Pneumatic structure measurement system and method for extremely-high-speed high-enthalpy flow field environment

Abstract

The invention relates to a pneumatic structure measurement system and method for an extremely-high-speed high-enthalpy flow field environment. A target model is arranged between two wind tunnel windows and coincides with the central axes of the two wind tunnel windows; the reflector is placed on one side of the test section, and the central axis of the reflector coincides with the central axis of the wind tunnel window; the knife edge device and the illumination light source are arranged side by side at the focus position of the reflector on the other side of the test section, light emitted by the illumination light source is converged to the focus position of the reflector again through the light adjusting device and the reflector, and then penetrates through the knife edge device to be shot by the high-speed camera; the narrow-band optical filter is installed in front of a high-speed camera lens, and self-luminous light of other flow fields is filtered out through light generated by the illumination light source. The high-speed camera is connected with the illumination light source through a synchronizer; the work station is connected with the high-speed camera and receives images shot by the high-speed camera for pneumatic structure analysis. The problem that the pneumatic structure of the extremely-high-speed high-enthalpy flow field cannot be measured in the prior art is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-high speed and high enthalpy flow field testing, and relates to an aerodynamic structure measurement system and method for an ultra-high speed and high enthalpy flow field environment. Background Art

[0002] As aircraft develop towards higher speeds, the resulting aerodynamic thermal ground simulation problem needs to be solved. Currently, the aerodynamic thermal environment encountered by the above-mentioned aircraft is mainly simulated by ground equipment such as ultra-high-speed high-enthalpy shock wave wind tunnels. However, this type of wind tunnel has a short effective time and is accompanied by strong self-luminescence. Therefore, it has become a difficult problem to measure the aerodynamic structure of the aircraft. Summary of the invention

[0003] The technical problem solved by the present invention is: in view of the characteristics of the high enthalpy flow field simulated by an ultra-high-speed and high-enthalpy shock wave wind tunnel, that is, the effective flow field time is short and accompanied by strong self-luminescence, a system and method for measuring aerodynamic structures in an ultra-high-speed and high-enthalpy flow field environment are proposed, so as to solve the problem that the prior art cannot measure aerodynamic structures in an ultra-high-speed and high-enthalpy flow field.

[0004] The technical solution of the present invention is: an aerodynamic structure measurement system for extremely high-speed and high-enthalpy flow field environment, including a high-speed camera, an illumination light source, a light adjustment device, a reflector, two wind tunnel windows, a target model, a narrow-band filter, a knife-edge device, a synchronizer and a workstation; 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; The reflector is placed on one side of the test section, and the central axis of the reflector coincides with the central axis of the wind tunnel window; the knife-edge device and the illumination light source are placed side by side at the focal position of the reflector on the other side of the test section, and the light emitted by the illumination light source passes through the light modulation device and the reflector, and under the reflection of the reflector, passes through the two wind tunnel windows and converges to the focal position of the reflector again, and then passes through the knife-edge device and is photographed by a high-speed camera; the light modulation device is used to change the light emitted by the illumination light source from a point light source into a vertical line light source; The narrow-band filter is installed in front of the high-speed camera lens to allow the light generated by the illumination source to pass through and filter out the self-luminescence of other flow fields; The high-speed camera and the lighting source are connected through a synchronizer to achieve the same frequency operation of the high-speed camera and the lighting source; The workstation is connected to the high-speed camera and receives images taken by the high-speed camera to perform analysis of the aerodynamic structure.

[0005] 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, so that the high-speed camera and the lighting source work at the same frequency, and the lighting source is in a light-emitting state when the high-speed camera is exposing, and does not emit light when the high-speed camera is not exposing.

[0006] Furthermore, the parameter settings of the high-speed camera and the lighting source include: the shooting frequency of the high-speed camera is not less than 10000fps, and the continuous exposure time is not higher than 1 / 100000s; the light emission frequency of the lighting source is not lower than the shooting frequency of the high-speed camera, and the light emission time is not longer than the camera exposure time.

[0007] Furthermore, the trigger port of the high-speed camera is connected to the flow trigger signal of the wind tunnel through a cable, so that when the flow field is started, the high-speed camera and the illumination light source start working according to the set parameters.

[0008] Furthermore, the knife edge device comprises 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 knife edge device is not less than the width of the vertical light source.

[0009] Furthermore, the reflector is a concave mirror, the focal length of the reflector is greater than half of the width of the test section, and the diameter of the reflector is not less than the diameter of the wind tunnel window.

[0010] Furthermore, the projection area of ​​the target model on the wind tunnel window is not greater than 1 / 2 of the area of ​​the wind tunnel window.

[0011] Furthermore, the flow field velocity of the ultra-high-speed and high-enthalpy flow field environment is above 2000 m / s, and the total temperature is above 6000K.

[0012] A method for measuring an aerodynamic structure in an extremely high-speed and high-enthalpy flow field environment comprises the following steps: S1. Determine the wavelength value of the illumination light source of the extremely high-speed and high-enthalpy flow field, and select the illumination light source used by the aerodynamic structure measurement system; S2. Acquiring an aerodynamic structure image of an extremely high-speed and high-enthalpy flow field environment using the aerodynamic structure measurement system; S3, filtering the aerodynamic structure image, detecting the shock wave boundary layer and the target model in the filtered image, and obtaining the shock wave boundary layer contour and the model boundary contour; S4. Obtain the known length value of the target model based on the model boundary contour L The number of pixels in the aerodynamic structure image pixel L , and then get the actual length value corresponding to a pixel ; S5, comparing the pixel position information of the model boundary contour and the shock wave boundary layer contour to obtain the pixel length of the detached shock wave at the target model stagnation point position, the pixel length of the target model spanwise boundary layer, and the pixel difference between the detached shock wave generation position and the target model stagnation point position, and respectively comparing the pixel length of the detached shock wave, the pixel length of the target model spanwise boundary layer, and the pixel difference with The values ​​are multiplied to obtain the detached shock wave distance, boundary layer thickness and separation shock wave position, which are used as the final output aerodynamic structure parameters.

[0013] Further, the illumination light source used in the aerodynamic structure measurement system is selected, including: Measure the spontaneous luminescence spectrum distribution of extremely high-speed and high-enthalpy flow fields; Extracting a spectrum curve with a frequency range of 400nm to 760nm from the spontaneous luminescence spectrum distribution to obtain a flow field visible light spectrum intensity curve; The wavelengths of all existing lasers are queried against the visible light spectrum intensity curve to obtain the spectral relative intensity values ​​corresponding to all lasers. On the premise of meeting the basic requirements of the laser, the laser with the smallest spectral relative intensity value is selected as the illumination light source; the basic requirements of the laser are: it has the function of synchronizing with external equipment, and the synchronization frequency can reach above 10KHz.

[0014] The beneficial effects of the present invention compared with the prior art are: The present invention adopts spectral analysis and image vision methods to realize the measurement and analysis of the aerodynamic structure of extremely high-speed and high-enthalpy flow fields. Compared with the existing technology, it solves the problem of aerodynamic structure interference caused by self-luminescence of the flow field to a certain extent, and can quantitatively analyze the aerodynamic structure parameters of extremely high-speed and high-enthalpy flow fields, providing technical means for the preliminary experimental research of related aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of an aerodynamic structure measurement system for an extremely high-speed and high-enthalpy flow field environment according to the present invention; Figure 2 This is a flow chart of a method for measuring aerodynamic structures in an extremely high-speed and high-enthalpy flow field environment according to the present invention; In the figure: 1- high-speed camera, 2- illumination light source, 3- light modulation device, 4- reflector, 5- wind tunnel window, 6- target model, 7- narrow band filter, 8- knife-edge device, 9- synchronizer, 10- workstation. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0017] Example 1 like Figure 1 As shown, the present invention proposes an aerodynamic structure measurement system for an extremely high-speed and high-enthalpy flow field environment, comprising a high-speed camera 1, an illumination light source 2, a light modulation 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; 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 with each other; 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 light source 2 are placed side by side at the focal position of the reflector 4 on the other side of the test section, and the light emitted by the illumination light source 2 passes through the light modulation device 3 and the reflector 4, and under the reflection of the reflector 4, passes through the two wind tunnel windows 5 and converges to the focal position of the reflector 4 again, and then passes through the knife-edge device 8 and is photographed by the high-speed camera 1; the light modulation device 3 is used to change the light emitted by the illumination light source 2 from a point light source to a vertical line light source; The narrow-band filter 7 is installed in front of the lens of the high-speed camera 1 to allow the light generated by the illumination light source 2 to pass through and filter out the self-luminescence of other flow fields; The high-speed camera 1 and the illumination light source 2 are connected via a synchronizer 9, so that the high-speed camera 1 and the illumination light source 2 can work at the same frequency; The workstation 10 is connected to the high-speed camera 1 and receives images taken by the high-speed camera 1 to perform analysis of the aerodynamic structure.

[0018] The internal parameters and communication protocol of the high-speed camera 1 and the lighting source 2 are set 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 a light-emitting state when the high-speed camera 1 is exposed, and the lighting source 2 is not emitting light when the high-speed camera 1 is not exposed.

[0019] Preferably, the shooting frequency of the high-speed camera 1 is not less than 10000fps, and the continuous exposure time is not higher than 1 / 100000s; the light emitting frequency of the illumination light source 2 is not lower than the shooting frequency of the high-speed camera 1, and the light emitting time is not higher than the camera exposure time.

[0020] The trigger port of the high-speed camera 1 is connected to the flow trigger signal of the wind tunnel through a cable, so that when the flow field is started, the high-speed camera 1 and the illumination light source 2 start working according to the set parameters.

[0021] The knife edge device 8 comprises 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 knife edge device 8 is not less than the width of the vertical light source.

[0022] The reflector 4 is a concave mirror, the focal length of the reflector 4 is greater than half of 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 .

[0023] The projection area of ​​the target model 6 on the wind tunnel window 5 is not greater than 1 / 2 of the area of ​​the wind tunnel window 5 .

[0024] The flow field velocity of the extremely high-speed and high-enthalpy flow field environment is above 2000 m / s, and the total temperature is above 6000K.

[0025] Based on the above-mentioned aerodynamic structure measurement system, this embodiment also proposes an aerodynamic structure measurement method for an extremely high-speed and high-enthalpy flow field environment, such as Figure 2 As shown, the following steps are included: S1. Determine the wavelength value of the illumination light source for the extremely high-speed and high-enthalpy flow field, and select the illumination light source 2 used in the aerodynamic structure measurement system.

[0026] Step S1 specifically includes: 110. Measure the spontaneous luminescence spectrum distribution of extremely high-speed and high-enthalpy flow fields; 120. Extracting a spectrum curve with a frequency range of 400 nm to 760 nm from the spontaneous luminescence spectrum distribution to obtain a flow field visible light spectrum intensity curve; 130. Check the single-wavelength laser products available in the market, check all existing laser wavelengths against the visible light spectrum intensity curve, obtain the spectrum relative intensity values ​​corresponding to all lasers, and select the laser with the smallest spectrum relative intensity value as the illumination light source 2 on the premise that the basic requirements of the laser are met. The basic requirements of the laser are: having the function of synchronizing with external equipment, and the synchronization frequency can reach above 10KHz.

[0027] S2. Acquire an aerodynamic structure image of an extremely high-speed and high-enthalpy flow field environment using the aerodynamic structure measurement system.

[0028] Step S2 specifically includes: 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 light source 2 side by side at the focal position of the reflector 4 on the other side of the test section.

[0029] 220 , the illumination light source 2 is turned on, and the light emitted by the light source passes through the light modulation device 3 and the reflector 4 , and is converged to the focal position of the reflector 4 , and then passes through the knife-edge device 8 to be photographed by the high-speed camera 1 .

[0030] 230. Adjust the distance between the illumination light source 2 and the reflector 4 so that the focus of the reflected light passes through the central slit of the knife-edge device 8.

[0031] 240. Parameter settings for high-speed camera 1 and lighting source 2. The shooting frequency of high-speed camera 1 shall not be less than 10,000 fps, and the continuous exposure time shall not be higher than 1 / 100,000 s. The light emission frequency of lighting source 2 shall not be lower than the shooting frequency of high-speed camera 1, and the light emission time shall not be higher than the camera exposure time.

[0032] 250. The high-speed camera 1 and the illumination light source 2 are set synchronously. The high-speed camera 1 and the illumination light source 2 are connected through the synchronizer 9, and the internal parameters and communication protocols of the two devices are set so that the high-speed camera 1 is the main synchronization device and the illumination light source 2 is the controlled device. The two devices work at the same frequency, and the illumination light source 2 is in the light-emitting state when the high-speed camera 1 is exposed, and the illumination light source 2 is not emitted when the high-speed camera 1 is not exposed.

[0033] 260. Install the narrowband filter 7 in front of the lens of the high-speed camera 1, and connect the wind tunnel 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 light source 2 start working according to the set parameters.

[0034] 270. The flow field is started, and the wind tunnel flow trigger signal triggers the high-speed camera 1 and the illumination light source 2 to work. The light source illuminates the wind tunnel flow field, and the high-speed camera 1 collects and obtains an image containing the aerodynamic structure. After the wind tunnel flow field ends, the aerodynamic structure image in the high-speed camera 1 is saved to the workstation 10 for aerodynamic structure analysis.

[0035] S3, filtering the aerodynamic structure image, detecting the shock wave boundary layer and the target model 6 in the filtered image, and obtaining the shock wave boundary layer contour and the model boundary contour.

[0036] Step S3 specifically includes: 310. Use the following function to filter the image, where is the pixel value after filtering at the image position (x, y), is the pixel value before filtering at the (x, y) position, is the filter window, is the mean value of all pixels in the filter window, is the image noise variance before filtering, is the pixel value variance within the filter window.

[0037]

[0038] Based on the Matlab development platform, the "edge" function and the "canny" operator are used to detect the shock wave boundary layer and the target model 6 in the filtered image to obtain the shock wave boundary layer contour and the model boundary contour.

[0039] S4. According to the model boundary contour, obtain the known length value of the target model 6 L (e.g. the length of the entire target model 6) The number of pixels occupied in the aerodynamic structure image pixel L , and then get the actual length value corresponding to a pixel .

[0040] S5, comparing the pixel position information of the model boundary contour and the shock wave boundary layer contour to obtain the pixel length of the detached shock wave at the target model stagnation point position, the pixel length of the target model spanwise boundary layer, and the pixel difference between the detached shock wave generation position and the target model stagnation point position, and respectively comparing the pixel length of the detached shock wave, the pixel length of the target model spanwise boundary layer, and the pixel difference with The values ​​are multiplied to obtain the detached shock wave distance, boundary layer thickness and separation shock wave position, which are used as the final output aerodynamic structure parameters.

[0041] The system and method proposed in the present invention can quantitatively analyze aerodynamic structure parameters, solving the problem that the prior art cannot measure aerodynamic structures in extremely high-speed and high-enthalpy flow fields.

[0042] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0043] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. An aerodynamic structure measurement system for extremely high-speed and high-enthalpy flow field environments, characterized in that: It includes a high-speed camera (1), an illumination light source (2), a light 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); 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 with each other; 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 light 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 light source (2) passes through the light modulation device (3) and the reflector (4), passes through the two wind tunnel windows (5) under the reflection action of the reflector (4), and is re-converged to the focal position of the reflector (4), and then passes through the knife-edge device (8) to be photographed by the high-speed camera (1); the light modulation device (3) is used to change the light emitted by the illumination light source (2) from a point light source to a vertical line light source; 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 light source (2) to pass through and filter out other self-luminous light from the flow field; The high-speed camera (1) and the illumination light source (2) are connected via a synchronizer (9) to achieve synchronous operation of the high-speed camera (1) and the illumination light source (2); The workstation (10) is connected to the high-speed camera (1) and receives images captured by the high-speed camera (1) to perform analysis of the aerodynamic structure.

2. The aerodynamic structure measurement system for extremely high-speed and high-enthalpy flow field environment according to claim 1, characterized in that: The internal parameters and communication protocol of the high-speed camera (1) and the illumination light source (2) are set so that the high-speed camera (1) is the main synchronization device and the illumination light source (2) is the controlled device, so that the high-speed camera (1) and the illumination light source (2) work at the same frequency, and the illumination light source (2) is in a light-emitting state when the high-speed camera (1) is exposing, and the illumination light source (2) is not emitting light when the high-speed camera (1) is not exposing.

3. The aerodynamic structure measurement system for extremely high-speed and high-enthalpy flow field environment according to claim 2, characterized in that: The parameter settings of the high-speed camera (1) and the illumination light source (2) include: the shooting frequency of the high-speed camera (1) is not less than 10000fps, and the continuous exposure time is not more than 1 / 100000s; the light emission frequency of the illumination light source (2) is not less than the shooting frequency of the high-speed camera (1), and the light emission time is not more than the camera exposure time.

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

5. The aerodynamic structure measurement system for extremely high-speed and high-enthalpy flow field environment according to claim 1, characterized in that: The knife edge device (8) comprises 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 knife edge device (8) is not less than the width of the vertical light source.

6. The aerodynamic structure measurement system for extremely high-speed and 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 extremely high-speed and high-enthalpy flow field environment according to claim 1, characterized in that: The projection area of ​​the target model (6) on 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 extremely high-speed and high-enthalpy flow field environment according to claim 1, characterized in that: The flow field velocity of the extremely high-speed and high-enthalpy flow field environment is above 2000 m / s, and the total temperature is above 6000K.

9. A method for measuring aerodynamic structures in an extremely high-speed and high-enthalpy flow field environment based on the system of claims 1 to 8, characterized in that: The following steps are involved: S1, determining the wavelength value of the illumination light source of the extremely high-speed and high-enthalpy flow field, and selecting the illumination light source (2) used by the aerodynamic structure measurement system; S2. Acquiring an aerodynamic structure image of an extremely high-speed and high-enthalpy flow field environment using the aerodynamic structure measurement system; S3, filtering the aerodynamic structure image, detecting the shock wave boundary layer and the target model (6) in the filtered image, and obtaining the shock wave boundary layer contour and the model boundary contour; S4. According to the model boundary contour, obtain the known length value of the target model (6) L The number of pixels in the aerodynamic structure image pixel L , and then get the actual length value corresponding to a pixel ; S5, comparing the pixel position information of the model boundary contour and the shock wave boundary layer contour to obtain the pixel length of the detached shock wave at the target model stagnation point position, the pixel length of the target model spanwise boundary layer, and the pixel difference between the detached shock wave generation position and the target model stagnation point position, and respectively comparing the pixel length of the detached shock wave, the pixel length of the target model spanwise boundary layer, and the pixel difference with The values ​​are multiplied to obtain the detached shock wave distance, boundary layer thickness and separation shock wave position, which are used as the final output aerodynamic structure parameters.

10. The method for measuring aerodynamic structures in an extremely high-speed and high-enthalpy flow field environment according to claim 9, characterized in that: The illumination light source (2) used in the aerodynamic structure measurement system is selected, comprising: Measure the spontaneous luminescence spectrum distribution of extremely high-speed and high-enthalpy flow fields; Extracting a spectrum curve with a frequency range of 400nm to 760nm from the spontaneous luminescence spectrum distribution to obtain a flow field visible light spectrum intensity curve; The wavelengths of all existing lasers are queried against the visible light spectrum intensity curve to obtain the spectrum relative intensity values ​​corresponding to all lasers. On the premise that the basic requirements of the laser are met, the laser with the smallest spectrum relative intensity value is selected as the illumination light source (2); the basic requirements of the laser are: having an external device synchronization function and a synchronization frequency of more than 10KHz.

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