Method and device for measuring parameters of high-enthalpy unbalanced flow field

Abstract

The embodiment of the invention provides a method and a device for measuring parameters of a high-enthalpy unbalanced flow field of an atomic oxygen and atomic nitrogen absorption spectrum, and the method comprises the steps: generating a high-enthalpy flow field at an outlet of a high-enthalpy wind tunnel nozzle, a laser absorption spectrum measurement system arranged in a high-enthalpy wind tunnel experiment section is used for carrying out synchronous measurement on the same to-be-measured flow field area of a high-enthalpy flow field, and the Gaussian half width and the integral absorption rate of an atomic nitrogen characteristic spectral line and the Gaussian half width and the integral absorption rate of an atomic oxygen characteristic spectral line are obtained; the effective absorption optical path of the laser penetrating through the high-enthalpy flow field and the pressure of the high-enthalpy flow field are obtained at the same time; setting an initial iteration value of the electron population temperature of the flow field, and based on the initial iteration value, adopting the constructed iteration algorithm to carry out iteration calculation until the temperature parameter converges to obtain a final electron population temperature; and according to the Gaussian half-width of the atomic nitrogen characteristic spectral line and the Gaussian half-width of the atomic oxygen characteristic spectral line, respectively obtaining the translational temperatures of the atomic nitrogen and the atomic oxygen.

Description

Technical Field

[0001] This document relates to the field of aerodynamic and thermal testing and measurement research on aircraft ground, and in particular to a method and apparatus for measuring high enthalpy nonequilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra. Background Technology

[0002] High-enthalpy wind tunnels, such as arc wind tunnels, high-frequency induction wind tunnels, and pulsed shock wave wind tunnels, are the main equipment for conducting thermal protection tests and assessments of hypersonic vehicles. During the reentry of a hypersonic vehicle into the atmosphere, the gas in the shock layer undergoes intense aerodynamic heating, resulting in complex thermochemical reactions such as dissociation and ionization, forming a high-temperature non-equilibrium flow field. Accurately measuring the concentration and temperature (translational temperature and electron population temperature) of key components (such as atomic nitrogen N and atomic oxygen O) in this flow field is crucial for verifying aerodynamic thermodynamic models and evaluating the performance of heat-resistant materials. When measuring atomic components (N, O), the traditional "dual-line thermometry" method requires selecting two spectral lines with different low energy levels and comparable absorption intensities for the same atom. However, in the near-infrared band, it is difficult to find a pair of biatomic spectral lines that meet the requirements, and to simultaneously measure the temperature of N and O, four lasers are often required, resulting in an extremely complex optical system and difficulties in optical path alignment. Existing single-line measurement methods can only perform single-temperature measurements that meet the thermal equilibrium assumption. They have limited applicability to non-equilibrium flow fields, and the measured temperatures often differ from the thermodynamic non-equilibrium state of the flow field. Furthermore, the particle number density obtained based on single-temperature measurements has a large deviation. Therefore, innovative measurement methods that can accurately decouple temperature and component concentration are needed to address the characteristics of high-enthalpy non-equilibrium flow fields. Summary of the Invention

[0003] The purpose of this invention is to provide a method and apparatus for measuring high enthalpy nonequilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra, aiming to solve the above-mentioned problems in the prior art.

[0004] This invention provides a method for measuring high-enthalpy non-equilibrium flow field parameters in the absorption spectra of atomic oxygen and atomic nitrogen, comprising: A high-enthalpy flow field is generated at the nozzle outlet of a high-enthalpy wind tunnel. A laser absorption spectroscopy measurement system arranged in the experimental section of the high-enthalpy wind tunnel is used to simultaneously measure the same test flow field region of the high-enthalpy flow field. The Gaussian half-width and integral absorptivity of the atomic nitrogen characteristic spectral line and the atomic oxygen characteristic spectral line are obtained. At the same time, the effective absorption optical path of the laser passing through the high-enthalpy flow field and the pressure of the high-enthalpy flow field are also obtained. Set an initial iterative value for the electron population temperature of the flow field. Based on the initial iterative value, use the constructed iterative algorithm to perform iterative calculations until the temperature parameters converge, and obtain the final electron population temperature. Based on the Gaussian half-width of the characteristic spectral lines of atomic nitrogen and atomic oxygen, the translational temperatures of atomic nitrogen and atomic oxygen were obtained, respectively.

[0005] This invention provides a device for measuring high-enthalpy non-equilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra, comprising: The acquisition module is used to generate a high-enthalpy flow field at the nozzle outlet of the high-enthalpy wind tunnel. A laser absorption spectroscopy measurement system arranged in the experimental section of the high-enthalpy wind tunnel is used to simultaneously measure the same test flow field region of the high-enthalpy flow field to obtain the Gaussian half-width and integral absorptivity of the atomic nitrogen characteristic spectral line, the Gaussian half-width and integral absorptivity of the atomic oxygen characteristic spectral line, and simultaneously obtain the effective absorption optical path of the laser passing through the high-enthalpy flow field and the pressure of the high-enthalpy flow field. The iteration module is used to set the initial iteration value of the electron population temperature of the flow field. Based on the initial iteration value, the constructed iterative algorithm is used to perform iterative calculations until the temperature parameters converge, and the final electron population temperature is obtained. The calculation module is used to obtain the translational temperatures of atomic nitrogen and atomic oxygen based on the Gaussian half-width of the characteristic spectral lines of atomic nitrogen and atomic oxygen, respectively.

[0006] This invention also provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, it implements the steps of the above-described method for measuring high enthalpy nonequilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra.

[0007] This invention also provides a computer-readable storage medium storing an information transmission implementation program, which, when executed by a processor, implements the steps of the above-described method for measuring high-enthalpy non-equilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra.

[0008] By employing embodiments of the present invention, based on the coupled measurement of atomic nitrogen and atomic oxygen, more accurate measurements of the non-equilibrium temperature and particle number density of high enthalpy flow fields can be achieved. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in one or more embodiments of this specification or in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a flowchart of a method for measuring high-enthalpy non-equilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra according to an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the relationship between component concentration and temperature T and pressure P obtained using the minimum Gibbs free energy method in an embodiment of the present invention. Figure 3 This is a schematic diagram of the high enthalpy non-equilibrium flow field parameter measuring device for atomic oxygen and atomic nitrogen absorption spectra according to an embodiment of the present invention; Figure 4 This is a schematic diagram of an electronic device according to an embodiment of the present invention; Figure 5 This is a detailed flowchart of the method for measuring high enthalpy non-equilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra according to an embodiment of the present invention. Detailed Implementation

[0011] To enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this document.

[0012] Method Implementation Examples According to embodiments of the present invention, a method for measuring high-enthalpy non-equilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra is provided. Figure 1 This is a flowchart of a method for measuring high-enthalpy non-equilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra according to an embodiment of the present invention. Figure 5 This is a detailed flowchart of the process for measuring high-enthalpy non-equilibrium flow field parameters in the absorption spectra of atomic oxygen and atomic nitrogen according to an embodiment of the present invention, as shown below. Figure 1 , 5 As shown, the method for measuring high-enthalpy non-equilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra according to an embodiment of the present invention specifically includes: Step S101: A high-enthalpy flow field is generated at the nozzle outlet of the high-enthalpy wind tunnel. A laser absorption spectroscopy measurement system arranged in the experimental section of the high-enthalpy wind tunnel is used to simultaneously measure the same test flow field region of the high-enthalpy flow field to obtain the Gaussian half-width and integral absorptivity of the atomic nitrogen characteristic spectral line, the Gaussian half-width and integral absorptivity of the atomic oxygen characteristic spectral line, and at the same time, the effective absorption optical path of the laser passing through the high-enthalpy flow field and the pressure of the high-enthalpy flow field are obtained. Step S102: Set the initial iteration value of the electron population temperature of the flow field. Based on the initial iteration value, use the constructed iterative algorithm to perform iterative calculations until the temperature parameters converge to obtain the final electron population temperature. The initial iterative value of the flow field electron population temperature is set according to Formula 4. : Formula 4; Where P represents the pressure in the high-enthalpy flow field. The integral absorbance of the characteristic spectral lines of atomic nitrogen. This represents the integrated absorbance of the characteristic spectral lines of atomic oxygen.

[0013] Step S102 specifically includes: Step 1, based on the electron population temperature of the current k-th iteration. Thermodynamic equilibrium and spectral calculations were performed to obtain the temperature of atomic nitrogen and atomic oxygen. Linear strength below and ; Step 2, based on the obtained line strength and Calculate the current absolute particle number density according to Formula 1: Formula 1; in, The integral absorbance of the characteristic spectral lines of atomic nitrogen. Let L be the integral absorbance of the characteristic spectral lines of atomic oxygen, and let L represent the effective absorption optical path length of the laser beam through the high-enthalpy flow field. This represents the current absolute particle number density of atomic nitrogen. This represents the current absolute particle number density of atomic oxygen; Step 3: Based on the calculated absolute particle number density, calculate the current atomic number density ratio based on spectral measurements using Formula 2: Formula 2; Step 4: Utilize the pre-established thermochemical correlation function of air components , Specifically: such as Figure 2 As shown, the relationship between component concentration and flow field temperature T and flow field pressure P was calculated using the minimum Gibbs free energy method. Here, T represents the flow field temperature, and P represents the flow field pressure. The flow field pressure P is obtained by measuring it through a wind tunnel wall pressure sensor, a Pitot tube, or calculating it based on the total pressure parameters of the wind tunnel operation and the nozzle expansion ratio. Under known pressure P, the method aims to find a value that produces an atomic number density ratio equal to... The corresponding equilibrium temperature is used as the temperature for the next iteration. That is, solving the equation ,in, Let represent the ratio of the absolute particle number density of atomic nitrogen to the absolute particle number density of atomic oxygen in the k-th iteration; solve the equation. Specifically, it includes: Solve the equation according to formula 3. : Formula 3; in, To meet temperature, The relaxation factor has a range of values ​​of 1000. .

[0014] Step 5: Calculate the temperature iteration residual. ;like If the value is less than the preset convergence threshold, the iteration stops. Labeled as the final measured population temperature Otherwise, let Return to step 1, wherein the preset convergence threshold ranges from [1, 10]. Step 6, based on the population temperature at final convergence Repeat step 2, formula 1, to calculate and output the absolute number density of atomic nitrogen in the flow field. The absolute particle number density of atomic oxygen .

[0015] Step S103: Based on the Gaussian half-width at half-maximum (WHM) of the characteristic spectral lines of atomic nitrogen and atomic oxygen, the translational temperatures of atomic nitrogen and atomic oxygen are obtained, respectively. Specifically, this includes: Calculate the translational temperature T of atomic nitrogen and atomic oxygen according to Formula 5. tr : Formula 5; in, Gaussian half-width, Let M be the center frequency and M be the molar mass.

[0016] The atomic nitrogen characteristic spectral lines are selected from transition lines within a predetermined range in the 868 nm band, and the atomic oxygen characteristic spectral lines are selected from transition lines within a predetermined range in the 777 nm band.

[0017] In summary, the embodiments of the present invention provide a method for measuring high enthalpy non-equilibrium flow field parameters based on atomic oxygen and atomic nitrogen absorption spectra. Based on the coupled measurement of atomic nitrogen and atomic oxygen, more accurate measurements of the non-equilibrium temperature and particle number density of high enthalpy flow fields can be achieved.

[0018] The advantages of this invention compared to the prior art are as follows: 1. The embodiments of the present invention combine atomic nitrogen and atomic oxygen coupled measurement to realize the quantitative determination of translational temperature, electron population temperature and N and O particle number density of non-equilibrium flow field, which can further quantitatively assess the degree of thermodynamic non-equilibrium of flow field.

[0019] 2. Through iterative calculation, the embodiments of the present invention can avoid the particle number density measurement error caused by single-temperature laser absorption spectroscopy measurement, and achieve accurate quantification of flow field parameters.

[0020] 3. The embodiments of the present invention can obtain flow field parameters simultaneously using two lasers (one N and one O), which simplifies the difficulty and cost of system integration.

[0021] Device Example 1 According to embodiments of the present invention, a device for measuring high-enthalpy non-equilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra is provided. Figure 3 This is a schematic diagram of the high-enthalpy non-equilibrium flow field parameter measuring device for atomic oxygen and atomic nitrogen absorption spectra according to an embodiment of the present invention, as shown below. Figure 3 As shown, the high-enthalpy non-equilibrium flow field parameter measuring device for atomic oxygen and atomic nitrogen absorption spectra according to an embodiment of the present invention specifically includes: The acquisition module 30 is used to generate a high-enthalpy flow field at the nozzle outlet of the high-enthalpy wind tunnel. A laser absorption spectroscopy measurement system arranged in the experimental section of the high-enthalpy wind tunnel is used to perform synchronous measurements on the same test flow field region of the high-enthalpy flow field to obtain the Gaussian half-width and integral absorptivity of the atomic nitrogen characteristic spectral line, the Gaussian half-width and integral absorptivity of the atomic oxygen characteristic spectral line, and simultaneously obtain the effective absorption optical path of the laser passing through the high-enthalpy flow field and the pressure of the high-enthalpy flow field. The iteration module 32 is used to set the initial iteration value of the electron population temperature of the flow field, and based on the initial iteration value, the constructed iterative algorithm is used to perform iterative calculations until the temperature parameters converge to obtain the final electron population temperature. The calculation module 24 is used to obtain the translational temperatures of atomic nitrogen and atomic oxygen based on the Gaussian half-width of the characteristic spectral lines of atomic nitrogen and atomic oxygen, respectively.

[0022] The embodiments of the present invention are device embodiments corresponding to the above method embodiments. The specific operation of each module can be understood with reference to the description of the method embodiments, and will not be repeated here.

[0023] Device Example 2 This invention provides an electronic device, such as... Figure 4 As shown, it includes: a memory 40, a processor 42, and a computer program stored in the memory 40 and executable on the processor 42, wherein the computer program, when executed by the processor 42, performs the steps as described in the method embodiment.

[0024] Device Example 3 This invention provides a computer-readable storage medium storing an information transmission implementation program, which, when executed by a processor 42, performs the steps described in the method embodiment.

[0025] The computer-readable storage media described in this embodiment include, but are not limited to, ROM, RAM, disk, or optical disk.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring high-enthalpy non-equilibrium flow field parameters in the absorption spectra of atomic oxygen and atomic nitrogen, characterized in that, include: A high-enthalpy flow field is generated at the nozzle outlet of a high-enthalpy wind tunnel. A laser absorption spectroscopy measurement system arranged in the experimental section of the high-enthalpy wind tunnel is used to simultaneously measure the same test flow field region of the high-enthalpy flow field. The Gaussian half-width and integral absorptivity of the atomic nitrogen characteristic spectral line and the atomic oxygen characteristic spectral line are obtained. At the same time, the effective absorption optical path of the laser passing through the high-enthalpy flow field and the pressure of the high-enthalpy flow field are also obtained. Set an initial iterative value for the electron population temperature of the flow field. Based on the initial iterative value, use the constructed iterative algorithm to perform iterative calculations until the temperature parameters converge, and obtain the final electron population temperature. Based on the Gaussian half-width of the characteristic spectral lines of atomic nitrogen and atomic oxygen, the translational temperatures of atomic nitrogen and atomic oxygen were obtained, respectively.

2. The method according to claim 1, characterized in that, Setting an initial iterative value for the electron population temperature of the flow field, and based on the initial iterative value, using the constructed iterative algorithm to perform iterative calculations until the temperature parameters converge, to obtain the final electron population temperature specifically includes: Step 1, based on the electron population temperature of the current k-th iteration. Thermodynamic equilibrium and spectral calculations were performed to obtain the temperature of atomic nitrogen and atomic oxygen. Linear strength below and ; Step 2, based on the obtained line strength and Calculate the current absolute particle number density according to Formula 1: Official 1; in, The integral absorbance of the characteristic spectral lines of atomic nitrogen. Let L be the integral absorbance of the characteristic spectral lines of atomic oxygen, and let L represent the effective absorption optical path length of the laser beam through the high-enthalpy flow field. This represents the current absolute particle number density of atomic nitrogen. This represents the current absolute particle number density of atomic oxygen; Step 3: Based on the calculated absolute particle number density, calculate the current atomic number density ratio based on spectral measurements using Formula 2: Official 2; Step 4: Utilize the pre-established thermochemical correlation function of air components Where T represents the flow field temperature and P represents the flow field pressure, the flow field pressure P is obtained by measuring it through a wind tunnel wall pressure sensor or a Pitot tube, or by calculating it based on the total pressure parameters of the wind tunnel operation and the nozzle expansion ratio. Under the condition of known pressure P, the goal is to find a system that can produce an atomic number density ratio equal to... The corresponding temperature is used as the temperature for the next iteration. That is, solving the equation ,in, This represents the ratio of the absolute particle number density of atomic nitrogen to the absolute particle number density of atomic oxygen in the k-th iteration. Step 5: Calculate the temperature iteration residual. ;like If the value is less than the preset convergence threshold, the iteration stops. Labeled as the final measured population temperature Otherwise, let Return to step 1, wherein the preset convergence threshold ranges from [1, 10]. Step 6, based on the population temperature at final convergence Repeat step 2, formula 1, to calculate and output the absolute number density of atomic nitrogen in the flow field. The absolute particle number density of atomic oxygen .

3. The method according to claim 2, characterized in that, Air component thermochemical correlation function Specifically, the relationship between component concentration and flow field temperature T and flow field pressure P was calculated using the minimum Gibbs free energy method.

4. The method according to claim 2, characterized in that, Solve the equation Specifically, it includes: Solve the equation according to formula 3. : Official 3; in, To meet temperature, The relaxation factor has a range of values ​​of 1000. .

5. The method according to claim 1, characterized in that, Setting the initial iterative value for the flow field electron population temperature specifically includes: The initial iterative value of the electron population temperature of the flow field is set according to Formula 4. : Official 4; Where P represents the pressure in the high-enthalpy flow field. The integral absorbance of the characteristic spectral lines of atomic nitrogen. This represents the integrated absorbance of the characteristic spectral lines of atomic oxygen.

6. The method according to claim 1, characterized in that, Based on the Gaussian half-width of the characteristic spectral lines of atomic nitrogen and atomic oxygen, the translational temperatures of atomic nitrogen and atomic oxygen are obtained, respectively, including: Calculate the translational temperature T of atomic nitrogen and atomic oxygen according to Formula 5. tr : Official 5; in, Gaussian half-width, Let M be the center frequency and M be the molar mass.

7. The method according to claim 1, characterized in that, The atomic nitrogen characteristic spectral lines are selected from transition lines within a predetermined range in the 868 nm band, and the atomic oxygen characteristic spectral lines are selected from transition lines within a predetermined range in the 777 nm band.

8. A device for measuring high-enthalpy non-equilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra, characterized in that, include: The acquisition module is used to generate a high-enthalpy flow field at the nozzle outlet of the high-enthalpy wind tunnel. A laser absorption spectroscopy measurement system arranged in the experimental section of the high-enthalpy wind tunnel is used to simultaneously measure the same test flow field region of the high-enthalpy flow field to obtain the Gaussian half-width and integral absorptivity of the atomic nitrogen characteristic spectral line, the Gaussian half-width and integral absorptivity of the atomic oxygen characteristic spectral line, and simultaneously obtain the effective absorption optical path of the laser passing through the high-enthalpy flow field and the pressure of the high-enthalpy flow field. The iteration module is used to set the initial iteration value of the electron population temperature of the flow field. Based on the initial iteration value, the constructed iterative algorithm is used to perform iterative calculations until the temperature parameters converge, and the final electron population temperature is obtained. The calculation module is used to obtain the translational temperatures of atomic nitrogen and atomic oxygen based on the Gaussian half-width of the characteristic spectral lines of atomic nitrogen and atomic oxygen, respectively.

9. An electronic device, characterized in that, include: The memory, the processor, and the computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the method for measuring high enthalpy nonequilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores an information transmission implementation program, which, when executed by a processor, implements the steps of the method for measuring high enthalpy non-equilibrium flow field parameters of atomic oxygen and atomic nitrogen absorption spectra as described in any one of claims 1 to 7.

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