Wind tunnel balance formula model and aerodynamic measurement method considering temperature effect

Abstract

The present invention discloses a wind tunnel balance formula model and a method for measuring aerodynamic forces that considers the influence of temperature effects, belonging to the field of static calibration of wind tunnel balances. Based on the traditional implicit balance formula, the present invention adds a temperature effect compensation function to the principal term coefficient and output voltage increment, forming a new balance formula model with temperature effect compensation. The balance formula model uses the balance's temperature data to modify the original balance formula, effectively reducing the impact of temperature effects on balance measurements and improving balance measurement accuracy. The model has a wide range of applications in the field of static calibration of wind tunnel balances.

Description

Technical Field

[0001] The invention relates to a wind tunnel balance formula model and an aerodynamic force measurement method considering the influence of temperature effect, and belongs to the field of wind tunnel balance static calibration. Background Art

[0002] The balance formula is a relationship between the balance output voltage and the load, constructed through static calibration. It's typically a polynomial function, solved using linear fitting methods such as the least squares method. Based on the dependent and explanatory variables of the polynomial function, balance formulas can be divided into explicit and implicit balance formulas. The dependent variable of an explicit balance formula is the load value of each component, and the explanatory variable is the output voltage increment of each component. The dependent variable of an implicit balance formula is the load value of each component, and the explanatory variables are the output voltage increment of that component and the load value of each component.

[0003] Typically, the balance formula is determined after static calibration and is used to calculate the load on the balance. However, in wind tunnel experiments, if the test duration is long, high-temperature, high-pressure air flows through the internal flow field, or if the jet drop pressure ratio is simulated, the heat from the flow field can be transferred to the balance through heat conduction and other methods, causing significant temperature changes and generating a temperature effect. This temperature effect can significantly affect the coefficients of the balance formula and the balance zero-point voltage, resulting in large errors in the calculated load, seriously affecting the credibility and usability of the experimental data. Summary of the Invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the existing technology, propose a wind tunnel balance formula model and a method for measuring aerodynamic force that takes into account the influence of temperature effect, use the temperature data of the wind tunnel balance to correct the traditional implicit balance formula, effectively reduce the influence of temperature effect on wind tunnel balance measurement, and realize accurate measurement of aerodynamic force.

[0005] The technical solution of the present invention is:

[0006] A wind tunnel balance formula model considering the influence of temperature effect is as follows:

[0007]

[0008] Where U i is the voltage output value of the i-th component, f0(T) is the steady-state zero drift compensation function, f s (T) is the steady-state sensitivity drift compensation function, f g (T) is the dynamic temperature gradient compensation function; F i is the load value of the i-th component of the balance, T is the balance temperature; α i is the intercept term, a i is the main term coefficient, is the first-order interference correction coefficient of the j-th component load on the i-th component, is the second-order square interference correction coefficient and cross-term interference correction coefficient of each component load on the i-th component.

[0009] Furthermore, considering the temperature effect, the steady-state zero drift compensation function f0(T) corrects the output voltage to compensate for the steady-state zero drift; the steady-state sensitivity drift compensation function f s (T) Correct the main coefficient to compensate for the steady-state sensitivity drift; the dynamic temperature gradient affects the compensation function f g (T) Correct the output voltage increment to compensate for the impact of dynamic temperature gradients.

[0010] Furthermore, a steady-state zero drift compensation function is constructed, that is, a curve showing the change of the zero voltage value of the balance with temperature in the steady state is obtained. The specific method is as follows:

[0011] Multiple steady-state temperature collection points are designed, and the zero-point voltage value of the balance is measured at each collection point. According to the obtained temperature at each point and the corresponding zero-point voltage value, a steady-state zero-point drift compensation function is established through linear regression.

[0012] Furthermore, a steady-state sensitivity drift compensation function is constructed, that is, a curve showing the main coefficient compensation value changing with temperature is obtained. The specific method is as follows:

[0013] Multiple steady-state temperature collection points are designed. At each collection point, a load is applied to the balance. The output voltage increment of the balance is measured, and the load is back-calculated based on the implicit balance formula and the output voltage increment. A compensation value is then added after the principal coefficient so that the error between the back-calculated load and the applied load is within 1%. The temperature of each collection point and the corresponding principal coefficient compensation value are recorded, and a steady-state sensitivity drift compensation function is constructed through linear regression.

[0014] Furthermore, the implicit balance formula is:

[0015]

[0016] Where, ΔU i is the output voltage increment of the i-th component of the balance.

[0017] Furthermore, a dynamic temperature gradient compensation function is constructed, that is, a curve showing the dynamic change of the zero-point voltage value of the balance with temperature is obtained. The specific method is as follows:

[0018] Design the temperature change range and record the zero-point voltage value of the balance during the temperature change process;

[0019] According to the constructed steady-state zero drift compensation function, the zero point voltage value change caused by the steady-state zero drift is removed, and the remaining is the zero point voltage value change caused by the dynamic temperature gradient;

[0020] Record each temperature point and the corresponding zero-point voltage change caused by the dynamic temperature gradient, and construct a dynamic temperature gradient compensation function through linear regression.

[0021] The method of measuring aerodynamic forces using a wind tunnel balance formula model that takes into account the temperature effect includes:

[0022] Step 1: Complete the static calibration of the wind tunnel balance and obtain the implicit balance formula;

[0023] Step 2: Place the model to be tested in a wind tunnel and conduct a wind tunnel test. Use a wind tunnel balance to measure the aerodynamic forces acting on the model.

[0024] Step 3: During the test, design multiple steady-state temperature collection points and measure the zero-point voltage value of the balance at each collection point. Based on the obtained temperature at each point and the corresponding zero-point voltage value, establish a steady-state zero-point drift compensation function through linear regression.

[0025] Step 4: During the test, design multiple steady-state temperature collection points. At each collection point, apply a load to the balance, measure the output voltage increment of the balance, and back-calculate the load based on the implicit balance formula and the output voltage increment. Then, add a compensation value after the principal coefficient so that the error between the back-calculated load and the applied load is within 1%. Record the temperature of each collection point and the corresponding principal coefficient compensation value, and construct a steady-state sensitivity drift compensation function through linear regression.

[0026] Step 5: During the test, design a temperature variation range and record the zero voltage value of the balance during the temperature variation process. Based on the constructed steady-state zero drift compensation function, remove the zero voltage value change caused by the steady-state zero drift, and the remaining zero voltage value change caused by the dynamic temperature gradient is recorded at each temperature point and the corresponding zero voltage value change caused by the dynamic temperature gradient. The dynamic temperature gradient compensation function is constructed through linear regression.

[0027] Step 6: Based on the implicit balance formula, the constructed steady-state zero drift compensation function, steady-state sensitivity drift compensation function, and dynamic temperature gradient influence compensation function are substituted into the wind tunnel balance formula model to obtain aerodynamic data.

[0028] Furthermore, the implicit balance formula is:

[0029]

[0030] Where ΔU iis the output voltage increment of the i-th component of the balance, F i is the load value of the i-th component of the balance, T is the balance temperature; α i is the intercept term, a i is the main term coefficient, is the first-order interference correction coefficient of the j-th component load on the i-th component, is the second-order square interference correction coefficient and cross-term interference correction coefficient of each component load on the i-th component.

[0031] The advantages of the present invention compared with the prior art are:

[0032] The wind tunnel balance formula model designed in this invention compensates for the steady-state zero drift, steady-state sensitivity drift, and dynamic temperature gradient effects caused by temperature effects by constructing steady-state zero drift compensation functions, steady-state sensitivity drift compensation functions, and dynamic temperature gradient effect compensation functions. The steady-state zero drift compensation function corrects the output voltage to compensate for steady-state zero drift; the steady-state sensitivity drift compensation function corrects the main term coefficient to compensate for steady-state sensitivity drift; and the dynamic temperature gradient effect compensation function corrects the output voltage increment to compensate for the dynamic temperature gradient effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0034] Figure 1 This is a flow chart of a method for measuring aerodynamic force using a wind tunnel balance formula model according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0036] The present invention proposes a wind tunnel balance formula model that takes temperature effects into account. Compared with the traditional implicit balance formula, it can compensate for three temperature effects: steady-state zero drift, steady-state sensitivity drift and dynamic temperature gradient influence.

[0037] The traditional balance formula is a 6×27-term implicit balance formula:

[0038]

[0039] Where, F i is the load value of the i-th component of the balance, ΔU i is the output voltage increment of the i-th component of the balance, α i is the intercept term, a i is the main term coefficient, is the first-order interference correction coefficient of other component loads on the i-th component, is the second-order square interference correction coefficient and cross-term interference correction coefficient of each component load on the i-th component.

[0040] The present invention modifies the implicit balance formula to form a wind tunnel balance formula model:

[0041]

[0042] Where U i is the voltage output value of the i-th component, f0(T) is the steady-state zero drift compensation function, f s (T) is the steady-state sensitivity drift compensation function, f g (T) is the dynamic temperature gradient compensation function.

[0043] The steady-state zero drift compensation function f0(T) corrects the output voltage increment to compensate for the steady-state zero drift.

[0044] Steady-state sensitivity drift compensation function f s (T) Correct the main coefficient to compensate for the steady-state sensitivity drift.

[0045] Dynamic temperature gradient impact compensation function f g (T) Correct the output voltage increment to compensate for the impact of dynamic temperature gradients.

[0046] The aerodynamic force measurement method using the wind tunnel balance formula model is as follows Figure 1 Shown, including:

[0047] Step 1: Complete static calibration of the wind tunnel balance to obtain the implicit balance formula. This static calibration is performed on a balance calibration stand. Refer to the "GJB2244A-2011 Wind Tunnel Strain Balance Specification" to obtain the implicit balance formula. The following temperature compensation calibration is performed in a high and low temperature test chamber.

[0048] Step 2: Place the model to be tested in a wind tunnel and conduct a wind tunnel test. Use a wind tunnel balance to measure the aerodynamic forces acting on the model.

[0049] Step 3: Construct a steady-state zero drift compensation function, which is a curve showing how the balance's zero voltage changes with temperature in the steady state. Design multiple steady-state temperature acquisition points and measure the balance's zero voltage at each acquisition point. Because temperature effects can cause differences in zero voltage at different temperatures, construct a steady-state zero drift compensation function using methods such as linear regression.

[0050] Step 4: Construct a steady-state sensitivity drift compensation function, which is a curve showing how the principal coefficient compensation value changes with temperature. Design multiple steady-state temperature acquisition points. Apply a load to the balance at each acquisition point, measure the balance output voltage increment, and reverse-calculate the load based on the original balance formula and the output voltage increment. Due to temperature effects, the reverse-calculated load will have a large error. Then, add a compensation value after the principal coefficient to ensure that the reverse-calculated load is close to the applied load. Record the principal coefficient compensation value at each acquisition point. Finally, construct a steady-state sensitivity drift compensation function using methods such as linear regression.

[0051] Step 5: Construct a dynamic temperature gradient compensation function, i.e., a curve showing the dynamic temperature gradient variation of the balance zero voltage. Design a temperature range and record the balance zero voltage during these temperature variations. Due to the temperature effect, the balance zero voltage will vary with temperature. Then, using the steady-state zero drift compensation function constructed in Step 2, remove the zero voltage variation caused by steady-state zero drift, leaving only the zero voltage variation caused by the dynamic temperature gradient. Finally, construct a dynamic temperature gradient compensation function using linear regression, artificial intelligence algorithms, and other methods.

[0052] Step 6: Substitute the constructed steady-state zero drift compensation function, steady-state sensitivity drift compensation function, and dynamic temperature gradient influence compensation function into the balance formula to obtain a balance formula model that can compensate for the temperature effect. Measure the aerodynamic force and aerodynamic torque acting on the model for subsequent model selection, model aerodynamic control design, and verification.

[0053] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for establishing a wind tunnel balance formula model considering the influence of temperature effect, characterized in that: The wind tunnel balance formula model is: Where U i is the voltage output value of the i-th component, f0(T) is the steady-state zero drift compensation function, f s (T) is the steady-state sensitivity drift compensation function, f g (T) is the dynamic temperature gradient compensation function; F i is the load value of the i-th component of the balance, T is the balance temperature; α i is the intercept term, a i is the main term coefficient, is the first-order interference correction coefficient of the j-th component load on the i-th component, is the second-order square interference correction coefficient and cross-term interference correction coefficient of each component load on the i-th component.

2. The method for establishing a wind tunnel balance formula model considering the temperature effect according to claim 1 is characterized in that: Taking the temperature effect into consideration, the steady-state zero drift compensation function f0(T) corrects the output voltage to compensate for the steady-state zero drift; the steady-state sensitivity drift compensation function f s (T) Correct the main coefficient to compensate for the steady-state sensitivity drift; the dynamic temperature gradient affects the compensation function f g (T) Correct the output voltage increment to compensate for the impact of dynamic temperature gradients.

3. The method for establishing a wind tunnel balance formula model considering the temperature effect according to claim 1 or 2, characterized in that: Construct a steady-state zero drift compensation function, that is, obtain a curve showing the change of the zero voltage value of the balance with temperature in the steady state. The specific method is as follows: Multiple steady-state temperature collection points are designed, and the zero-point voltage value of the balance is measured at each collection point. According to the obtained temperature at each point and the corresponding zero-point voltage value, a steady-state zero-point drift compensation function is established through linear regression.

4. The method for establishing a wind tunnel balance formula model considering the temperature effect according to claim 1 or 2, characterized in that: Construct a steady-state sensitivity drift compensation function, that is, obtain a curve showing the main coefficient compensation value changing with temperature. The specific method is as follows: Design multiple steady-state temperature collection points, apply a load to the balance at each collection point, measure the output voltage increment of the balance, and inversely calculate the load based on the implicit balance formula and the output voltage increment; Then, a compensation value is added after the main coefficient so that the error between the inversely calculated load and the applied load is within 1%. The temperature of each acquisition point and the corresponding main coefficient compensation value are recorded, and a steady-state sensitivity drift compensation function is constructed by linear regression.

5. The method for establishing a wind tunnel balance formula model considering the temperature effect according to claim 4 is characterized in that: The implicit balance formula is: Where, ΔU i is the output voltage increment of the i-th component of the balance.

6. The method for establishing a wind tunnel balance formula model considering temperature effects according to claim 3, characterized in that: Construct a dynamic temperature gradient compensation function, that is, obtain the curve of the balance zero point voltage value changing with temperature under dynamic conditions. The specific method is as follows: Design the temperature change range and record the zero-point voltage value of the balance during the temperature change process; According to the constructed steady-state zero drift compensation function, the zero point voltage value change caused by the steady-state zero drift is removed, and the remaining is the zero point voltage value change caused by the dynamic temperature gradient; Record each temperature point and the corresponding zero-point voltage change caused by the dynamic temperature gradient, and construct a dynamic temperature gradient compensation function through linear regression.

7. The method for measuring aerodynamic force using the wind tunnel balance formula model considering the temperature effect as described in claim 1 is characterized in that: include: Step 1: Complete the static calibration of the wind tunnel balance and obtain the implicit balance formula; Step 2: Place the model to be tested in a wind tunnel and conduct a wind tunnel test. Use a wind tunnel balance to measure the aerodynamic forces acting on the model. Step 3: During the test, design multiple steady-state temperature collection points and measure the zero-point voltage value of the balance at each collection point; According to the obtained temperature of each point and the corresponding zero-point voltage value, a steady-state zero-point drift compensation function is established through linear regression; Step 4: During the test, design multiple steady-state temperature collection points, apply a load to the balance at each collection point, measure the output voltage increment of the balance, and inversely calculate the load based on the implicit balance formula and the output voltage increment; Then, a compensation value is added after the main coefficient so that the error between the inversely calculated load and the applied load is within 1%. The temperature of each acquisition point and the corresponding main coefficient compensation value are recorded, and a steady-state sensitivity drift compensation function is constructed through linear regression. Step 5: During the test, design the temperature change range and record the zero-point voltage value of the balance during the temperature change process; According to the constructed steady-state zero drift compensation function, the zero point voltage value change caused by the steady-state zero drift is removed, and the remaining is the zero point voltage value change caused by the dynamic temperature gradient. Each temperature point and the corresponding zero point voltage value change caused by the dynamic temperature gradient are recorded, and the dynamic temperature gradient influence compensation function is constructed by linear regression. Step 6: Based on the implicit balance formula, the constructed steady-state zero drift compensation function, steady-state sensitivity drift compensation function, and dynamic temperature gradient influence compensation function are substituted into the wind tunnel balance formula model to obtain the aerodynamic data acting on the model.

8. The method for measuring aerodynamic force according to claim 7, characterized in that: The implicit balance formula is: Where, ΔU i is the output voltage increment of the i-th component of the balance, F i is the load value of the i-th component of the balance, T is the balance temperature; α i is the intercept term, a i is the main term coefficient, is the first-order interference correction coefficient of the j-th component load on the i-th component, is the second-order square interference correction coefficient and cross-term interference correction coefficient of each component load on the i-th component.

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