M9.1~M9.4: Serial number of strain gauges of balance measuring bridge X4; R1: resistance number of balance measurement bridge X1; R7: resistance number of balance measurement bridge X2; R8: resistance number of balance measurement bridge X3; R9: resistance number of balance measurement bridge X4; Ve+: positive pole of power supply; Ve-: negative pole of power supply; Vd+: positive pole of power supply feedback; Vd-: negative pole of power supply feedback; Sense+: signal positive; Sense-: signal positive; PT100: Temperature sensor. DETAILED DESCRIPTION

[0008] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0009] Example: Figure 1 As shown, the temperature effect correction method caused by the temperature gradient of the wind tunnel balance in this embodiment is based on a temperature detection device, a digital simulation system and a digital correction system, wherein the temperature detection device includes a temperature sensor and a temperature signal detection system; the digital simulation system includes a three-dimensional digital model of the balance and finite element analysis software; the digital correction system includes a temperature signal correction program, a balance calibration formula, and aerodynamic load analysis software; The temperature effect correction method comprises the following steps: S10. Obtain the temperature distribution of the wind tunnel balance during the wind tunnel test; Arrange the temperature sensor at the position where the strain gauge is pasted; measure the temperature data {t1, t2, t3, t4, t5, ...} of the wind tunnel balance structure through the temperature sensor during the wind tunnel test; S20. Obtaining a mathematical model of wind tunnel balance temperature gradient distribution; The wind tunnel balance structure temperature data obtained from the wind tunnel test is converted into a temperature signal through a temperature signal detection system to obtain a mathematical model of the wind tunnel balance temperature gradient distribution {Δt1, Δt2, Δt3, Δt4, Δt5, ...}; S30. Obtaining the wind tunnel balance theoretical structural thermal strain and the wind tunnel balance theoretical bridge thermal output; A three-dimensional digital model of the wind tunnel balance structure was constructed, and the mathematical model of the temperature gradient distribution of the wind tunnel balance {Δt1, Δt2, Δt3, Δt4, Δt5, ...} was imported into the finite element analysis software. The theoretical structural thermal strain of each strain gauge pasting position of the wind tunnel balance and the theoretical bridge thermal output ΔUti of the wind tunnel balance were obtained by computer digital analysis, where i is the strain gauge bridge number corresponding to each component on the wind tunnel balance; S40. Obtaining a correction formula for temperature effect caused by temperature gradient; Through the digital correction system, the inverse solution is performed to obtain the theoretical heat output of the wind tunnel balance temperature gradient. Then, through the temperature signal correction program, the temperature data {t1, t2, t3, t4, t5, ...} of each characteristic point of the wind tunnel balance measured by the temperature sensor is corrected to obtain the correction formula as follows: ΔUi′=ΔUi-ΔUti; ΔUi′: Corrected measured voltage signal; ΔUi: original measured voltage signal; ΔUti: temperature gradient theoretical bridge heat input; S50. Obtaining corrected aerodynamic test data; The corrected wind tunnel balance measurement data is substituted into the wind tunnel balance calibration formula, and then the corrected aerodynamic test data is obtained through the aerodynamic load analysis software.

[0010] This embodiment analyzes and corrects the temperature effect caused by the temperature gradient of a certain low-temperature balance. Figure 2a , Figure 2b , the measuring bridge of a low temperature balance is shown in Figure 3 , the strain gauges form a Wheatstone bridge, which measures the output of the strain gauges.

[0011] The experiment heats the head of a low-temperature balance to form a temperature gradient in the balance structure. The balance temperature gradient model is obtained by reverse processing the temperature signal measured by the temperature sensor. Figure 4 The stress distribution caused by the temperature gradient in the X direction of the balance is shown in Figure 5 .

[0012] Table 1 shows the original measurement signal of the balance bridge of a certain cryogenic balance with temperature changes. The original measurement signal shows that the temperature change causes the original measurement signal of the balance to change, and the change is about 0.004 mV / V. Table 2 shows the numerical simulation results of thermal strain caused by the temperature gradient of a certain cryogenic balance. The numerical simulation results of thermal strain show that the structural temperature gradient caused by temperature change will cause the output of the balance bridge to change, and the change range is 0.002 mV / V to 0.003 mV / V, and the change trend is consistent with the change of the balance bridge signal. Table 3 shows the balance measurement signal after numerical correction of a certain cryogenic balance. The change of the corrected balance measurement signal has been greatly reduced, and the reduction is between 53% and 73%. The correction residual value is mainly caused by the change of the material properties of the balance strain gauge with temperature. It can be seen that the temperature effect correction method caused by the temperature gradient of the wind tunnel balance of the present invention has a good effect on the temperature effect caused by the temperature gradient of the balance structure.

[0013] Table 1

[0014] Table 2

[0015] Table 3

[0016] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes. For those familiar with the art, all features disclosed in the present invention, or steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for correcting the temperature effect caused by the temperature gradient of a wind tunnel balance, characterized in that: The temperature effect correction method is based on a temperature detection device, a digital simulation system and a digital correction system. The temperature detection device includes a temperature sensor and a temperature signal detection system; the digital simulation system includes a three-dimensional digital model of a balance and finite element analysis software; The digital correction system includes a temperature signal correction program, a balance calibration formula, and aerodynamic load analysis software; The temperature effect correction method comprises the following steps: S10. Obtain the temperature distribution of the wind tunnel balance during the wind tunnel test; Arrange the temperature sensor at the position where the strain gauge is pasted; measure the temperature data {t1, t2, t3, t4, t5, ...} of the wind tunnel balance structure through the temperature sensor during the wind tunnel test; S20. Obtaining a mathematical model of wind tunnel balance temperature gradient distribution; The wind tunnel balance structure temperature data obtained from the wind tunnel test is converted into a temperature signal through a temperature signal detection system to obtain a mathematical model of the wind tunnel balance temperature gradient distribution {Δt1, Δt2, Δt3, Δt4, Δt5, ...}; S30. Obtaining the wind tunnel balance theoretical structural thermal strain and the wind tunnel balance theoretical bridge thermal output; A three-dimensional digital model of the wind tunnel balance structure was constructed, and the mathematical model of the temperature gradient distribution of the wind tunnel balance {Δt1, Δt2, Δt3, Δt4, Δt5, ...} was imported into the finite element analysis software. The theoretical structural thermal strain of each strain gauge pasting position of the wind tunnel balance and the theoretical bridge thermal output ΔUti of the wind tunnel balance were obtained by computer digital analysis, where i is the strain gauge bridge number corresponding to each component on the wind tunnel balance; S40. Obtaining a correction formula for temperature effect caused by temperature gradient; Through the digital correction system, the inverse solution is performed to obtain the theoretical heat output of the wind tunnel balance temperature gradient. Then, through the temperature signal correction program, the temperature data {t1, t2, t3, t4, t5, ...} of each characteristic point of the wind tunnel balance measured by the temperature sensor is corrected to obtain the correction formula as follows: ΔUi′=ΔUi-ΔUti; ΔUi′: Corrected measured voltage signal; ΔUi: original measured voltage signal; ΔUti: temperature gradient theoretical bridge heat input; S50. Obtaining corrected aerodynamic test data; The corrected wind tunnel balance measurement data is substituted into the wind tunnel balance calibration formula, and then the corrected aerodynamic test data is obtained through the aerodynamic load analysis software.

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