A real-time attitude and velocity pressure calculation method for a wind tunnel free flight test model

Abstract

A method for solving the real-time attitude and speed pressure of a wind tunnel free flight test model belongs to the field of aerodynamics and wind tunnel testing. To solve the problems of insufficient anti-interference ability and low precision of the prior art, the present invention adopts a three-point method, arranges three pressure measuring points on the surface of the model, obtains pressure values ​​through wind tunnel pressure test, and uses a solving algorithm to obtain the model attitude and speed pressure. This method is real-time and does not require the introduction of external measuring equipment on the fuselage surface, completely avoiding the influence of changes in aerodynamic shape on the accuracy of attitude angle and speed pressure measurement, and constructs a low-interference, refined model attitude and speed pressure solving method that meets the needs of wind tunnel free flight tests of small aspect ratio flying wing layouts. Compared with traditional solving methods, this method avoids the decrease in measurement accuracy as the attitude increases, meets the needs of small aspect ratio flying wing layouts for accurate measurement of attitude data due to strong nonlinear characteristics, and improves the reliability of wind tunnel free flight test data of this layout.

Description

Technical Field

[0001] The invention relates to the field of aerodynamics and wind tunnel tests, and in particular to a real-time attitude and speed-pressure solution method for a small aspect ratio flying wing layout wind tunnel free flight test model. Background Art

[0002] As an important platform for the development of a new generation of fighter jets, the low aspect ratio flying wing layout aircraft requires special technical verification through sophisticated wind tunnel free flight tests to meet the research needs of its aerodynamic / motion / control coupling characteristics and reduce the development cycle and risks.

[0003] The aerodynamic characteristics of the low aspect ratio flying wing layout have strong nonlinear characteristics. In order to ensure the reliability of high angle of attack flight data, it is extremely important to improve the accuracy of attitude and speed and pressure data during the wind tunnel free flight test. At present, inertial navigation systems and air pressure sensors are usually used to measure the attitude and speed and pressure data in the wind tunnel free flight test of the low aspect ratio flying wing layout. However, the existing technology usually has problems such as data errors, environmental interference has a great impact on data quality, the layout of complex structures is difficult to accurately calibrate, and errors are introduced by the model scaling effect.

[0004] Therefore, a real-time attitude and velocity pressure solution method of the model with low interference and high precision is needed, which is suitable for the wind tunnel free flight test of the small aspect ratio flying wing layout. Summary of the invention

[0005] In order to solve the problems of insufficient anti-interference ability and low precision in the prior art, the present invention provides a real-time attitude and speed pressure solution method for a wind tunnel free flight test model. The method is applicable to a small aspect ratio flying wing layout wind tunnel free flight test, and comprises the following steps:

[0006] S1: Select three pressure measuring holes on the surface of the aircraft to be tested, wherein the three pressure measuring holes are pressure measuring hole I, pressure measuring hole II and pressure measuring hole III;

[0007] The pressure measuring hole I is located at the nose tip of the aircraft to be tested, the pressure measuring hole II is located at the lower left wing surface of the aircraft to be tested, and the pressure measuring hole III is located at the lower right wing surface of the aircraft to be tested, and is symmetrically distributed with the pressure measuring hole II;

[0008] S2: Processing lightweight and low inertia geometrically similar wind tunnel test model;

[0009] S3: The lightweight and small inertia geometrically similar wind tunnel test model is connected to the wind tunnel support system via a six-component strain gauge balance, and data is collected using a wind tunnel test data acquisition system;

[0010] S4: determining the test attitude angle envelope range of the aircraft to be tested, and changing the model attitude angle through the wind tunnel support system to reach the target attitude position;

[0011] S5: collecting the pressure coefficients of the three pressure measuring holes within the range of the attitude angle envelope;

[0012] S6: Calculating the sideslip angle calibration coefficient, the angle of attack calibration coefficient and the velocity pressure calibration coefficient according to the pressure coefficients of the three pressure measuring holes;

[0013] S7: Calculate the sideslip angle, angle of attack and incoming wind speed of the aircraft to be tested according to the sideslip angle calibration coefficient, angle of attack calibration coefficient and speed pressure calibration coefficient.

[0014] Furthermore, in S1, the diameters of the three pressure measuring holes are 0.4 to 0.8 mm, the axes of the holes are perpendicular to the local surface, the deflection angle does not exceed ±3°, and the hole openings are kept flush with the surface of the aircraft to be tested.

[0015] Further, in S6, the sideslip angle calibration coefficient is obtained by:

[0016] ;

[0017] Obtain, among which, is the sideslip angle calibration coefficient at the i-th moment, is the pressure coefficient of pressure measuring holes 1, 2 and 3 at the i-th moment.

[0018] Further, in S6, the angle of attack calibration coefficient is obtained by:

[0019] ;

[0020] Obtain, among which, is the sideslip angle at the i-th moment, for The angle of attack calibration coefficient at the i-th moment in the state.

[0021] Further, in S6, the speed pressure calibration coefficient is obtained by:

[0022] ;

[0023] Obtain, among which, is the speed and pressure calibration coefficient at the i-th moment.

[0024] Furthermore, the sideslip angle is calculated by:

[0025] ;

[0026] Obtain, among which, , For distance The nearest adjacent sideslip angle, and , , is the corresponding calibration factor.

[0027] Furthermore, the angle of attack is determined by:

[0028] ;

[0029] ;

[0030] Obtain, among which, is the angle of attack at the i-th moment, for The full angle of attack calibration coefficient under the state, for The full angle of attack calibration coefficient under the state, for , The angle of attack calibration coefficient under the state, for , The angle of attack calibration coefficient under the state, , For distance The nearest neighboring angle of attack, and , is the correction factor.

[0031] Furthermore, the incoming wind speed is:

[0032] ;

[0033] Obtain, among which, for The speed pressure calibration coefficient under the state, for , The speed pressure calibration coefficient under the state, for , The speed pressure calibration coefficient under the state, is the incoming wind speed at the i-th moment, , For distance The nearest adjacent incoming wind speed, and .

[0034] Advantages and beneficial effects of the present invention: The present invention establishes a real-time attitude and speed-pressure solution method for a wind tunnel free flight test model of a small aspect ratio flying wing layout. Compared with traditional atmospheric data solution methods, this method can more accurately ensure the reliability of high angle of attack flight data, avoid the problems of limited measurement range and reduced accuracy due to the influence of an external sensor system on the aerodynamic shape, meet the demand for accurate measurement of attitude data due to the strong nonlinear characteristics of the small aspect ratio flying wing layout, and improve the reliability of the wind tunnel free flight test data of this layout. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the process of the present invention;

[0036] Figure 2 is the calibration factor Solve the comparison chart;

[0037] Figure 3 is the calibration factor Solve the comparison chart. DETAILED DESCRIPTION

[0038] Example 1: Combination Figure 1 This embodiment describes a method for calculating the real-time attitude and speed pressure of a wind tunnel free flight test model. The method is applicable to a wind tunnel free flight test of a small aspect ratio flying wing layout, and includes the following steps:

[0039] S1: Select three pressure measuring holes on the surface of the aircraft to be tested, wherein the three pressure measuring holes are pressure measuring hole I, pressure measuring hole II and pressure measuring hole III;

[0040] The pressure measuring hole I is located at the nose tip of the aircraft to be tested, the pressure measuring hole II is located at the lower left wing surface of the aircraft to be tested, and the pressure measuring hole III is located at the lower right wing surface of the aircraft to be tested, and is symmetrically distributed with the pressure measuring hole II;

[0041] S2: Processing lightweight and low inertia geometrically similar wind tunnel test model;

[0042] S3: The lightweight and small inertia geometrically similar wind tunnel test model is connected to the wind tunnel support system via a six-component strain gauge balance, and data is collected using a wind tunnel test data acquisition system;

[0043] S4: determining the test attitude angle envelope range of the aircraft to be tested, and changing the model attitude angle through the wind tunnel support system to reach the target attitude position;

[0044] S5: collecting the pressure coefficients of the three pressure measuring holes within the range of the attitude angle envelope;

[0045] S6: Calculating the sideslip angle calibration coefficient, the angle of attack calibration coefficient and the velocity pressure calibration coefficient according to the pressure coefficients of the three pressure measuring holes;

[0046] S7: Calculate the sideslip angle, angle of attack and incoming wind speed of the aircraft to be tested according to the sideslip angle calibration coefficient, angle of attack calibration coefficient and speed pressure calibration coefficient.

[0047] Specifically, in S1, the three pressure measuring holes are selected according to the following criteria:

[0048] 1) Within the stable flow field characteristics;

[0049] 2) Avoid turbulent areas in the air intake;

[0050] 3) Avoid being affected by rudder surface deflection;

[0051] 4) It should be arranged preferentially in areas where surface pressure changes are more obvious.

[0052] In S3, the wind tunnel test data acquisition system has the function of real-time synchronous acquisition of balance data and model motion posture.

[0053] In S5, the pressure coefficient needs to be corrected for the average airflow angle, converted for the two center distances, and converted for the axis system.

[0054] In S1, the diameters of the three pressure measuring holes are 0.4 to 0.8 mm, the axes of the holes are perpendicular to the local surface, the deflection angle does not exceed ±3°, and the hole openings are kept flush with the surface of the aircraft to be tested.

[0055] Further, in S6, the sideslip angle calibration coefficient is obtained by:

[0056] ;

[0057] Obtain, among which, is the sideslip angle calibration coefficient at the i-th moment, is the pressure coefficient of pressure measuring holes 1, 2 and 3 at the i-th moment.

[0058] In S6, the angle of attack calibration coefficient is obtained by:

[0059] ;

[0060] Obtain, among which, is the sideslip angle at the i-th moment, for The angle of attack calibration coefficient at the i-th moment in the state.

[0061] Further, in S6, the speed pressure calibration coefficient is obtained by:

[0062] ;

[0063] Obtain, among which, is the speed and pressure calibration coefficient at the i-th moment.

[0064] Furthermore, the sideslip angle is calculated by:

[0065] ;

[0066] Obtain, among which, , For distance The nearest adjacent sideslip angle, and , , is the corresponding calibration factor.

[0067] The angle of attack is given by:

[0068] ;

[0069] ;

[0070] Obtain, among which, is the angle of attack at the i-th moment, for The full angle of attack calibration coefficient under the state, for The full angle of attack calibration coefficient under the state, for , The angle of attack calibration coefficient under the state, for , The angle of attack calibration coefficient under the state, , For distance The nearest neighboring angle of attack, and , is the correction factor.

[0071] The incoming wind speed is:

[0072] ;

[0073] Obtain, among which, for The speed pressure calibration coefficient under the state, for , The speed pressure calibration coefficient under the state, for , The speed pressure calibration coefficient under the state, is the incoming wind speed at the i-th moment, , For distance The nearest adjacent incoming wind speed, and .

[0074] Specifically, Figure 2 and Figure 3 As shown in Table 1 and Table 2, the calibration coefficients obtained by solving are basically consistent with the calibration coefficients obtained by experimental test. The maximum solution error is 0.89° (when the sideslip angle is 16°), and the angle of attack The maximum solution error is 1.6° (at an angle of attack of 25°). The results show that the real-time attitude and velocity pressure solution method of the wind tunnel free flight test model of the small aspect ratio flying wing layout can accurately guarantee the reliability of the high angle of attack flight data, avoid the problems of limited measurement range and reduced accuracy due to the influence of the external sensor system on the aerodynamic shape, meet the demand for accurate measurement of attitude data due to the strong nonlinear characteristics of the small aspect ratio flying wing layout, and improve the reliability of the wind tunnel free flight test data of this layout.

[0075] Table 1 Sideslip angle Solution comparison

[0076]

[0077] Table 2 Angle of attack Solution comparison

[0078]

[0079] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is selected primarily for readability and teaching purposes, rather than for explaining or defining the subject matter of the present invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is illustrative, not restrictive, with respect to the scope of the present invention, which is defined by the appended claims.

Claims

1. A method for calculating the real-time attitude and speed pressure of a wind tunnel free flight test model, which is applicable to a wind tunnel free flight test of a small aspect ratio flying wing layout, and is characterized in that: The method comprises: S1: Select three pressure measuring holes on the surface of the aircraft to be tested, wherein the three pressure measuring holes are pressure measuring hole 1, pressure measuring hole 2 and pressure measuring hole 3; The pressure measuring hole 1 is located at the nose tip of the aircraft to be tested, the pressure measuring hole 2 is located at the lower left wing surface of the aircraft to be tested, and the pressure measuring hole 3 is located at the lower right wing surface of the aircraft to be tested, and is symmetrically distributed with the pressure measuring hole 2; S2: Processing lightweight and low inertia geometrically similar wind tunnel test model; S3: The lightweight and small inertia geometrically similar wind tunnel test model is connected to the wind tunnel support system via a six-component strain gauge balance, and data is collected using a wind tunnel test data acquisition system; S4: determining the test attitude angle envelope range of the aircraft to be tested, and changing the model attitude angle through the wind tunnel support system to reach the target attitude position; S5: collecting the pressure coefficients of the three pressure measuring holes within the range of the attitude angle envelope; S6: Calculating the sideslip angle calibration coefficient, the angle of attack calibration coefficient and the velocity pressure calibration coefficient according to the pressure coefficients of the three pressure measuring holes; S7: Calculating the sideslip angle, angle of attack and incoming wind speed of the aircraft to be tested according to the sideslip angle calibration coefficient, angle of attack calibration coefficient and speed pressure calibration coefficient; The sideslip angle is given by: Get, where β i is the sideslip angle at the i-th moment, β1 and β2 are the distances β i The nearest adjacent sideslip angle, and β1<β2, is the corresponding calibration coefficient; The angle of attack is given by: Get, where, where α i is the angle of attack at the i-th moment, k α (β1) is the full angle of attack calibration coefficient in the β1 state, k α (β2) is the full angle of attack calibration coefficient in the β2 state, α2, β i The angle of attack calibration coefficient under the state, α1, β i The angle of attack calibration coefficients under the state, α1, α2 are the distance α i The nearest adjacent angle of attack, with α1<α2, k ε is the correction factor; The incoming wind speed is: Obtain, among which, is α i Speed ​​pressure calibration coefficient under the state, V1, α i Speed ​​pressure calibration coefficient under the state, V2, α i Speed ​​pressure calibration coefficient under the state, V i is the incoming wind speed at the i-th moment, V1 and V2 are the distances V i The nearest adjacent incoming wind speed, with V1<V2.

2. The method for calculating the real-time attitude and velocity pressure of a wind tunnel free flight test model according to claim 1, characterized in that: In S1, the diameters of the three pressure measuring holes are 0.4 to 0.8 mm, the axes of the holes are perpendicular to the local surface, the deflection angle does not exceed ±3°, and the hole openings are kept flush with the surface of the aircraft to be tested.

3. The method for calculating the real-time attitude and velocity pressure of a wind tunnel free flight test model according to claim 1, characterized in that: In S6, the sideslip angle calibration coefficient is obtained by: Obtain, among which, is the sideslip angle calibration coefficient at the i-th moment, is the pressure coefficient of pressure measuring holes 1, 2 and 3 at the i-th moment.

4. A method for calculating the real-time attitude and velocity pressure of a wind tunnel free flight test model according to claim 3, characterized in that: In S6, the angle of attack calibration coefficient is obtained by: Obtain, among which, β i The angle of attack calibration coefficient at the i-th moment in the state.

5. A method for calculating the real-time attitude and velocity pressure of a wind tunnel free flight test model according to claim 4, characterized in that: In S6, the speed pressure calibration coefficient is obtained by: Obtain, among which, is the speed and pressure calibration coefficient at the i-th moment.

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