A gust flow field calibration and characteristic analysis method based on a swing vane type gust generator

Abstract

A kind of gust flow field calibration and characteristic analysis method based on swing vane type gust generator belongs to the technical field of low-speed wind tunnel non-uniform flow field calibration test.To solve the influence law of intuitively analyzing each characteristic parameter on gust flow field characteristics, the invention includes establishing the mathematical model of gust flow field of swing vane type gust generator; installing swing vane type gust generator and flow field calibration system; after starting wind tunnel to target wind speed, waiting for several seconds to stabilize, controlling swing vane type gust generator to make the blade swing according to sine motion law, then triggering hot-wire anemometer system to collect lateral wind speed, obtaining measurement data; calculating the attenuation coefficient of gust flow field; for different measurement positions of gust flow field, calculating the attenuation coefficient of gust flow field, carrying out gust flow field calibration and characteristic analysis, including gust flow field speed analysis and gust flow field frequency analysis.The invention effectively improves the application efficiency of gust wind tunnel test.

Description

Technical Field

[0001] This invention belongs to the technical field of non-uniform flow field calibration and testing in low-speed wind tunnels, specifically relating to a method for gust flow field calibration and characteristic analysis based on a swing blade gust generator. Background Technology

[0002] Non-uniform flow field simulation testing technology is a special dynamic wind tunnel testing technique. It primarily involves placing an airflow interference device at the entrance of the wind tunnel test section. After a uniform inflow passes through this device, a specific non-uniform flow field is formed behind the test section, thus realistically simulating the complex non-uniform flow field environment encountered by an aircraft during flight. Gust flow fields, as a typical type of non-uniform flow field, have important applications in assessing the safety of aircraft in complex wind field environments, and gust flow field calibration methods are one of the most important key technologies. Currently, research on gust flow fields both domestically and internationally often relies on gust flow field calibration experiments, employing a method of sequentially measuring the flow field envelope under different conditions (different wind speeds, blade oscillation amplitudes, and frequencies). While this method yields relatively detailed gust flow field results, it suffers from problems such as high workload, long cycle time, low efficiency, and significant resource waste. Furthermore, it cannot quickly complete gust flow field performance evaluation in the early design stages. Additionally, when studying the relationship between gust flow field characteristics and generator characteristic parameters, it relies entirely on data fitting analysis, lacking a clear physical interpretation. Summary of the Invention

[0003] The problem this invention aims to solve is to intuitively analyze the influence of various characteristic parameters on the characteristics of gust flow field, and proposes a method for gust flow field calibration and characteristic analysis based on a swing blade type gust generator.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for calibrating and analyzing the characteristics of gust flow field based on a oscillating blade gust generator includes the following steps:

[0006] S1. Establish a mathematical model of the gust flow field of the oscillating blade gust generator;

[0007] S2. Install a oscillating blade gust generator and a flow field calibration system;

[0008] S3. After starting the wind tunnel to the target wind speed, wait a few seconds until it stabilizes, control the oscillating blade gust generator to make the blades oscillate according to the sinusoidal motion law, and then trigger the hot-wire speed measurement system to collect lateral wind speed and obtain measurement data;

[0009] S4. Based on the measurement data obtained in step S3, calculate the attenuation coefficient of the gust flow field;

[0010] S5. For different measurement locations of the gust flow field, calculate the attenuation coefficient of the gust flow field based on the method in step S4, and perform gust flow field calibration and characteristic analysis, including gust flow field velocity analysis and gust flow field frequency analysis.

[0011] Furthermore, the specific implementation method of step S1 includes the following steps:

[0012] S1.1. Set the blade swing angle of the oscillating blade gust generator. The expression is:

[0013]

[0014] in, f is the amplitude of the blade swing angle, f is the oscillation frequency, and t is the time.

[0015] S1.2. Differentiate the blade swing angle of the oscillating blade gust generator obtained in step S1.1 over time t to obtain the oscillation angular velocity at the blade trailing edge. The expression is:

[0016] ;

[0017] Then calculate the tangential velocity V1 at the trailing edge of the blade, as expressed by:

[0018]

[0019] Where L is the blade chord length;

[0020] S1.3. Based on the fact that the incoming airflow velocity V0 is deflected after passing over the blade surface, a vertical velocity component V of the incoming airflow velocity is generated. 0y The expression is:

[0021] ;

[0022] Calculate the velocity component V1 of the blade trailing edge on the y-axis. 1y The expression is:

[0023] ;

[0024] S1.4. The vertical velocity component of the incoming airflow velocity and the velocity component of the tangential velocity V1 at the blade trailing edge on the y-axis are summed to obtain the gust flow field velocity at the trailing edge of the gust generator blade, expressed as:

[0025] ;

[0026] Then, the gust velocity at any location of the gust generator is calculated based on the gust flow field velocity at the trailing edge of the gust generator blades. The expression is:

[0027]

[0028] Where K is the attenuation coefficient of the gust flow field.

[0029] Furthermore, the oscillating blade gust generator mentioned in step S2 is arranged at the entrance of the wind tunnel test section. The initial position of the blades in the oscillating blade gust generator is defined as being parallel to the horizontal plane of the wind tunnel, and this position is set as the zero position of the flat plate. The flow field calibration system consists of a hot wire velocity measurement system and a moving test frame. The moving test frame has a three-degree-of-freedom movement function. A two-dimensional hot wire probe is installed on the moving test frame and connected to the hot wire velocity measurement system. The direction of the two-dimensional hot wire probe is adjusted to measure the lateral wind speed.

[0030] Furthermore, the specific implementation method of step S3 is as follows: after starting the wind tunnel to the target wind speed, wait several seconds until it stabilizes, and control the gust generator to make the blades swing according to a sinusoidal motion law, with the blade swing angle being... Then, the hotline speed measurement system is triggered to collect data at a frequency of 200Hz for 20 seconds, thus obtaining the measurement data.

[0031] Furthermore, the specific implementation method of step S4 includes the following steps:

[0032] S4.1. Perform a Fast Fourier Transform on the measurement data Data obtained in step S3 to obtain the dominant frequency F, and calculate the amplitude A of the data change, expressed as:

[0033]

[0034] in, and These represent the maximum and minimum values ​​of the measured data, Data, respectively.

[0035]

[0036]

[0037] in, It is a function with maximum value. It is a minimum value function;

[0038] S4.2. Calculate the gust velocity V at any location of the gust generator. y The amplitude A' is expressed as:

[0039] ;

[0040] S4.3. Based on the amplitude A of data changes and the gust velocity V at any location of the gust generator. y The amplitudes are equal to A', thus obtaining

[0041]

[0042] The formula for calculating the attenuation coefficient of the gust flow field after processing is as follows:

[0043] .

[0044] Furthermore, the specific implementation method of step S5 includes the following steps:

[0045] S5.1. Move the two-dimensional hot wire probe to the measurement point position, and repeat steps S3 and S4 to obtain the gust flow field attenuation coefficient corresponding to different measurement positions;

[0046] S5.2. Adjust gust speed Expanding the formula, we get the expression:

[0047]

[0048] Then, the identity is derived as follows:

[0049]

[0050] in, The wind speed is a function of time.

[0051] S5.3. Based on the application scenarios and engineering experience of the oscillating blade gust generator, when analyzing the gust flow field characteristics, the gust velocity in step S5.2 will be included. Simplifying the formula, we get

[0052]

[0053] in, Simplified gust speed;

[0054] Based on the above, the gust amplitude and the incoming wind speed are obtained. and swing angle amplitude and oscillation frequency The value increases linearly with the increase of the incoming flow velocity, is positively correlated with the blade sway angle amplitude, and is less affected by the blade oscillation frequency. Based on the obtained characteristic conclusions, engineers can be guided to achieve rapid adjustment of the convective airflow field.

[0055] The beneficial effects of this invention are:

[0056] The present invention describes a method for gust flow field calibration and characteristic analysis based on a oscillating blade gust generator. Starting from the principle of gust flow field generation and based on the motion equation of the generator blades, it proposes a parameterized modeling method for gust flow field characteristics. Each part of the model has a clear physical meaning. Through this mathematical model, the influence of each characteristic parameter on the characteristics of the gust flow field can be intuitively seen, helping designers to quickly estimate the performance of the gust flow field, efficiently complete gust flow field calibration and testing, and effectively improve the efficiency of gust wind tunnel test applications. Attached Figure Description

[0057] Figure 1 The flowchart shows the method for gust flow field calibration and characteristic analysis based on a oscillating blade gust generator according to the present invention.

[0058] Figure 2 This is a schematic diagram of the structure of the oscillating blade type gust generator described in this invention;

[0059] Among them, 1 is the wind tunnel, 2 is the support frame, 3 is the drive motor, 4 is the blade connecting rod, and 5 is the blade. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described specific embodiments are merely a part of the embodiments of the invention, and not all of them. The components of the specific embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations, and the invention may also have other embodiments.

[0061] Therefore, the following detailed description of specific embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected specific embodiments of the invention. All other specific embodiments obtained by those skilled in the art based on these specific embodiments without inventive effort are within the scope of protection of this invention.

[0062] To further understand the invention's content, features, and effects, the following specific embodiments are provided, along with accompanying drawings. Figure 1 -Appendix Figure 2 Detailed explanation is as follows:

[0063] Example 1:

[0064] A method for calibrating and analyzing the characteristics of gust flow field based on a oscillating blade gust generator includes the following steps:

[0065] S1. Establish a mathematical model of the gust flow field of the oscillating blade gust generator;

[0066] Furthermore, the specific implementation method of step S1 includes the following steps:

[0067] S1.1. Set the blade swing angle of the oscillating blade gust generator. The expression is:

[0068]

[0069] in, f is the amplitude of the blade swing angle, f is the oscillation frequency, and t is the time.

[0070] S1.2. Differentiate the blade swing angle of the oscillating blade gust generator obtained in step S1.1 over time t to obtain the oscillation angular velocity at the blade trailing edge. The expression is:

[0071] ;

[0072] Then calculate the tangential velocity V1 at the trailing edge of the blade, as expressed by:

[0073]

[0074] Where L is the blade chord length;

[0075] S1.3. Based on the fact that the incoming airflow velocity V0 is deflected after passing over the blade surface, a vertical velocity component V of the incoming airflow velocity is generated. 0y The expression is:

[0076] ;

[0077] Calculate the velocity component V1 of the blade trailing edge on the y-axis. 1y The expression is:

[0078] ;

[0079] S1.4. The vertical velocity component of the incoming airflow velocity and the velocity component of the tangential velocity V1 at the blade trailing edge on the y-axis are summed to obtain the gust flow field velocity at the trailing edge of the gust generator blade, expressed as:

[0080] ;

[0081] Then, the gust velocity at any location of the gust generator is calculated based on the gust flow field velocity at the trailing edge of the gust generator blades. The expression is:

[0082]

[0083] Where K is the attenuation coefficient of the gust flow field.

[0084] S2. Install a oscillating blade gust generator and a flow field calibration system;

[0085] Furthermore, the oscillating blade gust generator mentioned in step S2 is arranged at the entrance of the wind tunnel test section. The initial position of the blades in the oscillating blade gust generator is defined as parallel to the horizontal plane of the wind tunnel, and this position is set as the zero position of the flat plate. The flow field calibration system consists of a hot wire velocity measurement system and a moving frame. The moving frame has a three-degree-of-freedom movement function. A two-dimensional hot wire probe is installed on the moving frame and connected to the hot wire velocity measurement system. The direction of the two-dimensional hot wire probe is adjusted to measure the lateral wind speed.

[0086] Furthermore, the oscillating blade gust generator comprises two blades connected by a blade connecting rod, ensuring synchronous oscillation of the two blades. The oscillation amplitude and frequency of the blades are controlled by a drive motor, and the entire device is fixed on a support frame. The initial position of the blades in the generator is defined as parallel to the horizontal plane of the wind tunnel, and this position is set as the zero position of the flat plate. The flow field calibration system is arranged in the downstream test area of ​​the wind tunnel test section.

[0087] S3. After starting the wind tunnel to the target wind speed, wait a few seconds until it stabilizes, control the oscillating blade gust generator to make the blades oscillate according to the sinusoidal motion law, and then trigger the hot-wire speed measurement system to collect lateral wind speed and obtain measurement data;

[0088] Furthermore, the specific implementation method of step S3 is as follows: after starting the wind tunnel to the target wind speed, wait several seconds until it stabilizes, and control the gust generator to make the blades swing according to a sinusoidal motion law, with the blade swing angle being... Then, the hotline speed measurement system is triggered to collect data at a frequency of 200Hz for 20 seconds, thus obtaining measurement data.

[0089] S4. Based on the measurement data obtained in step S3, calculate the attenuation coefficient of the gust flow field;

[0090] Furthermore, the specific implementation method of step S4 includes the following steps:

[0091] S4.1. Perform a Fast Fourier Transform on the measurement data Data obtained in step S3 to obtain the dominant frequency F, and calculate the amplitude A of the data change, expressed as:

[0092]

[0093] in, and These represent the maximum and minimum values ​​of the measured data, Data, respectively.

[0094]

[0095]

[0096] in, It is a function with maximum value. It is a minimum value function;

[0097] S4.2. Calculate the gust velocity V at any location of the gust generator. y The amplitude A' is expressed as:

[0098] ;

[0099] S4.3. Based on the amplitude A of data changes and the gust velocity V at any location of the gust generator. y The amplitudes are equal to A', thus obtaining

[0100]

[0101] The formula for calculating the attenuation coefficient of the gust flow field after processing is as follows:

[0102] .

[0103] S5. For different measurement locations of the gust flow field, calculate the attenuation coefficient of the gust flow field based on the method in step S4, and perform gust flow field calibration and characteristic analysis, including gust flow field velocity analysis and gust flow field frequency analysis.

[0104] Furthermore, the specific implementation method of step S5 includes the following steps:

[0105] S5.1. Move the two-dimensional hot wire probe to the measurement point position, and repeat steps S3 and S4 to obtain the gust flow field attenuation coefficient corresponding to different measurement positions;

[0106] S5.2. Adjust gust speed Expanding the formula, we get the expression:

[0107]

[0108] Then, the identity is derived as follows:

[0109]

[0110] in, The wind speed is a function of time.

[0111] According to the identity, the gust speed is the same at any two time intervals of 1 / f. Based on the above, the gust flow field frequency is the same as the blade oscillation frequency.

[0112] S5.3. Based on the application scenarios and engineering experience of the oscillating blade gust generator, when analyzing the gust flow field characteristics, the gust velocity in step S5.2 will be included. Simplifying the formula, we get

[0113]

[0114] in, Simplified gust speed;

[0115] Based on the above, the gust amplitude and the incoming wind speed are obtained. and swing angle amplitude and oscillation frequency The value increases linearly with the increase of the incoming flow velocity, is positively correlated with the blade sway angle amplitude, and is less affected by the blade oscillation frequency. Based on the obtained characteristic conclusions, engineers can be guided to achieve rapid adjustment of the convective airflow field.

[0116] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0117] Although this application has been described above with reference to specific embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of this application. In particular, as long as there is no structural conflict, the features in the specific embodiments disclosed in this application can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, this application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for calibrating and analyzing the characteristics of gust flow field based on a oscillating blade gust generator, characterized in that, Includes the following steps: S1. Establish a mathematical model of the gust flow field of the oscillating blade gust generator; S2. Install a oscillating blade gust generator and a flow field calibration system; S3. After starting the wind tunnel to the target wind speed, wait a few seconds until it stabilizes, control the oscillating blade gust generator to make the blades oscillate according to the sinusoidal motion law, and then trigger the hot-wire speed measurement system to collect lateral wind speed and obtain measurement data; S4. Based on the measurement data obtained in step S3, calculate the attenuation coefficient of the gust flow field; S5. For different measurement locations of the gust flow field, calculate the attenuation coefficient of the gust flow field based on the method in step S4, and perform gust flow field calibration and characteristic analysis, including gust flow field velocity analysis and gust flow field frequency analysis. The specific implementation method of step S1 includes the following steps: S1.

1. Set the blade swing angle of the oscillating blade gust generator. The expression is: in, f is the amplitude of the blade swing angle, f is the oscillation frequency, and t is the time. S1.

2. Differentiate the blade swing angle of the oscillating blade gust generator obtained in step S1.1 over time t to obtain the oscillation angular velocity at the blade trailing edge. The expression is: ； Then calculate the tangential velocity V1 at the trailing edge of the blade, as expressed by: Where L is the blade chord length; S1.

3. Based on the fact that the incoming airflow velocity V0 is deflected after passing over the blade surface, a vertical velocity component V of the incoming airflow velocity is generated. 0y The expression is: ； Calculate the velocity component V1 of the blade trailing edge on the y-axis. 1y The expression is: ； S1.

4. The vertical velocity component of the incoming airflow velocity and the velocity component of the tangential velocity V1 at the blade trailing edge on the y-axis are summed to obtain the gust flow field velocity at the trailing edge of the gust generator blade, expressed as: ； Then, the gust velocity at any location of the gust generator is calculated based on the gust flow field velocity at the trailing edge of the gust generator blades. The expression is: Where K is the attenuation coefficient of the gust flow field; The specific implementation method of step S4 includes the following steps: S4.

1. Perform a Fast Fourier Transform on the measurement data Data obtained in step S3 to obtain the dominant frequency F, and calculate the amplitude A of the data change, expressed as: in, and These represent the maximum and minimum values ​​of the measured data, Data, respectively. in, It is a function with maximum value. It is a minimum value function; S4.

2. Calculate the gust velocity V at any location of the gust generator. y The amplitude A' is expressed as: ； S4.

3. Based on the amplitude A of data changes and the gust velocity V at any location of the gust generator. y The amplitudes are equal to A', thus obtaining The formula for calculating the attenuation coefficient of the gust flow field after processing is as follows: ； The specific implementation method of step S5 includes the following steps: S5.

1. Move the two-dimensional hot wire probe to the measurement point position, and repeat steps S3 and S4 to obtain the gust flow field attenuation coefficient corresponding to different measurement positions; S5.

2. Adjust gust speed Expanding the formula, we get the expression: Then, the identity is derived as follows: in, The wind speed is a function of time. S5.

3. Based on the application scenarios and engineering experience of the oscillating blade gust generator, when analyzing the gust flow field characteristics, the gust velocity in step S5.2 will be included. Simplifying the formula, we get in, Simplified gust speed; Based on the above, the gust speed and the incoming wind speed are obtained. and swing angle amplitude and oscillation frequency The value increases linearly with the increase of the incoming flow velocity, is positively correlated with the blade sway angle amplitude, and is less affected by the blade oscillation frequency. Based on the obtained characteristic conclusions, engineers can be guided to achieve rapid adjustment of the convective airflow field.

2. The method for gust flow field calibration and characteristic analysis based on a oscillating blade gust generator according to claim 1, characterized in that, In step S2, the oscillating blade gust generator is arranged at the entrance of the wind tunnel test section. The initial position of the blades in the oscillating blade gust generator is defined as parallel to the horizontal plane of the wind tunnel, and this position is set as the zero position of the flat plate. The flow field calibration system consists of a hot wire velocity measurement system and a moving test frame. The moving test frame has a three-degree-of-freedom movement function. A two-dimensional hot wire probe is installed on the moving test frame and connected to the hot wire velocity measurement system. The direction of the two-dimensional hot wire probe is adjusted to measure the lateral wind speed.

3. The method for gust flow field calibration and characteristic analysis based on a oscillating blade gust generator according to claim 2, characterized in that, The specific implementation method of step S3 is as follows: after starting the wind tunnel to the target wind speed, wait for several seconds until it stabilizes, and control the gust generator to make the blades swing according to a sinusoidal motion law. The blade swing angle is... Then, the hotline speed measurement system is triggered to collect data at a frequency of 200Hz for 20 seconds, thus obtaining the measurement data.

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