Wind tunnel balance formula model considering temperature effect influence and aerodynamic force measuring method

Abstract

The invention discloses a wind tunnel balance formula model considering temperature effect influence and a method for measuring aerodynamic force, and belongs to the field of static calibration of wind tunnel balances. On the basis of a traditional implicit balance formula, a temperature effect compensation function is added to a main item coefficient and an output voltage increment, and a new balance formula model with a temperature effect compensation function is formed. According to the balance formula model, the original balance formula is corrected by using the temperature data of the balance, the influence of the temperature effect on balance measurement is effectively reduced, the measurement accuracy of the balance is improved, and the method has a wide application scene in the field of static calibration of the wind tunnel balance.

Description

Technical Field

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

[0002] The balance formula is the relationship between the balance output voltage and the load constructed by static calibration. It is usually a polynomial function and is solved by linear fitting methods such as the least squares method. According to the dependent variable and explanatory variable of the polynomial function, the balance formula can be divided into two categories: explicit balance formula and implicit balance formula. The dependent variable of the 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 the implicit balance formula is the load value of each component, and the explanatory variable is the output voltage increment of the component and the load value of each component.

[0003] Normally, the balance formula can be determined after static calibration and is used to calculate the load on the balance. However, in wind tunnel experiments, if the experiment lasts for a long time, high-temperature and high-pressure air flows through the internal flow field, and the jet drop pressure ratio is simulated, the heat of the flow field will be transferred to the balance through heat conduction and other means, causing the balance temperature to change significantly, resulting in a temperature effect. The temperature effect will greatly affect the coefficient of the balance formula and the zero-point voltage value of the balance, resulting in a large error in the calculated load, which seriously affects the credibility and availability of the experimental data. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to propose a wind tunnel balance formula model and a method for measuring aerodynamic force that considers the influence of temperature effect, to use the temperature data of the wind tunnel balance to correct the traditional implicit balance formula, to effectively reduce the influence of temperature effect on wind tunnel balance measurement, and to achieve 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, the wind tunnel balance formula model is:

[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 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 gradient.

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

[0011] 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.

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

[0013] 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 backcalculate the load according to the implicit balance formula and the output voltage increment. Then add a compensation value after the principal coefficient so that the error between the backcalculated 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.

[0014] Furthermore, the implicit balance formula is:

[0015]

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

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

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

[0019] According to the constructed steady-state zero drift compensation function, the zero voltage value change caused by the steady-state zero drift is removed, and the remaining is the zero 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 impact compensation function through linear regression.

[0021] The method of measuring aerodynamic force using a wind tunnel balance formula model taking 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, conduct a wind tunnel test, and measure the aerodynamic force acting on the model using a wind tunnel balance;

[0024] Step 3: During the test, multiple steady-state temperature collection points are designed, and the zero-point voltage value of the balance is measured at each collection point; based on the obtained temperature at each point and the corresponding zero-point voltage value, a steady-state zero-point drift compensation function is established by linear regression;

[0025] Step 4: During the test, multiple steady-state temperature collection points are designed, and a load is applied to the balance at each collection point. The output voltage increment of the balance is measured, and the load is back-calculated according to the implicit balance formula and the output voltage increment. Then, a compensation value is 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 by linear regression.

[0026] Step 5: During the test, design the temperature change range and record the zero voltage value of the balance during the temperature change process; according to the constructed steady-state zero drift compensation function, remove the zero voltage value change caused by the steady-state zero drift, and the remaining is the zero voltage value change caused by the dynamic temperature gradient; record each temperature point and the corresponding zero voltage value change caused by the dynamic temperature gradient, and construct the dynamic temperature gradient influence compensation function by 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 the aerodynamic data.

[0028] Furthermore, the implicit balance formula is:

[0029]

[0030] In the formula, 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 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 by the present invention compensates for the steady-state zero drift, steady-state sensitivity drift and dynamic temperature gradient effect caused by the temperature effect by constructing a steady-state zero drift compensation function, a steady-state sensitivity drift compensation function and a dynamic temperature gradient effect compensation function. Among them, the steady-state zero drift compensation function corrects the output voltage to compensate for the steady-state zero drift; the steady-state sensitivity drift compensation function corrects the main term coefficient to compensate for the steady-state sensitivity drift; 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 of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying 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] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the 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. On the contrary, 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 which takes temperature effect into consideration. Compared with the traditional implicit balance formula, it can compensate for three temperature effects, namely 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] In the formula, 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 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, and the wind tunnel balance formula model formed is:

[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 coefficients to compensate for 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 gradient.

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

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

[0048] Step 2: Place the model to be tested in a wind tunnel, conduct a wind tunnel test, and measure the aerodynamic force acting on the model using a wind tunnel balance;

[0049] Step 3: Construct a steady-state zero drift compensation function, that is, a curve showing the change of the zero voltage value of the balance with temperature in the steady state. Design multiple steady-state temperature collection points, and measure the zero voltage value of the balance at each collection point. Due to the influence of the temperature effect, the zero voltage value at different temperatures will be different. Finally, a steady-state zero drift compensation function is constructed by linear regression and other methods.

[0050] Step 4: Construct a steady-state sensitivity drift compensation function, that is, a curve showing the change of the compensation value of the main coefficient with temperature. Design multiple steady-state temperature acquisition points, apply a load to the balance at each acquisition point, measure the output voltage increment of the balance, and reversely calculate the load based on the original balance formula and the output voltage increment. Due to the influence of the temperature effect, the reversely calculated load will have a large error. Then add a compensation value after the main coefficient so that the reversely calculated load is close to the applied load, record the main coefficient compensation value at each acquisition point, and finally construct a steady-state sensitivity drift compensation function through linear regression and other methods.

[0051] Step 5: Construct a dynamic temperature gradient effect compensation function, that is, a curve showing the dynamic change of the zero voltage value of the balance with temperature. Design the temperature change range and record the zero voltage value of the balance during the temperature change process. Due to the influence of the temperature effect, the zero voltage value of the balance will change with the temperature change. Then, according to the steady-state zero drift compensation function constructed in step 2, 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 left. Finally, a dynamic temperature gradient effect compensation function is constructed by linear regression, artificial intelligence algorithm, etc.

[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, etc.

[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 wind tunnel balance formula model considering the 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 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 wind tunnel balance formula model considering the temperature effect according to claim 1 is characterized in that: 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 gradient.

3. The 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 the curve of the balance zero voltage value changing with temperature in the steady state. The specific method is: 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.

4. The 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 the curve of the main coefficient compensation value changing with temperature. The specific method is: Design multiple steady-state temperature collection points, apply load to the balance at each collection point, measure the output voltage increment of the balance, and reversely calculate the load based on the implicit balance formula and the output voltage increment; Then, a compensation value is 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 acquisition point and the corresponding principal coefficient compensation value are recorded, and a steady-state sensitivity drift compensation function is constructed by linear regression.

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

6. The wind tunnel balance formula model considering the temperature effect according to claim 3 is characterized in that: Construct a dynamic temperature gradient influence compensation function, that is, obtain the curve of the dynamic balance zero point voltage value changing with temperature. The specific method is: Design the temperature change range and record the zero voltage value of the balance during the temperature change process; According to the constructed steady-state zero drift compensation function, the zero voltage value change caused by the steady-state zero drift is removed, and the remaining is the zero 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 impact 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, conduct a wind tunnel test, and measure the aerodynamic force acting on the model using a wind tunnel balance; 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 by linear regression; Step 4: During the test, multiple steady-state temperature collection points are designed, a load is applied to the balance at each collection point, the output voltage increment of the balance is measured, and the load is calculated based on the implicit balance formula and the output voltage increment; Then, a compensation value is 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 acquisition point and the corresponding principal coefficient compensation value are recorded, and a steady-state sensitivity drift compensation function is constructed by linear regression. Step 5: During the test, design the temperature change range and record the zero voltage value of the balance during the temperature change process; According to the constructed steady-state zero drift compensation function, the zero voltage value change caused by the steady-state zero drift is removed, and the remaining is the zero voltage value change caused by the dynamic temperature gradient; each temperature point and the corresponding zero 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: In the formula, 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 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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