A radiation spectrum measurement method for real-time tracking of the spatial position of the surface of heat-resistant materials

Abstract

The present invention discloses a radiation spectrum measurement method for real-time tracking of the spatial position of the surface of a heat protection material in the technical field of aerodynamic thermal protection of hypersonic aircraft, comprising the following steps: before the start of an experiment, calibrating the corresponding relationship between the axial spatial position of the surface of the heat protection material and the imaging position of the target surface of a spectrometer camera, so as to track the spatial position of the surface of the heat protection material in real time during ground experimental measurement; during the experiment, using a spectrometer to collect spectra in the axial space of the surface of the heat protection material; based on the calibrated corresponding relationship between the axial spatial position of the surface of the heat protection material and the imaging position of the target surface of the spectrometer camera, analyzing and processing the collected spectral image, so as to obtain the dynamic change law of the radiation spectrum of different axial spatial positions of the surface of the heat protection material in real time during aerodynamic heating.

Description

Technical Field

[0001] The present invention relates to the technical field of aerodynamic thermal protection for hypersonic vehicles, and in particular to a radiation spectrum measurement method for real-time tracking of the spatial position of a surface of a heat protection material. Background Art

[0002] During hypersonic flight, the surface of the aircraft thermal protection material is not only subjected to severe aerodynamic heating, but also there are gas-solid interface coupling effects such as catalysis, oxidation, and ablation between the high enthalpy non-equilibrium flow field in the boundary layer and the aircraft thermal protection material. The radiation characteristics of high-temperature gases in the boundary layer contain rich chemical reaction flow field information, which can be used to analyze the important reaction component information between the gas-solid interface and identify the main physical and chemical reaction paths based on the dynamic information of the radiation spectrum.

[0003] At present, experimental research on emission spectroscopy is mainly based on the assumption of static boundaries on the material surface during the experiment. M. Balat-Pichelin et al. (see paper: Passive / active oxidation transition for CMC structural materials designed for the IXV vehicle re-entry phase) inferred the gas-solid interface coupling effect based on the spatiotemporally resolved radiation information of oxygen and nitrogen atoms on the material surface and the characteristic ablation component Si atom information, and measured the relative intensity of the atomic emission spectrum based on the light energy intensity contrast method, and inferred the gradient distribution of the concentration of composite atoms on the surface of the heat-resistant material, and then calculated the catalytic composite situation on the surface of the heat-resistant material according to the diffusion equation.

[0004] However, in a long-duration service environment, the change in the spatial position of the heat-resistant material surface caused by the ablation of the heat-resistant material surface cannot be ignored. The heat flux density in the stagnation area is the highest, so the ablation in this area is also the most serious. The acquisition optical path of Balat et al. achieves the simultaneous measurement of the radiation intensity of points at different axial spatial positions on the surface of the heat-resistant material. However, the acquisition system does not move during the experiment. As the material surface expands or retreats, the spatial distance between the measurement point and the surface of the heat-resistant material is unknown, and there is a lack of real-time monitoring of the ablation deformation process of the material surface during the experiment.

[0005] To solve this problem, Yue Niu et al. (see paper: Emission spectroscopy diagnosis and discharge characteristics distribution analysis of high-frequency, high-enthalpy inductive coupling plasma generator) installed the spectral acquisition system on a movable track. This setup can achieve continuous measurement of the emission spectrum intensity in the axial position during the experiment, but this method loses the time resolution of the radiation acquisition spectrum.

[0006] In summary, the existing radiation spectrum measurement method cannot track the radiation spectrum at different axial spatial positions on the surface of the heat-resistant material under ablation deformation in real time, which is not conducive to analyzing the reaction component information between the gas-solid interface and predicting the complex physical and chemical processes between the gas-solid interface. Summary of the invention

[0007] The purpose of the present invention is to provide a radiation spectrum measurement method for real-time tracking of the spatial position of the surface of a heat-resistant material, so as to solve the technical problem that the radiation spectrum measurement method in the prior art cannot track the radiation spectrum at different axial spatial positions on the surface of the heat-resistant material under ablation deformation in real time, which is not conducive to analyzing the reaction component information between the gas-solid interface and predicting the complex physical and chemical processes between the gas-solid interface.

[0008] In order to solve the above technical problems, the present invention specifically provides a radiation spectrum measurement method for real-time tracking of the spatial position of the surface of a heat-resistant material, comprising the following steps:

[0009] Before the experiment begins, calibrate the correspondence between the axial spatial position of the heat protection material surface and the imaging position of the spectrometer camera target surface, so as to track the spatial position of the heat protection material surface in real time during the ground experiment measurement;

[0010] During the experiment, a spectrometer was used to collect spectra in the axial space on the surface of the heat protection material;

[0011] Based on the correspondence between the calibrated axial spatial position of the heat protection material surface and the imaging position of the spectrometer camera target, the collected spectral images are analyzed and processed to obtain the dynamic change law of the radiation spectrum of different axial spatial positions on the surface of the heat protection material in real time during aerodynamic heating.

[0012] As a preferred solution of the present invention, the corresponding relationship between the axial spatial position of the surface of the heat-resistant material and the imaging position of the target surface of the spectrometer camera is calibrated by a calibration system;

[0013] The calibration system includes a level, a horizontal displacement stage, a heat-proof material, a rectangular aperture, a cylindrical lens and a spectrometer;

[0014] The level is used to generate a horizontal laser parallel to the slit of the spectrometer;

[0015] The heat-proof material is fixed on the horizontal displacement stage and placed between the horizontal laser and the slit optical path of the spectrometer;

[0016] The rectangular aperture and the cylindrical lens are arranged on both sides of the spectrometer. The rectangular aperture is used to reduce light scattering and interference of stray light in the slit light path, and the cylindrical lens is used to focus the horizontal laser into a line laser in the vertical direction so that it passes through the slit of the spectrometer.

[0017] As a preferred solution of the present invention, a calibration method for the correspondence between the axial spatial position of the surface of the heat-resistant material and the imaging position of the target surface of the spectrometer camera comprises the following steps:

[0018] A horizontal laser is generated by a level meter parallel to the slit of the spectrometer. The radiation spectrum at this time is collected based on the imaging mode of the spectrometer. The slit size is 50 microns and the exposure time is 1000 microseconds.

[0019] Fix the heat protection material on the horizontal translation stage and place it between the horizontal laser and the slit optical path of the spectrometer;

[0020] Use a spectrometer to record the dynamic information of the imaging position of the spectrometer camera target surface in real time during the movement of the heat protection material model, and conduct multiple repeated experiments to eliminate measurement errors;

[0021] According to the dynamic information of the actual spatial position of the heat protection material model during movement and the imaging position of the spectrometer camera target surface, the correspondence between the actual spatial position of the heat protection material surface and the imaging position of the spectrometer camera target surface is calibrated to realize real-time tracking of the spatial position of the heat protection material surface during ground experimental measurement.

[0022] As a preferred solution of the present invention, a linear fitting based on the least squares method is performed on the actual spatial position of the material surface and the pixel position to obtain a fitting relationship between different pixel positions and the actual spatial position of the material surface, so as to obtain the actual spatial position of the surface of the heat-resistant material according to the imaging position of the camera target surface in experimental measurement.

[0023] As a preferred solution of the present invention, an inductively coupled plasma device or an arc-heated plasma device is used during the experiment to provide a flight-like experimental environment.

[0024] As a preferred solution of the present invention, the average change rate and real-time dynamic change rate of the spatial position of the material surface during the experiment can be quantified according to the corresponding relationship between the axial spatial position of the heat-resistant material surface and the imaging position of the spectrometer camera target surface, reflecting the linear ablation rate of the heat-resistant material;

[0025] The quantitative calculation formula is as follows:

[0026] The calculation formula for the average linear change rate of the spatial position of the surface of the heat protection material in the first t seconds is as follows:

[0027]

[0028] In the formula, is the average linear change in the previous t seconds (mm / s), y t is the spatial position of the material surface at the tth second (mm), y 0 is the spatial position of the material surface at the initial moment (mm);

[0029] The formula for calculating the real-time dynamic change rate of the spatial position of the surface of the heat-resistant material is as follows:

[0030]

[0031] In the formula, x t is the dynamic change at the t-th second (mm / s), Δy t is the relative displacement of the material surface at the tth second (mm), Δy t-Δt is the relative displacement of the material surface at t-Δt seconds (mm), and Δt is the interval between two adjacent images (s).

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention collects spectra at the axial space of the surface of the heat-resistant material based on a spectrometer with a planar array camera. Through the correspondence between the axial spatial position of the surface of the heat-resistant material calibrated before the experiment and the imaging position of the spectrometer camera target surface, real-time monitoring of each spatial position on the surface of the material during the ground experiment can be achieved. In this way, the radiation spectrum at different axial spatial positions on the surface of the heat-resistant material under ablation deformation can be tracked in real time, and its synchronous dynamic changes can be obtained, providing more accurate reference information for the analysis of chemical reactions on the surface of the heat-resistant material, which helps to more accurately predict the complex physical and chemical processes between the gas-solid interface.

[0034] Based on the images of the dynamic changes in the radiation spectrum of the heat-resistant material surface at different axial spatial positions in real time during the aerodynamic heating process, the expansion and ablation and regression process of the material during the aerodynamic heating process of the ground experiment can be intuitively seen, and the ablation performance of the heat-resistant material under certain conditions can be evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0036] Figure 1 is a schematic diagram of a calibration system in an embodiment of the present invention;

[0037] Figure 2 It is a sequence diagram of the spatial positions of the material surface collected by the spectrometer during the calibration process in the embodiment of the present invention;

[0038] Figure 3 A chart showing the positions of the pixels on the target surface of the spectrometer camera corresponding to the spatial positions of the material surface averaged after multiple calibration experiments in an embodiment of the present invention;

[0039] Figure 4 Schematic diagram of the fitting relationship between the actual spatial position of the material surface and the pixel position in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The present invention specifically provides a radiation spectrum measurement method for real-time tracking of the spatial position of the surface of a heat-resistant material, comprising the following steps:

[0042] Before the experiment begins, calibrate the correspondence between the axial spatial position of the heat protection material surface and the imaging position of the spectrometer camera target surface, so as to track the spatial position of the heat protection material surface in real time during the ground experiment measurement;

[0043] During the experiment, a spectrometer was used to collect spectra in the axial space on the surface of the heat protection material;

[0044] Based on the correspondence between the calibrated axial spatial position of the heat protection material surface and the imaging position of the spectrometer camera target, the collected spectral images are analyzed and processed to obtain the dynamic change law of the radiation spectrum of different axial spatial positions on the surface of the heat protection material in real time during aerodynamic heating.

[0045] The present invention collects spectra at the axial space of the surface of the heat-resistant material based on a spectrometer with a planar array camera. Through the correspondence between the axial spatial position of the surface of the heat-resistant material calibrated before the experiment and the imaging position of the spectrometer camera target surface, real-time monitoring of each spatial position on the surface of the material during the ground experiment can be achieved. In this way, the radiation spectrum at different axial spatial positions on the surface of the heat-resistant material under ablation deformation can be tracked in real time, and its synchronous dynamic changes can be obtained, providing more accurate reference information for the analysis of chemical reactions on the surface of the heat-resistant material, which helps to more accurately predict the complex physical and chemical processes between the gas-solid interface.

[0046] In addition, the images of the dynamic changes of the radiation spectrum of the surface of the heat-shielding material at different axial spatial positions in real time during the aerodynamic heating process can be obtained, which can intuitively show the expansion and ablation and regression process of the material during the aerodynamic heating process of the ground experiment, and can evaluate the ablation performance of the heat-shielding material under certain conditions. The average change rate and real-time dynamic change rate of the spatial position of the surface of the heat-shielding material can be quantified, providing key ablation and regression distance and ablation and regression rate parameters for the optimization and calibration of the prediction model of the ablation behavior of the heat-shielding material.

[0047] It should be noted that Figure 1 Two heat shields are shown in the figure. The heat shield on the horizontal translation stage is used for calibration, and the heat shield on the bracket is used for experiments. The two are of the same size to ensure that the calibration results can be directly used in experiments.

[0048] Furthermore, the present invention calibrates the corresponding relationship between the axial spatial position of the surface of the heat protection material and the imaging position of the target surface of the spectrometer camera through a calibration system;

[0049] The calibration system includes a level, a horizontal displacement stage, a heat-proof material, a rectangular aperture, a cylindrical lens and a spectrometer;

[0050] The level is used to generate a horizontal laser parallel to the slit of the spectrometer;

[0051] The heat protection material is fixed on the horizontal displacement stage and placed between the horizontal laser and the slit optical path of the spectrometer;

[0052] The rectangular aperture and the cylindrical lens are arranged on both sides of the spectrometer. The rectangular aperture is used to reduce light scattering and interference of stray light in the slit light path, and the cylindrical lens is used to focus the horizontal laser into a line laser in the vertical direction so that it passes through the slit of the spectrometer.

[0053] Furthermore, the calibration method of the correspondence between the axial spatial position of the surface of the heat-resistant material and the imaging position of the target surface of the spectrometer camera comprises the following steps:

[0054] A horizontal laser is generated by a level meter parallel to the slit of the spectrometer. The radiation spectrum at this time is collected based on the imaging mode of the spectrometer. The slit size is 50 microns and the exposure time is 1000 microseconds.

[0055] Fix the heat protection material on the horizontal translation stage and place it between the horizontal laser and the slit optical path of the spectrometer;

[0056] Use a spectrometer to record the dynamic information of the imaging position of the spectrometer camera target surface in real time during the movement of the heat protection material model, and conduct multiple repeated experiments to eliminate measurement errors;

[0057] According to the dynamic information of the actual spatial position of the heat protection material model during movement and the imaging position of the spectrometer camera target surface, the correspondence between the actual spatial position of the heat protection material surface and the imaging position of the spectrometer camera target surface is calibrated to realize real-time tracking of the spatial position of the heat protection material surface during ground experimental measurement.

[0058] Furthermore, the real-time recorded images of the surface of the heat-shielding material can clearly show the change process of the spatial position of the surface of the heat-shielding material, such as Figure 2 As shown, position 0 is the initial position of the material surface, position 1 is the position where the material surface retreats 1 mm, position 2 is the position where the material surface retreats 2 mm, and so on. The corresponding pixel positions of the spectrometer camera target surface are as follows: Figure 3 as shown in .

[0059] like Figure 4 As shown, the actual spatial position of the material surface and the pixel position are fitted by the least square method to obtain a fitting relationship between different pixel positions and the actual spatial position of the material surface, so as to obtain the actual spatial position of the heat-resistant material surface according to the imaging position of the camera target surface in the experimental measurement.

[0060] Furthermore, during the experiment, an inductively coupled plasma device or an arc-heated plasma device is used to provide an experimental environment similar to flight.

[0061] Furthermore, according to the corresponding relationship between the axial spatial position of the heat-resistant material surface and the imaging position of the spectrometer camera target surface, the average change rate and real-time dynamic change rate of the spatial position of the material surface during the experiment can be quantified to reflect the linear ablation rate of the heat-resistant material.

[0062] The quantitative calculation formula is as follows:

[0063] The calculation formula for the average linear change rate of the spatial position of the surface of the heat protection material in the first t seconds is as follows:

[0064]

[0065] In the formula, is the average linear change in the previous t seconds (mm / s), yt is the spatial position of the material surface at the tth second (mm), y 0 is the spatial position of the material surface at the initial moment (mm);

[0066] The formula for calculating the real-time dynamic change rate of the spatial position of the surface of the heat-resistant material is as follows:

[0067]

[0068] In the formula, x t is the dynamic change at the t-th second (mm / s), Δy t is the relative displacement of the material surface at the tth second (mm), Δy t-Δt is the relative displacement of the material surface at t-Δt seconds (mm), and Δt is the interval between two adjacent images (s).

[0069] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A radiation spectrum measurement method for real-time tracking of the spatial position of the surface of a heat-resistant material, characterized in that: The following steps are involved: Before the experiment begins, the calibration system is used to calibrate the correspondence between the axial spatial position of the surface of the heat protection material and the imaging position of the target surface of the spectrometer camera, so as to track the spatial position of the surface of the heat protection material in real time during the ground experiment measurement; During the experiment, a spectrometer was used to collect spectra in the axial space on the surface of the heat protection material; Based on the correspondence between the calibrated axial spatial position of the heat-resistant material surface and the imaging position of the spectrometer camera target surface, the collected spectral images are analyzed and processed to obtain the dynamic change law of the radiation spectrum of the heat-resistant material surface at different axial spatial positions in real time during the aerodynamic heating process. The calibration system includes a level, a horizontal displacement stage, a heat-resistant material, a rectangular aperture, a cylindrical lens, and a spectrometer; The level is used to generate a horizontal laser parallel to the slit of the spectrometer; The heat-proof material is fixed on the horizontal displacement stage and placed between the horizontal laser and the slit optical path of the spectrometer; The rectangular diaphragm and the cylindrical lens are arranged on both sides of the spectrometer, the rectangular diaphragm is used to reduce the light scattering and interference of stray light in the slit light path, and the cylindrical lens is used to focus the horizontal laser into a line laser in the vertical direction so that it passes through the slit of the spectrometer; The calibration method of the corresponding relationship between the axial spatial position of the surface of the heat-resistant material and the imaging position of the target surface of the spectrometer camera comprises the following steps: A horizontal laser is generated by a level meter parallel to the slit of the spectrometer. The radiation spectrum at this time is collected based on the imaging mode of the spectrometer. The slit size is 50 microns and the exposure time is 1000 microseconds. Fix the heat protection material on the horizontal translation stage and place it between the horizontal laser and the slit optical path of the spectrometer; Use a spectrometer to record the dynamic information of the imaging position of the spectrometer camera target surface in real time during the movement of the heat protection material model, and conduct multiple repeated experiments to eliminate measurement errors; According to the dynamic information of the actual spatial position of the heat protection material during its movement and the imaging position of the spectrometer camera target surface, the corresponding relationship between the actual spatial position of the heat protection material surface and the imaging position of the spectrometer camera target surface is calibrated to achieve real-time tracking of the spatial position of the heat protection material surface during ground experimental measurement; The actual spatial position of the material surface and the pixel position are fitted by the least square method to obtain the fitting relationship between different pixel positions and the actual spatial position of the material surface, so as to obtain the actual spatial position of the heat-resistant material surface according to the imaging position of the camera target surface in the experimental measurement; According to the corresponding relationship between the axial spatial position of the surface of the heat-resistant material and the imaging position of the spectrometer camera target surface, the average change rate and real-time dynamic change rate of the spatial position of the material surface during the experiment can be quantified to reflect the linear ablation rate of the heat-resistant material. The quantitative calculation formula is as follows: The calculation formula for the average linear change rate of the spatial position of the surface of the heat protection material in the first t seconds is as follows: In the formula, is the average line change in the previous t seconds, y t is the spatial position of the material surface at the tth second, and y0 is the spatial position of the material surface at the initial moment; The formula for calculating the real-time dynamic change rate of the spatial position of the surface of the heat-resistant material is as follows: In the formula, x t is the dynamic change at the t-th second, Δy t is the relative displacement of the material surface at the tth second, Δy t-Δt is the relative displacement of the material surface at t-Δt seconds, and Δt is the interval between two adjacent images.

2. The radiation spectrum measurement method for real-time tracking of the spatial position of the surface of a heat-resistant material according to claim 1 is characterized in that: During the experiment, an inductively coupled plasma device or an arc-heated plasma device is used to provide an experimental environment similar to flight.

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