A single-point reconstruction method for initial readings of balance in wind tunnel model rudder efficiency test

Abstract

The present invention discloses a single-point reconstruction method for the initial reading of a balance in a wind tunnel model rudder efficiency test. The method uses the current rudder deflection angle state as a reference to correct the initial reading before adjustment, thereby solving the initial reading zero-point drift caused by temperature changes in the balance strain gauge and data acquisition equipment, thereby quickly obtaining the initial reading applicable to the current rudder deflection angle state. Within the angle variation range, only one sample point needs to be collected to calculate the initial reading at the required angle, and the entire collection and processing process takes no more than 3 seconds. Compared with the traditional initial reading collection method, the single-point reconstruction method shortens the time by 360 seconds and improves the efficiency by 99%. The test result error introduced by the method is less than 0.00005, which meets the advanced index requirements of the low-speed wind tunnel force measurement test. At the same time, the evaluation criteria for the applicable scenarios of the method are designed to provide a guiding basis.

Description

Technical Field

[0001] The invention relates to the field of wind tunnel tests, and in particular to a single-point reconstruction method for initial readings of a balance in a wind tunnel model rudder effect test, which can be used for conventional wind tunnel aerodynamic tests of models of aircraft, vehicles and the like. Background Art

[0002] The wind tunnel model control surface efficiency test (also known as the rudder efficiency test) is to measure the size of the corresponding aerodynamic force generated by the unit deflection angle of various control surfaces (elevators, rudders, flaps, ailerons, etc.) under different flight conditions. The balance is the most commonly used equipment for measuring aerodynamic force in wind tunnel tests. It can decompose the aerodynamic force acting on the model into three mutually perpendicular forces and moments around three coordinate axes in the balance axis system, and obtain the size, direction and point of action of the aerodynamic force acting on the model through axis system conversion. When the wind tunnel has not yet blown, although there is no aerodynamic load on the model, the collected balance data is generally not zero, which is the so-called initial reading of the balance. This is because the weight of the model acts on the lift element of the balance on the one hand, and the center of gravity of the model generally does not coincide with the calibration center of the balance on the other hand. Therefore, when the model changes its attitude angle, the weight of the model will generate a moment that changes with the attitude angle. In wind tunnel tests, it is difficult to calculate these additional moments due to the many changes in the model's components and postures. Therefore, the initial reading of the balance can only be recorded through actual measurement. Subtracting the corresponding initial reading from the wind number in the later stage is the main method to eliminate the influence of the initial reading.

[0003] In the rudder effectiveness test, although the change of the model rudder angle does not cause a significant change in the model mass and center of gravity, there is usually a large difference in the initial readings before and after the rudder angle adjustment. This is because the airflow temperature changes during the blowing process, causing the electronic devices such as the balance and data acquisition equipment to drift due to the temperature. In order to ensure the accuracy of the rudder effectiveness test results, a complete initial reading must be collected before each blowing. The traditional way to collect the initial readings is:

[0004] Formulate an angle change sequence based on the change range and interval of the attitude angle ;

[0005] Adjust the model to the first angle point At this point, collect the current balance signal as the initial reading of the first point ;

[0006] Then adjust the model to the second angle point The initial reading is collected at the same time, and this is repeated until the entire angle sequence is collected. Initial reading of .

[0007] The disadvantage of traditional methods is that as the attitude angle range increases and the angle interval decreases, the time required to collect the initial readings also increases. Take the test as an example, when the angle of attack changes within the range of , , 91 acquisitions need to be completed, each acquisition takes 3 seconds, and the angle change rate is Therefore, it takes about 363 seconds to collect the initial readings before each blowing, which seriously restricts the improvement of test efficiency. Summary of the invention

[0008] The purpose of the present invention is to provide a single-point reconstruction method for the initial readings of the balance in a wind tunnel model rudder efficiency test, which does not require point-by-point collection of the initial readings of the balance under different postures within the entire angle range, avoids multiple adjustments to the model posture and multiple collections of initial readings, eliminates the influence of temperature zero-point drift, and shortens the time for collecting initial readings, thereby effectively improving the efficiency of the wind tunnel test.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] A single-point reconstruction method for the initial reading of a wind tunnel model rudder efficiency test balance includes two parts:

[0011] First, a criterion is constructed to evaluate the influence of the rudder deflection angle change of the wind tunnel model on the initial reading of the balance and determine the applicable field of the single-point reconstruction method, specifically:

[0012] Based on the advanced indicators of low-speed wind tunnel force test, the aerodynamic coefficients are converted into actual loads using dimensionless inverse operations to construct a threshold definition. :

[0013]

[0014] in is the weight, and its value range is ; is the inverse operation; Represents the six components of the balance (three force components , , and the three torque components , , ).

[0015] The changes in the model mass and center of gravity caused by the change in rudder angle are calculated :

[0016]

[0017] In the formula and They are the changes of force and moment caused on the balance axis system before and after the model rudder deflection angle is adjusted.

[0018] use and Constructing the judging criteria:

[0019] when When the balance change caused by the change of the rudder angle is ignored, the initial balance reading under the current rudder angle state is quickly generated using the single-point reconstruction method;

[0020] when When the balance change caused by the change of rudder angle cannot be ignored, use single point-by-point collection of initial readings;

[0021] In the formula is an absolute value operation. When , it shows that the change of the model rudder angle does not cause a significant change in the model mass and center of gravity, and the single-point reconstruction method can be used to quickly generate the initial balance reading under the current rudder angle state; When the instrument is in operation, the initial readings are collected point by point using the traditional method.

[0022] Second, in the application scenario that meets the evaluation criteria, the initial reading before adjustment is corrected based on the adjusted rudder angle state to eliminate the influence of temperature zero drift on the balance, so as to quickly obtain the initial reading suitable for the current rudder angle state, specifically:

[0023] When conducting a rudder efficiency test on a specific component, first use the point-by-point acquisition mode to collect a line with The initial readings of discrete points are used as reference initial readings , Represents different discrete angles .

[0024] Adjust the model to a specific angle when changing the rudder angle of that specific part back, , collect an initial reading as the reference single point initial reading .

[0025] Initial reading of reference Perform polynomial interpolation to obtain the value of each component of the balance Reference initial reading at :

[0026] ,

[0027] In the formula For the angle Balance The reference initial reading corresponding to the component.

[0028] Calculate the angle of each component of the balance Initial reading deviation :

[0029]

[0030] At every angle Initial reading of reference The six balance components in the rudder are corrected one by one to obtain the initial reconstructed reading of the current rudder deflection state. :

[0031]

[0032] Single point reconstruction initial reading With reference initial reading The same change trend and angle range accurately describe the model at different posture angles The changing rules of each weight of the lower balance; Initial reading with reference point Having the same bias reference corrects the effect of temperature zero drift.

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

[0034] The present invention only needs to collect data points at one angle to quickly deduce the test angle. For other unknown data points within the range, the influence of temperature zero drift on the initial reading is corrected by interpolation and difference method, which is suitable for application scenarios with small model layout adjustment such as rudder angle change. The entire acquisition and processing time of the single-point reconstruction method is no more than 3 seconds, which is 360 seconds shorter than the traditional initial reading acquisition method, and the efficiency is improved by 99%. The test result error is less than 0.00005, which meets the advanced index requirements of low-speed wind tunnel force measurement test. At the same time, the evaluation criteria for the applicable scenarios of this method are designed to provide guidance for the efficient implementation of rudder efficiency tests of different components of wind tunnel models. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0036] Figure 1 Single-point reconstruction process for initial reading of balance for wind tunnel model rudder efficiency test;

[0037] Figure 2 This is the error comparison diagram of the three force components of this method;

[0038] Figure 3 It is the error comparison diagram of the three torque components of this method;

[0039] Figure 4 This is a comparison chart of the errors of temperature zero drift on the three force components;

[0040] Figure 5 This is a comparison chart of the errors of temperature zero drift on the three torque components. DETAILED DESCRIPTION

[0041] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0042] Any feature disclosed in this specification (including any additional claims, abstract and drawings), unless otherwise stated, may be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0043] The specific process of this embodiment is as follows Figure 1 As shown, specifically:

[0044] Step 1: According to the low-speed wind tunnel force test accuracy indicators as shown in the table below, model parameters and test conditions, the advanced indicators of the six aerodynamic components are , Represents the six components of the balance (three force components , , and the three torque components , , ), converted to the corresponding threshold :

[0045]

[0046] ,

[0047] ,

[0048] ,

[0049] ,

[0050] ,

[0051] ,

[0052] in For speed pressure, is the reference area, is the wing span, is the average aerodynamic chord length of the wing, these four parameters are known quantities; is the weight, and its value range is ; , , , , They are the advanced indicators of the six aerodynamic components in low-speed wind tunnel tests. or , big side slide or , currently no accuracy indicators for force measurement test data are specified.

[0053] The reference area of ​​a model in this example , Wingspan , average aerodynamic chord length of the wing ; Speed ​​pressure ; Weight . Define the threshold The specific values ​​are as follows:

[0054]

[0055] Step 2: Calculate the change in model mass and center of gravity caused by the change in rudder angle :

[0056]

[0057] In the formula and They are the changes of force and moment caused on the balance axis system before and after the model rudder deflection angle is adjusted.

[0058] In this example, when the model flap is Adjust to When The changes are shown in the following table:

[0059]

[0060] Step 3: Compare and , evaluate the size of the model rudder angle adjustment: when When , it indicates that the change in the balance caused by the change in the rudder angle can be ignored; and when This indicates that the change in the balance caused by the change in the rudder angle cannot be ignored.

[0061] In this example, the comparison and It can be seen that the change of each component satisfies , indicating that the flap is Adjust to The change in the balance caused by this can be ignored.

[0062] Step 4: When a rudder part of the model is installed for the first time, According to the test requirements, the traditional initial reading acquisition method is used to collect the angle sequence. Internal point-by-point acquisition Discrete data as a reference initial reading In this example, flaps are selected The initial reading is used as a reference initial reading , The range is .

[0063] Step 5: When the rudder part of the model is adjusted to install the deflection angle, At this time Select any position within the angle range as the reference angle ;exist Collect a data point as the initial reading of the reference point The base angle selected in this example is .

[0064] Step 6: Take an initial reading of the reference The data is processed by polynomial interpolation to obtain the value of each component of the balance. Reference initial reading at :

[0065]

[0066] The purpose of interpolation is to avoid situation, ensure and At the same angle Down.

[0067] Step 7: Calculate the angle of each component of the balance Initial reading deviation .

[0068] Step 8: At each angle Initial reading of reference The six balance components in the rudder are corrected one by one to obtain the initial reconstructed reading of the current rudder deflection state. . Reconstructing the initial reading The angular range is still ,and , the temperature drift zero drift is corrected.

[0069] Model flap and Take the initial reading of as an example:

[0070] In the traditional data collection method, the initial readings actually obtained, although the model rudder angle adjustment amount can be ignored, but due to the influence of temperature zero drift, the actual flap and The maximum change in the initial reading exceeds the accuracy of the low-speed wind tunnel force test, such as Figure 4 and Figure 5 So you can't just The initial reading is used for The initial reading of , To obtain the initial reading, 50 acquisitions need to be completed, which takes at least 199 seconds, and the test efficiency is low.

[0071] When the model flap is adjusted to When Collect a reference initial reading ; Then select the existing Initial reading as a reference initial reading , and make an initial reading of the reference Make corrections to obtain The reconstruction of the initial reading , the whole process takes no more than 3 seconds. Figure 2 and Figure 3 As shown in the figure, it can be seen that the maximum error between the two is less than the advanced index requirements of low-speed wind tunnel force test. The use of single-point reconstruction method not only ensures the reliability of the test results, but also greatly improves the test efficiency.

[0072] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A single-point reconstruction method for initial readings of a balance in a wind tunnel model rudder efficiency test, characterized in that It consists of two parts: S1: Construct a criterion to evaluate the effect of the rudder deflection angle change of the wind tunnel model on the initial reading of the balance and determine the applicable field of the single-point reconstruction method; S11: Based on the advanced indicators of wind tunnel force test, the aerodynamic coefficients are converted into actual loads by using dimensionless inverse operation to construct the defined thresholds; S12: Obtaining the load change before and after the model layout is adjusted due to the change in the rudder deflection angle by calculation; S13: Use the defined threshold and load change to construct the evaluation criteria as follows: when When the balance change caused by the change of the rudder angle is ignored, the initial balance reading under the current rudder angle state is quickly generated using the single-point reconstruction method; when When the balance change caused by the change of rudder angle cannot be ignored, use single point-by-point collection of initial readings; in: is the load variation, To define the threshold, is the absolute value operation; S2: In the application scenario that meets the evaluation criteria, the initial reading before adjustment is corrected based on the adjusted rudder angle state, eliminating the influence of temperature zero drift on the balance, and quickly obtaining the initial reading applicable to the current rudder angle state; S21: using the point-by-point acquisition mode to acquire a preliminary reading with a plurality of discrete points as a reference preliminary reading; S22: When changing the rudder deflection angle, after adjusting the model to any angle, collect an initial reading as the reference single point initial reading; S23: Perform polynomial interpolation processing on the reference initial reading to obtain the reference initial reading of each component of the balance at the angle adjusted in S22; S24: Obtaining the initial reading deviation of each component of the balance at the angle adjusted in S22 by calculation; S25: Correct the six balance components in the reference initial reading one by one at each angle to obtain a reconstructed initial reading of the current rudder deflection angle state.

2. The single-point reconstruction method of the initial reading of the balance in the wind tunnel model rudder efficiency test according to claim 1 is characterized in that: The defined threshold is: , The load variation is: , Among them: is the weight, and its value range is ; is the inverse operation; Represents the six components of the balance, is the load after the model rudder deflection angle is adjusted, is the load before the model rudder deflection angle is adjusted.

3. The single-point reconstruction method of the initial reading of the balance in the wind tunnel model rudder efficiency test according to claim 1 is characterized in that: The reference initial reading of each component of the balance at the adjustment angle is: ， The reconstructed initial reading is: , in: To adjust the angle, For each weight on the balance The reference initial reading at , and is a natural number representing the number of different discrete angles, For the angle Balance The reference initial reading corresponding to the component, This is the initial reading of the benchmark single point.

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