A device and method for total temperature measurement in high-enthalpy shock tunnels

Abstract

The present application belongs to the technical field of wind tunnel test, and discloses a total temperature measuring device and method suitable for high-enthalpy shock tunnel. The signal generator, laser controller and laser of the measuring device are sequentially connected through cables. The laser light emitted by the laser passes through the emission end mirror, the shock boundary layer, the filter, the receiving end mirror and the beam diffusion negative lens in sequence, and then enters the photoelectric detector. The photoelectric detector is sequentially connected to the data acquisition system and the data analysis system through cables. The measuring method comprises the following steps: building the measuring device; debugging the laser light path; conducting high-enthalpy shock tunnel test; and conducting data analysis. The measuring device and method are placed in the test section, the semi-cylindrical model stagnation flow is used, the isentropic stagnation principle is used, the temperature after the shock wave of the semi-cylindrical leading edge is measured, and the total temperature of the flow field is indirectly measured. The measuring error caused by high pressure is reduced, the measuring precision is improved, and the measuring device has engineering practical value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wind tunnel test, and particularly relates to a total temperature measuring device and method suitable for high-enthalpy shock tunnel. BACKGROUND

[0002] The shock tunnel uses a moving shock wave to heat and pressurize test gas, and uses a high-speed gas flow formed by a nozzle to form a test condition. The shock tunnel has strong simulation capability and is a main equipment for high-Mach hypersonic combustion research. For super-combustion engine test, the test gas is air, the total temperature of the flow field reaches 3000K or above, the total pressure reaches tens of megapascals, and the test time is in the order of milliseconds. For temperature measurement in the high-temperature and low-pressure environment of the shock tunnel, tunable diode laser absorption spectroscopy (TDLAS) has strong adaptability. However, most of the current TDLAS temperature measurement researches measure a range below 3000K, and under high pressure, the adjacent spectral lines of TDLAS are severely overlapped, the linear temperature dependence is weakened, and the measurement accuracy is reduced.

[0003] At present, it is urgent to develop a total temperature measuring device and method suitable for high-enthalpy shock tunnel. SUMMARY

[0004] One of the technical problems to be solved by the application is to provide a total temperature measuring device suitable for high-enthalpy shock tunnel, and another technical problem to be solved by the application is to provide a total temperature measuring method suitable for high-enthalpy shock tunnel, so as to overcome the defects of the prior art.

[0005] The total temperature measuring device suitable for high-enthalpy shock tunnel is installed in the high-enthalpy shock tunnel; the high-enthalpy shock tunnel comprises a high-pressure section, a low-pressure section, a nozzle and a test section connected in sequence from front to back, and a diaphragm is arranged between the high-pressure section and the low-pressure section;

[0006] The trigger sensor of the measuring device is installed at a position close to the diaphragm in the low-pressure section;

[0007] The signal generator, the laser controller, the data acquisition system and the data analysis system of the measuring device are placed outside the test section; the laser and the emission end mirror are placed on the left side in the test section, a baffle is installed on the test inflow side of the laser, and a light-out hole is opened on the corresponding baffle for laser light to pass out; the optical filter, the beam diffusion negative lens, the receiving end mirror and the photodetector are placed on the right side in the test section, a baffle is also installed on the test inflow side of the photodetector, and a light-in hole is opened on the corresponding baffle for laser light to pass in, and the optical filter is covered on the light-in hole;

[0008] A semi-cylindrical model is installed in the core flow region of the test section. The axis of the semi-cylindrical model is parallel to the laser beam, and the elevation of the axis of the semi-cylindrical model is the same as that of the laser beam. A high-frequency pressure sensor is installed at the leading edge apex of the semi-cylindrical model. The hypersonic airflow in the high-enthalpy shock tunnel is heated and pressurized twice by the shock wave in the low-pressure section to form a high total temperature and total pressure gas. It is then accelerated through the nozzle and flows towards the test section. When it flows through the semi-cylindrical model, a standing shock wave is formed at the leading edge of the semi-cylindrical model. The standing shock wave is a detached shock wave. The space between the leading edge of the semi-cylindrical model and the standing shock wave is the shock wave boundary layer. The laser beam passes through the shock wave boundary layer from left to right.

[0009] The signal generator, laser controller, and laser are connected sequentially via cables. The laser beam emitted by the laser is reflected by the transmitting end mirror, passes through the shock boundary layer, and then passes through the filter, the receiving end mirror, and the beam diffusion negative lens in sequence before entering the photodetector. The photodetector is connected sequentially to the data acquisition system and the data analysis system via cables. The laser controller enters the test section through a sealed cable, and the photodetector exits the test section through a sealed cable.

[0010] Furthermore, the signal generator outputs a sawtooth wave with a frequency of 10kHz to the laser controller;

[0011] The laser is a NO laser with a center wavelength of 5288.7 nm;

[0012] The baffle is used to prevent diaphragm debris in the hypersonic airflow from hitting the laser and photodetector. The inner diameter of the light outlet is 20mm.

[0013] The frequency response of the high-frequency pressure sensor is not less than 100kHz;

[0014] The radius R of the semi-cylindrical model N The length L of the semi-cylindrical model is 100mm; the length L is the optical path of the laser beam, and the length L is not less than 500mm; the surface roughness of the semi-cylindrical model is better than 0.8μm.

[0015] Filters are used to reduce interference from background light, including burning flames, and to improve the signal-to-noise ratio of laser beams.

[0016] A beam-diffusing negative lens reduces optical power density by expanding the laser beam, protecting the photodetector and suppressing background noise.

[0017] The data acquisition system has a sampling frequency of 20MHz and a data retention time of 500 milliseconds.

[0018] Furthermore, the formula for calculating the thickness δ of the standing shock wave is as follows:

[0019] ;

[0020] in,M The Mach number of the incoming flow;

[0021] Nozzle stagnation chamber temperature T The absorbance is a function of the integral absorbance of each absorption peak, and the nozzle stagnation chamber temperature is... T The calculation formula is as follows:

[0022] ;

[0023] in, The integral absorbance of the first absorption peak. The integral absorbance of the second absorption peak; The energy difference between lower energy levels is expressed in cm. -1 ; The energy of the lower level before the transition to the first absorption peak, in cm⁻¹. -1 ; The energy of the lower level before the transition of the second absorption peak is expressed in cm⁻¹. -1 ; Reference temperature T r The line intensity of the absorption spectral line at the center frequency of the first absorption peak. T r Take 296K, unit: cm -2 / atm; Reference temperature T r The line intensity of the absorption spectral line at the center frequency of the second absorption peak, in cm. -2 / atm; h is Planck's constant, in J / s; c Speed ​​of light, measured in cm / s; k Boltzmann constant, in J / K;

[0024] Absorption line intensity The general calculation formula is as follows:

[0025] ;

[0026] in, E The energy of the low transition state is expressed in cm⁻¹. -1 ; Reference temperature T r Partition function; The gas molecule partition function. It is the nozzle stagnation chamber temperature. T The only function, Polynomial fitting is used:

[0027] ;

[0028] wherein, Z is the partition function of gas molecules The fitting coefficients of the post-shock NO gas are obtained by querying the HITRAN spectral database or directly calculated by the HITRAN software JavaHAWKS;

[0029] Molar concentration of post-shock NO X The calculation formula is as follows:

[0030] ;

[0031] wherein, P is the post-shock NO gas pressure, unit atm.

[0032] The total temperature measurement method suitable for high-enthalpy shock tunnel of the application comprises the following steps:

[0033] S10. Build a total temperature measurement device suitable for high-enthalpy shock tunnel;

[0034] S20. Debug the laser light path;

[0035] Switch the laser to a visible red light source to preliminarily adjust the laser light path; then, switch the laser to a laser waveband, connect the output signal of the oscilloscope to the photoelectric detector, monitor the sawtooth wave output by the signal generator to the laser controller, and accurately adjust the laser light path;

[0036] S30. Perform high-enthalpy shock tunnel test;

[0037] The high-enthalpy shock tunnel is filled with gas of preset pressure and temperature in the high-pressure section and the low-pressure section; after reaching the pre-set pressure and temperature conditions, the diaphragm between the high-pressure section and the low-pressure section breaks, forming a shock wave; the shock wave passes through the trigger sensor, the trigger sensor emits a trigger signal to the data acquisition system, and the data acquisition system starts to collect and save 500 milliseconds of data; at the same time, the trigger sensor emits a trigger signal to the laser controller, the laser controller controls the laser by adjusting the temperature and current, and the laser light output by the laser passes through the emission end mirror, the shock boundary layer, the optical filter, the receiving end mirror and the beam expansion negative lens in turn, and then enters the photoelectric detector through the optical fiber, the photoelectric detector converts the optical signal of the laser light into an electrical signal, and the electrical signal enters the data acquisition system for collection;

[0038] S40. Data analysis;

[0039] The data analysis system carries out electric signal processing to obtain a TDLAS test result curve graph, the curve graph shows that the NO laser with the center wavelength of 5288.7 nm has three absorption peaks, corresponding to three absorption spectrum lines near the wavelength of 5288.7 nm, three groups of temperature data are inverted by calculating the integral absorbance ratio of the absorption peaks combined in pairs, and finally the total temperature of the flow field is obtained.

[0040] The total temperature measuring device and method suitable for high-enthalpy shock tunnel of the application utilize three absorption peaks of a single NO laser at high temperature, three groups of temperature data are inverted by combining the three absorption peaks in pairs, millisecond-level, temperature 3000K and above are measured, the total temperature of the test section is indirectly measured by measuring the temperature in the shock boundary layer of the semi-cylindrical model in the test section, the pressure in the shock boundary layer is usually tens of kilopascals, belonging to low pressure, the measurement error caused by high pressure is reduced, the measurement accuracy and the upper limit of TDLAS temperature measurement are improved, and the NO concentration can also be inverted by using a high-frequency pressure sensor.

[0041] Briefly, the total temperature measuring device and method suitable for high-enthalpy shock tunnel of the application are placed in the test section, the airflow is stagnated by using a semi-cylindrical model, the total temperature of the flow field is indirectly measured by measuring the temperature after the shock wave in front of the semi-cylindrical model according to the isentropic stagnation principle, the total temperature measuring device and method suitable for high-enthalpy shock tunnel of the application have high frequency response characteristics, the measurement accuracy is improved by low pressure measurement, are suitable for high-enthalpy shock tunnel transient flow field total temperature measurement, and have engineering practical value. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 Fig. 1 is a structural schematic view (top view) of the total temperature measuring device suitable for high-enthalpy shock tunnel of the application;

[0043] Figure 2 Fig. 2 is a TDLAS test result curve graph obtained by an embodiment.

[0044] In the figure, 1. high pressure section; 2. trigger sensor; 3. low pressure section; 4. nozzle; 5. test section; 6. signal generator; 7. laser controller; 8. laser; 9. baffle; 10. transmitting end mirror; 11. shock boundary layer; 12. high-frequency pressure sensor; 13. semi-cylindrical model; 14. optical filter; 15. beam diffusion negative lens; 16. receiving end mirror; 17. photodetector; 18. data acquisition system; 19. data analysis system. DETAILED DESCRIPTION

[0045] The application will be described in detail below in combination with the drawings and embodiments.

[0046] Embodiment: The total temperature measuring device for high enthalpy shock tunnel is installed in the high enthalpy shock tunnel; the high enthalpy shock tunnel comprises a high pressure section 1, a low pressure section 3, a nozzle 4 and a test section 5 connected in sequence from front to back, and a diaphragm is arranged between the high pressure section 1 and the low pressure section 3;

[0047] The trigger sensor 2 of the measuring device is installed at a position close to the diaphragm in the low pressure section 3;

[0048] The signal generator 6, the laser controller 7, the data acquisition system 18 and the data analysis system 19 of the measuring device are placed outside the test section 5; the laser 8 and the transmitting end mirror 10 are placed on the left side in the test section 5, the baffle 9 is installed on the test flow side of the laser 8, and the light hole is opened on the corresponding baffle 9 for the laser light to pass out; the optical filter 14, the beam diffusion negative lens 15, the receiving end mirror 16 and the photodetector 17 are placed on the right side in the test section 5, the baffle 9 is also installed on the test flow side of the photodetector 17, and the light hole is opened on the corresponding baffle 9 for the laser light to pass in, and the optical filter 14 is covered on the light hole;

[0049] The semi-cylindrical model 13 is installed in the core flow area of the test section 5, the axis of the semi-cylindrical model 13 is parallel to the laser light, and the axis of the semi-cylindrical model 13 is at the same height as the laser light, and the high-frequency pressure sensor 12 is installed on the vertex of the leading edge of the semi-cylindrical model 13; the hypersonic airflow of the high enthalpy shock tunnel is heated and pressurized twice by the shock wave in the low pressure section 3 to form high total temperature and total pressure gas, and then accelerated to the test section 5 through the nozzle 4, and when flowing through the semi-cylindrical model 13, a standing wave is formed on the leading edge of the semi-cylindrical model 13, which is a detached shock wave, and the space between the leading edge of the semi-cylindrical model 13 and the standing wave is the shock wave boundary layer 11; the laser light passes through the shock wave boundary layer 11 from left to right;

[0050] The signal generator 6, the laser controller 7 and the laser 8 are connected in sequence through cables, the laser light emitted by the laser 8 is reflected by the transmitting end mirror 10, passes through the shock wave boundary layer 11, and then enters the photodetector 17 through the optical filter 14, the receiving end mirror 16 and the beam diffusion negative lens 15 in sequence, and the photodetector 17 is connected to the data acquisition system 18 and the data analysis system 19 through cables in sequence; the laser controller 7 is sealed into the test section 5 through cables, and the photodetector 17 is sealed out of the test section 5 through cables.

[0051] Further, the signal generator 6 outputs a sawtooth wave with a frequency of 10 kHz to the laser controller 7, which meets the millisecond-level measurement requirements of the high enthalpy shock tunnel;

[0052] Laser 8 is an NO laser with a center wavelength of 5288.7nm. At around 2000K, O2 molecules in the air begin to dissociate into O; at around 4000K, N2 in the air begins to dissociate into N. N combines with O to form NO. Using an NO laser allows for the measurement of effective signals at high temperatures.

[0053] The baffle 9 is used to prevent diaphragm debris in the hypersonic airflow from hitting the laser 8 and the photodetector 17. The inner diameter of the light outlet is 20mm.

[0054] The frequency response of the high-frequency pressure sensor 12 is not less than 100kHz;

[0055] The radius R of the semi-cylindrical model 13 N The length L of the semi-cylindrical model 13 is 100mm; the length L is the optical path of the laser beam, and the length L is not less than 500mm; the surface roughness of the semi-cylindrical model 13 is better than 0.8μm;

[0056] Filter 14 is used to reduce interference from background light, including burning flames, and improve the signal-to-noise ratio of the laser beam.

[0057] The beam-diffusing negative lens 15 reduces the optical power density by expanding the laser beam, protects the photodetector 17, and suppresses background noise.

[0058] The data acquisition system 18 has a sampling frequency of 20MHz and a storage time of 500 milliseconds.

[0059] Furthermore, the pressure and temperature behind the standing shock wave are significantly increased. Near the leading edge apex of the semi-cylindrical model 13, the airflow velocity behind the standing shock wave is almost stagnant to zero. According to the isentropic stagnation principle, the temperature behind the standing shock wave is the total temperature of the nozzle stagnation chamber of the high enthalpy shock wind tunnel. The pressure behind the standing shock wave is on the order of tens of kilopascals, which is several orders of magnitude lower than the pressure in the nozzle stagnation chamber. The pressure behind the standing shock wave is low pressure.

[0060] The formula for calculating the thickness δ of the standing shock wave is as follows:

[0061] ;

[0062] in, M The Mach number of the incoming flow;

[0063] Under low pressure, the broadening of the NO absorption spectrum is mainly Doppler broadening, and the integrated absorbance of each absorption peak satisfies the Boltzmann distribution. Temperature measurement is achieved by eliminating pressure and concentration through ratio.

[0064] Nozzle stagnation chamber temperature T The absorbance is a function of the integral absorbance of each absorption peak, and the nozzle stagnation chamber temperature is... T The calculation formula is as follows:

[0065] ;

[0066] wherein, is the first absorption peak integrated absorbance, is the second absorption peak integrated absorbance; is the low energy level energy difference, in cm -1 ; is the first absorption peak pre-transition low energy level energy, in cm -1 ; is the second absorption peak pre-transition low energy level energy, in cm -1 ; is the reference temperature T r is the absorption spectral line intensity at the first absorption peak center frequency, in cm T r at 296 K -2 / atm; is the reference temperature T r is the absorption spectral line intensity at the second absorption peak center frequency, in cm -2 / atm; h is the Planck constant, in J s; c is the speed of light, in cm / s; k is the Boltzmann constant, in J / K;

[0067] is the absorption spectral line intensity The general formula for calculating the absorption spectral line intensity is as follows:

[0068] ;

[0069] wherein, E is the low energy level energy, in cm -1 ; is the reference temperature T r is the partition function; is the gas molecule partition function, the gas molecule partition function is the only function of the nozzle chamber temperature T , which is fitted using a polynomial:

[0070] ;

[0071] wherein, is the gas molecule partition function ​coefficients are different for different gases and temperature ranges; the fitting coefficients of the NO gas after the shock wave are obtained by querying the HITRAN spectral database or directly calculated by the HITRAN software JavaHAWKS;

[0072] The calculation formula of the NO molar concentration after the shock wave is as follows: X

[0073] ;

[0074] Wherein, P is the NO gas pressure after the shock wave, unit: atm.

[0075] The total temperature measurement method suitable for high-enthalpy shock tunnel of the embodiment comprises the following steps:

[0076] S10. As shown in the figure, a total temperature measurement device suitable for high-enthalpy shock tunnel is built; Figure 1

[0077] S20. Adjust the laser light path;

[0078] Switch the laser 8 to a visible red light source to preliminarily adjust the laser light path; then, switch the laser 8 to a laser wave band, connect the output signal of the photoelectric detector 17 to the oscilloscope, monitor the sawtooth wave output by the signal generator 6 to the laser controller 7, and accurately adjust the laser light path;

[0079] S30. Perform high-enthalpy shock tunnel test;

[0080] The high-enthalpy shock tunnel is filled with gas of preset pressure and temperature in the high-pressure section 1 and the low-pressure section 3; after reaching the preset pressure and temperature conditions, the diaphragm between the high-pressure section 1 and the low-pressure section 3 is broken, forming a shock wave; the shock wave passes through the trigger sensor 2, the trigger sensor 2 emits a trigger signal to the data acquisition system 18, and the data acquisition system 18 starts to collect and save 500 milliseconds of data; at the same time, the trigger sensor 2 emits a trigger signal to the laser controller 7, the laser controller 7 controls the laser 8 by adjusting the temperature and current, and the light signal of the laser light emitted by the laser 8 passes through the emission end mirror 10, the shock boundary layer 11, the optical filter 14, the receiving end mirror 16 and the beam expansion negative lens 15 in turn, and then enters the photoelectric detector 17 through the optical fiber, the photoelectric detector 17 converts the light signal of the laser light into an electric signal, and the electric signal enters the data acquisition system 18 for collection;

[0081] S40. Perform data analysis;

[0082] The data analysis system 19 processes the electric signal to obtain the total temperature of the high-enthalpy shock tunnel as shown in the figure. Figure 2 ​​The TDLAS test result curve shown in the figure shows that the NO laser with a center wavelength of 5288.7 nm has three absorption peaks, corresponding to three absorption spectral lines near 5288.7 nm. By calculating the integral absorbance ratio of the two combined absorption peaks, three sets of temperature data are obtained, and finally the total temperature of the flow field is about 3600K.

[0083] Although embodiments of the present application have been disclosed as above, they are not limited to the use listed in the specification and embodiments, and all features disclosed in the present application, or steps in all methods or processes disclosed in the present application, can be combined in any way, except for mutually exclusive features and / or steps, without departing from the principles of the present application. The present application is not limited to specific details and figures shown and described herein.

Claims

1. A device for total temperature measurement in high-enthalpy shock tunnels, characterized in that, The measuring device is installed in the high-enthalpy shock tunnel; the high-enthalpy shock tunnel comprises a high-pressure section (1), a low-pressure section (3), a nozzle (4) and a test section (5) connected in sequence from front to back, and a diaphragm is arranged between the high-pressure section (1) and the low-pressure section (3); The trigger sensor (2) of the measuring device is installed at a position close to the diaphragm in the low-pressure section (3); The signal generator (6), the laser controller (7), the data acquisition system (18) and the data analysis system (19) of the measuring device are placed outside the test section (5); the laser (8) and the transmitting end mirror (10) are placed on the left side in the test section (5), the baffle (9) is installed on the test inflow side of the laser (8), and the corresponding baffle (9) is provided with an out-light hole for the laser light to pass out; the optical filter (14), the beam diffusion negative lens (15), the receiving end mirror (16) and the photoelectric detector (17) are placed on the right side in the test section (5), and the baffle (9) is also installed on the test inflow side of the photoelectric detector (17), and the corresponding baffle (9) is provided with an in-light hole for the laser light to pass in, and the in-light hole is covered with the optical filter (14); The semi-cylindrical model (13) is installed in the core flow area of the test section (5), the axis of the semi-cylindrical model (13) is parallel to the laser light, and the axis of the semi-cylindrical model (13) is at the same height as the laser light, and the vertex of the leading edge of the semi-cylindrical model (13) is provided with a high-frequency pressure sensor (12); the hypersonic airflow of the high-enthalpy shock tunnel is heated and pressurized twice by shock waves in the low-pressure section (3) to form high total temperature and total pressure gas, and then is accelerated to flow to the test section (5) through the nozzle (4), when flowing through the semi-cylindrical model (13), a standing wave is formed at the leading edge of the semi-cylindrical model (13), the standing wave is a detached wave, and the space between the leading edge of the semi-cylindrical model (13) and the standing wave is a shock wave boundary layer (11); the laser light passes through the shock wave boundary layer (11) from left to right; The signal generator (6), the laser controller (7) and the laser (8) are sequentially connected through cables, the laser light emitted by the laser (8) is reflected by the transmitting end mirror (10), passes through the shock wave boundary layer (11), then enters the photoelectric detector (17) through the optical filter (14), the receiving end mirror (16) and the beam diffusion negative lens (15) in sequence, and the photoelectric detector (17) is sequentially connected with the data acquisition system (18) and the data analysis system (19) through cables; the laser controller (7) is sealed into the test section (5) through cables, and the photoelectric detector (17) is sealed out of the test section (5) through cables.

2. The device for total temperature measurement in high-enthalpy shock tunnels according to claim 1, characterized in that, The signal generator (6) outputs a sawtooth wave with a frequency of 10 kHz to the laser controller (7); The laser (8) is a NO laser, and the center wavelength is 5288.7 nm; The baffle (9) is used for preventing the diaphragm debris in the hypersonic airflow from impacting the laser (8) and the photoelectric detector (17), and the inner diameter of the out-light hole is 20 mm; The frequency response of the high-frequency pressure sensor (12) is not less than 100 kHz; The radius R of the semi-cylindrical model (13) N is 100 mm; the length L of the semi-cylindrical model (13) is the optical path of the laser light, the length L is not less than 500 mm; the surface roughness of the semi-cylindrical model (13) is better than 0.8 μm; The optical filter (14) is used for reducing the interference caused by background light including combustion flame and improving the signal-to-noise ratio of the laser light; A light beam diffusion negative lens (15) reduces the light power density by laser light beam diffusion, protects the photodetector (17) and suppresses background noise; The sampling frequency of the data acquisition system (18) is 20 MHz, and the saving time is 500 milliseconds.

3. The device for total temperature measurement in high-enthalpy shock tunnels according to claim 2, characterized in that, The calculation formula of the thickness δ of the standing wave is as follows: ； wherein, M M∞ is the free stream Mach number; Nozzle chamber temperature T The nozzle chamber temperature T is calculated as a function of the absorbance integrated over each absorption peak as follows: ； wherein is the integrated absorbance of the first absorption peak, is the integrated absorbance of the second absorption peak; is the low energy level energy difference, in cm -1 ; is the low energy level energy before the first absorption peak transition, in cm -1 ; is the low energy level energy before the second absorption peak transition, in cm -1 ; is the reference temperature T r is the absorption line strength at the center frequency of the first absorption peak, in cm T r at 296 K, in cm -2 / atm; is the reference temperature T r is the absorption line strength at the center frequency of the second absorption peak, in cm -2 / atm; h is the Planck constant, in J s; c is the speed of light, in cm / s; k is the Boltzmann constant, in J / K; Absorption line intensity The general formula for the calculation of the absorption line intensity is as follows: ； where E is the low lying state energy in cm -1 ; is the reference temperature T r partition function; is the gas molecule partition function, the gas molecule partition function is the nozzle chamber temperature T is a unique function of is fitted with a polynomial: ； wherein Partition function for gas molecules Coefficients; each fitting coefficient of the NO gas behind the shock wave is obtained by querying the HITRAN spectral database or directly calculated by the HITRAN software JavaHAWKS; The NO molar concentration behind the shock wave X The calculation formula is as follows: ； wherein, P P is the pressure of the gas behind the shock wave, in atm.

4. A method for total temperature measurement in a high-enthalpy shock tunnel, suitable for use with the total temperature measurement device of claim 3, wherein, The method comprises the following steps: S10. Build a total temperature measuring device suitable for high-enthalpy shock tunnel; S20. Debug the laser light path; Switch the laser (8) to a visible red light source to preliminarily adjust the laser light path; then, switch the laser (8) to a laser waveband, connect the oscilloscope to the output signal of the photodetector (17), monitor the sawtooth wave output by the signal generator (6) to the laser controller (7), and accurately adjust the laser light path; S30. Perform high-enthalpy shock tunnel test; The high-pressure section (1) and the low-pressure section (3) of the high-enthalpy shock tunnel are filled with gas with preset pressure and temperature; after reaching the preset pressure and temperature conditions, the diaphragm between the high-pressure section (1) and the low-pressure section (3) is broken, forming a shock wave; the shock wave passes through the trigger sensor (2), the trigger sensor (2) emits a trigger signal to the data acquisition system (18), and the data acquisition system (18) starts collecting and saving 500 milliseconds of data; at the same time, the trigger sensor (2) emits a trigger signal to the laser controller (7), the laser controller (7) controls the laser (8) by adjusting the temperature and current, and the light signal of the laser light emitted by the laser (8) passes through the emission end mirror (10), the shock boundary layer (11), the optical filter (14), the receiving end mirror (16) and the light beam diffusion negative lens (15) in turn, and then enters the photodetector (17) through the optical fiber, the photodetector (17) converts the light signal of the laser light into an electrical signal, and the electrical signal enters the data acquisition system (18) for collection; S40. Data analysis; The data analysis system (19) processes the electrical signal to obtain a TDLAS test result curve, the curve shows that the NO laser with a center wavelength of 5288.7 nm has three absorption peaks, and there are three absorption spectral lines near the wavelength of 5288.7 nm, by calculating the integral absorbance ratio of the absorption peaks combined in pairs, three groups of temperature data are obtained, and finally the total temperature of the flow field is obtained.

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