An aerodynamic structure measurement system and method for ultra-high speed, high enthalpy flow field environments

Abstract

This invention relates to an aerodynamic structure measurement system and method for ultra-high-speed, high-enthalpy flow environments. The target model is placed between two wind tunnel windows, coinciding with their central axes. A reflector is placed on one side of the test section, its central axis coinciding with the central axis of the wind tunnel window. A knife-edge device and an illumination source are placed side-by-side at the focal point of the reflector on the other side of the test section. Light emitted from the illumination source is refocused at the focal point of the reflector via a light-adjusting device and the reflector, then passes through the knife-edge device and is captured by a high-speed camera. A narrow-band filter is installed in front of the high-speed camera lens to filter out other self-luminous light from the flow field. The high-speed camera and the illumination source are connected via a synchronizer. A workstation is connected to the high-speed camera to receive images captured by the camera for aerodynamic structure analysis. This invention solves the problem of existing technologies being unable to measure the aerodynamic structures in ultra-high-speed, high-enthalpy flow fields.

Description

Technical Field

[0001] This invention belongs to the field of ultra-high speed and high enthalpy flow field testing technology, and relates to an aerodynamic structure measurement system and method for ultra-high speed and high enthalpy flow field environments. Background Technology

[0002] As aircraft develop towards higher speeds, the resulting aerodynamic and thermal simulation challenges need to be addressed. Currently, ground-based equipment such as ultra-high-speed, high-enthalpy shock tunnels are mainly used to simulate the aerodynamic and thermal environments encountered by these aircraft. However, these wind tunnels have short effective timeframes and exhibit strong self-luminescence. Therefore, measuring the aerodynamic structure of aircraft becomes a significant challenge. Summary of the Invention

[0003] The technical problem solved by this invention is: to address the characteristics of short effective flow field time and strong self-luminescence in high-enthalpy flow fields simulated in ultra-high-speed, high-enthalpy shock tunnels, an aerodynamic structure measurement system and method for ultra-high-speed, high-enthalpy flow field environments are proposed, solving the problem that existing technologies cannot measure aerodynamic structures in ultra-high-speed, high-enthalpy flow fields.

[0004] The solution of the present invention is: an aerodynamic structure measurement system for ultra-high speed and high enthalpy flow field environment, including a high-speed camera, an illumination source, an illumination adjustment device, a reflector, two wind tunnel windows, a target model, a narrow band filter, a knife edge device, a synchronizer and a workstation;

[0005] The target model is placed between two wind tunnel windows, and the central axes of the target model and the two wind tunnel windows coincide.

[0006] A reflector is placed on one side of the test section, with its central axis coinciding with the central axis of the wind tunnel window. The knife-edge device and the illumination source are placed side by side at the focal point of the reflector on the other side of the test section. The light emitted by the illumination source passes through the light adjustment device and the reflector, and under the reflection of the reflector, it passes through the two wind tunnel windows and converges again at the focal point of the reflector. Then, it passes through the knife-edge device and is captured by a high-speed camera. The light adjustment device is used to change the light emitted by the illumination source from a point source to a vertical line source.

[0007] A narrowband filter is installed in front of the lens of a high-speed camera to allow light generated by the illumination source to pass through while filtering out other self-luminous flow fields.

[0008] The high-speed camera and the illumination source are connected via a synchronizer to enable them to operate at the same frequency.

[0009] The workstation connects to a high-speed camera to receive images captured by the camera and perform aerodynamic structure analysis.

[0010] Furthermore, the internal parameters and communication protocol of the high-speed camera and the lighting source are set so that the high-speed camera is the main synchronization device and the lighting source is the controlled device, achieving the effect that the high-speed camera and the lighting source work at the same frequency, and the lighting source is in the light-emitting state when the high-speed camera is exposed, and the lighting source is not in the light-emitting state when the high-speed camera is not exposed.

[0011] Furthermore, the parameter settings for the high-speed camera and the illumination source include: the high-speed camera shooting frequency is not less than 10,000 fps, and the successive exposure time is not more than 1 / 100,000 s; the illumination source emission frequency is not less than the high-speed camera shooting frequency, and the emission duration is not more than the camera exposure time.

[0012] Furthermore, the high-speed camera trigger port is connected to the wind tunnel incoming flow trigger signal via a cable, so that when the flow field is started, the high-speed camera and the illumination source begin to work according to the set parameters.

[0013] Furthermore, the blade device includes two blades and a thread adjustment device. The gap between the two blades is a central slit, and the thread adjustment device is used to adjust the width of the central slit. The width of the central slit of the blade device is not less than the width of the vertical light source.

[0014] Furthermore, the reflector is a concave mirror, the focal length of the reflector is greater than half the width of the test section, and the diameter of the reflector is not less than the diameter of the wind tunnel window.

[0015] Furthermore, the projected area of ​​the target model in the wind tunnel window is no greater than 1 / 2 of the wind tunnel window area.

[0016] Furthermore, the flow field velocity in the ultra-high speed and high enthalpy flow field environment is above 2000 m / s, and the total temperature is above 6000 K.

[0017] A method for measuring aerodynamic structures in ultra-high-speed, high-enthalpy flow environments includes the following steps:

[0018] S1. Determine the wavelength value of the illumination source for the ultra-high speed high enthalpy flow field, and select the illumination source used by the aerodynamic structure measurement system;

[0019] S2. Use the aerodynamic structure measurement system to obtain aerodynamic structure images of the ultra-high speed and high enthalpy flow field environment;

[0020] S3. Filter the aerodynamic structure image, detect the shock boundary layer and target model in the filtered image, and obtain the shock boundary layer contour and model boundary contour.

[0021] S4. Based on the model boundary contour, obtain the known length value of the target model. L Number of pixels in an aerodynamic structure image pixel LThis allows us to obtain the actual length value corresponding to a single pixel. ;

[0022] S5. Compare the pixel position information of the model boundary contour and the shock wave boundary layer contour to obtain the detached shock wave pixel length at the target model stationary point, the target model spanwise boundary layer pixel length, and the pixel difference between the detached shock wave generation location and the target model stationary point location. Then, compare the detached shock wave pixel length, the target model spanwise boundary layer pixel length, and the pixel difference with... Multiplying these values ​​yields the detached shock wave distance, boundary layer thickness, and separation shock wave location, which are used as the final output aerodynamic structural parameters.

[0023] Furthermore, the illumination source used in the aerodynamic structure measurement system includes:

[0024] Measurement of the autoluminescence spectral distribution of an ultra-high-speed, high-enthalpy flow field;

[0025] Spectral curves with a frequency range of 400 nm to 760 nm were extracted from the self-luminous spectral distribution to obtain the visible light spectral intensity curve of the flow field;

[0026] By comparing the wavelengths of all existing lasers with the visible light spectral intensity curve, the relative spectral intensity values ​​of all lasers are obtained. Under the premise of meeting the basic requirements of the laser, the laser with the smallest relative spectral intensity value is selected as the illumination source. The basic requirements of the laser are: it has an external device synchronization function and the synchronization frequency can reach more than 10KHz.

[0027] The advantages of this invention compared to the prior art are:

[0028] This invention employs spectral analysis and image vision methods to achieve the measurement and analysis of aerodynamic structures in ultra-high-speed, high-enthalpy flow fields. Compared with existing technologies, it solves to some extent the aerodynamic structure interference problem caused by flow field self-luminescence, and can quantitatively analyze the aerodynamic structure parameters of ultra-high-speed, high-enthalpy flow fields, providing technical means for the preliminary experimental research of related aircraft. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of an aerodynamic structure measurement system for ultra-high speed, high enthalpy flow field environments according to the present invention;

[0030] Figure 2 This is a flowchart of an aerodynamic structure measurement method for ultra-high speed, high enthalpy flow field environment according to the present invention;

[0031] In the diagram: 1-High-speed camera, 2-Illumination source, 3-Light adjustment device, 4-Reflector, 5-Wind tunnel window, 6-Target model, 7-Narrowband filter, 8-Knife edge device, 9-Synchronizer, 10-Workstation. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Example 1

[0034] like Figure 1 As shown, the present invention proposes an aerodynamic structure measurement system for ultra-high speed and high enthalpy flow field environment, including a high-speed camera 1, an illumination source 2, an illumination adjustment device 3, a reflector 4, two wind tunnel windows 5, a target model 6, a narrow band filter 7, a knife edge device 8, a synchronizer 9, and a workstation 10.

[0035] The target model 6 is placed between the two wind tunnel windows 5, and the central axes of the target model 6 and the two wind tunnel windows 5 coincide.

[0036] A reflector 4 is placed on one side of the test section, with its central axis coinciding with the central axis of the wind tunnel window 5. A knife-edge device 8 and an illumination source 2 are placed side by side at the focal point of the reflector 4 on the other side of the test section. The light emitted by the illumination source 2 passes through the light adjustment device 3 and the reflector 4, and under the reflection of the reflector 4, it passes through the two wind tunnel windows 5 and converges back to the focal point of the reflector 4. Then, it passes through the knife-edge device 8 and is captured by the high-speed camera 1. The light adjustment device 3 is used to change the light emitted by the illumination source 2 from a point light source to a vertical line light source.

[0037] A narrow-band filter 7 is installed in front of the lens of the high-speed camera 1 to allow light generated by the illumination source 2 to pass through while filtering out other self-luminous flow fields.

[0038] The high-speed camera 1 and the illumination source 2 are connected through a synchronizer 9 to enable the high-speed camera 1 and the illumination source 2 to work at the same frequency;

[0039] Workstation 10 is connected to high-speed camera 1 to receive images captured by high-speed camera 1 and perform aerodynamic structure analysis.

[0040] The internal parameters and communication protocol of the high-speed camera 1 and the illumination source 2 are set so that the high-speed camera 1 is the master synchronization device and the illumination source 2 is the controlled device, so that the high-speed camera 1 and the illumination source 2 work at the same frequency, and the illumination source 2 is in the light-emitting state when the high-speed camera 1 is exposed, and the illumination source 2 is not in the light-emitting state when the high-speed camera 1 is not exposed.

[0041] Preferably, the high-speed camera 1 has a shooting frequency of not less than 10,000 fps and a successive exposure time of not more than 1 / 100,000 s; the illumination source 2 has a light emission frequency of not less than the shooting frequency of the high-speed camera 1 and a light emission duration of not more than the camera exposure time.

[0042] The high-speed camera 1 trigger port is connected to the wind tunnel incoming flow trigger signal via a cable, so that when the flow field is started, the high-speed camera 1 and the illumination source 2 start working according to the set parameters.

[0043] The blade device 8 includes two blades and a thread adjustment device. The gap between the two blades is a central slit, and the thread adjustment device is used to adjust the width of the central slit. The width of the central slit of the blade device 8 is not less than the width of the vertical light source.

[0044] The reflector 4 is a concave mirror, the focal length of the reflector 4 is greater than half the width of the test section, and the diameter of the reflector 4 is not less than the diameter of the wind tunnel window 5.

[0045] The projected area of ​​the target model 6 in the wind tunnel window 5 is no greater than 1 / 2 of the area of ​​the wind tunnel window 5.

[0046] The ultra-high speed and high enthalpy flow field environment has a flow field velocity of over 2000 m / s and a total temperature of over 6000 K.

[0047] Based on the aforementioned aerodynamic structure measurement system, this embodiment also proposes an aerodynamic structure measurement method for ultra-high speed, high enthalpy flow field environments, such as... Figure 2 As shown, it includes the following steps:

[0048] S1. Determine the wavelength value of the illumination source for the ultra-high speed high enthalpy flow field, and select the illumination source 2 used in the aerodynamic structure measurement system.

[0049] Step S1 specifically includes:

[0050] 110. Measure the autoluminescence spectrum distribution of an ultra-high-speed, high-enthalpy flow field;

[0051] 120. Extract the spectral curve with a frequency range of 400nm~760nm from the self-luminous spectral distribution to obtain the visible light spectral intensity curve of the flow field;

[0052] 130. Search the market for existing single-wavelength laser products. Compare the wavelengths of all existing lasers with the visible light spectral intensity curve to obtain the relative spectral intensity values ​​for all lasers. Under the premise of meeting the basic requirements of the laser, select the laser with the lowest relative spectral intensity value as the illumination source 2. The basic requirements for the laser are: it must have an external device synchronization function, and the synchronization frequency must be at least 10kHz.

[0053] S2. Use the aerodynamic structure measurement system to obtain aerodynamic structure images of the ultra-high speed and high enthalpy flow field environment.

[0054] Step S2 specifically includes:

[0055] 210. Before starting the flow field, place the reflector 4 on one side of the test section, so that the central axis of the reflector 4 coincides with the central axis of the wind tunnel window 5. Place the knife-edge device 8 and the illumination source 2 side by side at the focal position of the reflector 4 on the other side of the test section.

[0056] 220. Turn on the lighting source 2. The light emitted by the light source passes through the light adjustment device 3 and the reflector 4, and is refocused at the focal position of the reflector 4. Then it passes through the knife-edge device 8 and is captured by the high-speed camera 1.

[0057] 230. Adjust the distance between the lighting source 2 and the reflector 4 so that the focal point of the reflected light passes through the central slit of the knife-edge device 8.

[0058] 240. Parameter settings for high-speed camera 1 and illumination source 2. The shooting frequency of high-speed camera 1 is no less than 10,000 fps, and the successive exposure time is no more than 1 / 100,000 s. The light emission frequency of illumination source 2 is no less than the shooting frequency of high-speed camera 1, and the light emission duration is no more than the camera's exposure time.

[0059] 250. High-speed camera 1 and illumination source 2 are synchronized. High-speed camera 1 and illumination source 2 are connected via synchronizer 9, and the internal parameters and communication protocols of the two devices are set so that high-speed camera 1 is the master synchronizing device and illumination source 2 is the controlled device. This achieves the effect of the two devices working at the same frequency, and illumination source 2 is in the light-emitting state when high-speed camera 1 is being exposed, and illumination source 2 is not emitting light when high-speed camera 1 is not being exposed.

[0060] 260. Install the narrowband filter 7 in front of the lens of the high-speed camera 1, and connect the wind tunnel incoming flow trigger signal to the trigger port of the high-speed camera 1 through a cable, so that when the flow field is started, the high-speed camera 1 and the illumination source 2 start working according to the set parameters.

[0061] 270. Flow field activation: The wind tunnel inflow trigger signal activates high-speed camera 1 and illumination source 2. The light source illuminates the wind tunnel flow field, and high-speed camera 1 acquires images containing aerodynamic structures. After the wind tunnel flow field is activated, the aerodynamic structure images from high-speed camera 1 are saved to workstation 10 for aerodynamic structure analysis.

[0062] S3. Filter the aerodynamic structure image, and detect the shock boundary layer and target model 6 in the filtered image to obtain the shock boundary layer contour and model boundary contour.

[0063] Step S3 specifically includes:

[0064] 310. Use the following functions to filter the image, where This represents the filtered pixel value at position (x, y) in the image. The pixel value at position (x,y) before filtering. For filtering window, This is the mean value of all pixels within the filtering window. The noise variance of the image before filtering. This represents the variance of pixel values ​​within the filtering window.

[0065]

[0066] 320. Based on the Matlab development platform, use the "edge" function and the "canny" operator to detect the shock boundary layer and target model 6 in the filtered image, and obtain the shock boundary layer contour and the model boundary contour.

[0067] S4. Based on the model boundary contour, obtain the known length value of target model 6. L The number of pixels (e.g., the length of the entire target model 6) in the aerodynamic structure image. pixel L This allows us to obtain the actual length value corresponding to a single pixel. .

[0068] S5. Compare the pixel position information of the model boundary contour and the shock wave boundary layer contour to obtain the detached shock wave pixel length at the target model stationary point, the target model spanwise boundary layer pixel length, and the pixel difference between the detached shock wave generation location and the target model stationary point location. Then, compare the detached shock wave pixel length, the target model spanwise boundary layer pixel length, and the pixel difference with... Multiplying these values ​​yields the detached shock wave distance, boundary layer thickness, and separation shock wave location, which are used as the final output aerodynamic structural parameters.

[0069] The system and method proposed in this invention can quantitatively analyze aerodynamic structural parameters, solving the problem that existing technologies cannot measure aerodynamic structures in ultra-high speed, high enthalpy flow fields.

[0070] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

[0071] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. An aerodynamic structure measurement system for ultra-high speed, high enthalpy flow field environments, characterized in that, It includes a high-speed camera (1), an illumination source (2), a light adjustment device (3), a reflector (4), two wind tunnel windows (5), a target model (6), a narrowband filter (7), a knife-edge device (8), a synchronizer (9), and a workstation (10). The target model (6) is placed between two wind tunnel windows (5), and the central axes of the target model (6) and the two wind tunnel windows (5) coincide. The reflector (4) is placed on one side of the test section, and the central axis of the reflector (4) coincides with the central axis of the wind tunnel window (5). The knife-edge device (8) and the illumination source (2) are placed side by side at the focal position of the reflector (4) on the other side of the test section. The light emitted by the illumination source (2) passes through the light adjustment device (3) and the reflector (4), and under the reflection of the reflector (4), it passes through the two wind tunnel windows (5) and converges again at the focal position of the reflector (4). Then it passes through the knife-edge device (8) and is captured by the high-speed camera (1). The light adjustment device (3) is used to change the light emitted by the illumination source (2) from a point source to a vertical line source. A narrow-band filter (7) is installed in front of the lens of a high-speed camera (1) to allow light generated by the illumination source (2) to pass through while filtering out other self-luminous flow fields; The high-speed camera (1) and the illumination source (2) are connected through a synchronizer (9) to enable the high-speed camera (1) and the illumination source (2) to work at the same frequency; The workstation (10) is connected to the high-speed camera (1) to receive images captured by the high-speed camera (1) and perform aerodynamic structure analysis.

2. The aerodynamic structure measurement system for ultra-high speed, high enthalpy flow field environment according to claim 1, characterized in that, Set the internal parameters and communication protocol of the high-speed camera (1) and the lighting source (2) so that the high-speed camera (1) is the main synchronization device and the lighting source (2) is the controlled device, so that the high-speed camera (1) and the lighting source (2) work at the same frequency, and the lighting source (2) is in the light-emitting state when the high-speed camera (1) is exposed, and the lighting source (2) does not emit light when the high-speed camera (1) is not exposed.

3. The aerodynamic structure measurement system for ultra-high speed, high enthalpy flow field environment according to claim 2, characterized in that, The parameter settings for the high-speed camera (1) and the illumination source (2) include: the shooting frequency of the high-speed camera (1) is not less than 10,000 fps and the successive exposure time is not more than 1 / 100,000 s; the light emission frequency of the illumination source (2) is not less than the shooting frequency of the high-speed camera (1) and the light emission duration is not more than the camera exposure time.

4. The aerodynamic structure measurement system for ultra-high speed, high enthalpy flow field environment according to claim 1, characterized in that, The high-speed camera (1) trigger port is connected to the wind tunnel incoming flow trigger signal via a cable, so that when the flow field starts, the high-speed camera (1) and the illumination source (2) start working according to the set parameters.

5. The aerodynamic structure measurement system for ultra-high speed, high enthalpy flow field environment according to claim 1, characterized in that, The blade device (8) includes two blades and a thread adjustment device. The gap between the two blades is a central slit. The thread adjustment device is used to adjust the width of the central slit. The width of the central slit of the blade device (8) is not less than the width of the vertical light source.

6. The aerodynamic structure measurement system for ultra-high speed, high enthalpy flow field environment according to claim 1, characterized in that, The reflector (4) is a concave mirror, the focal length of the reflector (4) is greater than half the width of the test section, and the diameter of the reflector (4) is not less than the diameter of the wind tunnel window (5).

7. The aerodynamic structure measurement system for ultra-high speed, high enthalpy flow field environment according to claim 1, characterized in that, The projected area of ​​the target model (6) in the wind tunnel window (5) is no greater than 1 / 2 of the area of ​​the wind tunnel window (5).

8. The aerodynamic structure measurement system for ultra-high speed, high enthalpy flow field environment according to claim 1, characterized in that, The ultra-high speed and high enthalpy flow field environment has a flow field velocity of over 2000 m / s and a total temperature of over 6000 K.

9. A method for measuring aerodynamic structures in an ultra-high-speed, high-enthalpy flow field environment based on the system described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Determine the wavelength value of the illumination source for the ultra-high speed high enthalpy flow field and select the illumination source used in the aerodynamic structure measurement system (2). S2. Use the aerodynamic structure measurement system to obtain aerodynamic structure images of the ultra-high speed and high enthalpy flow field environment; S3. Filter the aerodynamic structure image, and detect the shock boundary layer and target model (6) in the filtered image to obtain the shock boundary layer contour and model boundary contour. S4. Based on the model boundary contour, obtain the known length value of the target model (6). L Number of pixels in an aerodynamic structure image pixel L This allows us to obtain the actual length value corresponding to a single pixel. ; S5. Compare the pixel position information of the model boundary contour and the shock wave boundary layer contour to obtain the detached shock wave pixel length at the target model stationary point, the target model spanwise boundary layer pixel length, and the pixel difference between the detached shock wave generation location and the target model stationary point location. Then, compare the detached shock wave pixel length, the target model spanwise boundary layer pixel length, and the pixel difference with... Multiplying these values ​​yields the detached shock wave distance, boundary layer thickness, and separation shock wave location, which are used as the final output aerodynamic structural parameters.

10. The aerodynamic structure measurement method for ultra-high speed, high enthalpy flow field environment according to claim 9, characterized in that, The illumination source (2) used in the aerodynamic structure measurement system is selected, including: Measurement of the autoluminescence spectral distribution of an ultra-high-speed, high-enthalpy flow field; Spectral curves with a frequency range of 400 nm to 760 nm were extracted from the self-luminous spectral distribution to obtain the visible light spectral intensity curve of the flow field; By comparing all existing laser wavelengths with the visible light spectral intensity curve, the relative spectral intensity values ​​of all lasers are obtained. Under the premise of meeting the basic requirements of lasers, the laser with the smallest relative spectral intensity value is selected as the illumination source (2). The basic requirements of the laser are: it has the function of external device synchronization and the synchronization frequency can reach more than 10KHz.

Images