Total temperature measuring device and method suitable for high-enthalpy shock tunnel

Abstract

The invention belongs to the technical field of wind tunnel tests, and discloses a total temperature measuring device and method suitable for a high-enthalpy shock tunnel. A signal generator, a laser controller and a laser of the measuring device are sequentially connected through a cable, laser light emitted by the laser is reflected by a transmitting end reflector, penetrates through a shock wave boundary layer, and then enters a photoelectric detector through an optical filter, a receiving end reflector and a light beam diffusion negative lens in sequence; and the photoelectric detector is sequentially connected with a data acquisition system and a data analysis system through cables. The measuring method comprises the steps of building the measuring device; debugging a laser light path; performing a high-enthalpy shock tunnel test; and performing data analysis. According to the measuring device and method, the measuring device is arranged in a test section, airflow is stopped by using a semi-cylindrical model, the total temperature of a flow field is indirectly measured by measuring the temperature after shock wave at the front edge of a semi-cylinder by using the isentropic stagnation principle, the measuring error caused by high pressure is reduced, the measuring precision is improved, and the measuring device and method have engineering practical value.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind tunnel testing, and in particular relates to a total temperature measurement device and method suitable for a high enthalpy shock wave wind tunnel. Background Art

[0002] Shock tunnels utilize moving shock waves to heat and pressurize the test gas, creating hypersonic airflow conditions through nozzle acceleration. Shock tunnels have strong simulation capabilities and are the primary equipment for high-Mach scramjet research. For scramjet engine testing, the test gas is air, with a total flow field temperature of 3000K or higher and a total pressure of tens of MPa. Test times are measured in milliseconds. Tunable semiconductor laser absorption spectroscopy (TDLAS) is highly adaptable to temperature measurements in the high-temperature, low-pressure environments of shock tunnels. However, most current TDLAS temperature measurement studies have a measurement range below 3000K, and at high pressures, adjacent TDLAS spectral lines overlap significantly, weakening the linear temperature dependence and reducing measurement accuracy.

[0003] Currently, there is an urgent need to develop a device and method for measuring the total temperature in high enthalpy shock tunnels. Summary of the Invention

[0004] One technical problem to be solved by the present invention is to provide a total temperature measurement device suitable for high enthalpy shock wave wind tunnels. Another technical problem to be solved by the present invention is to provide a total temperature measurement method suitable for high enthalpy shock wave wind tunnels to overcome the defects of the prior art.

[0005] The total temperature measuring device for a high-enthalpy shock wind tunnel of the present invention is installed in the high-enthalpy shock wind tunnel; the high-enthalpy shock wind tunnel comprises a high-pressure section, a low-pressure section, a nozzle, and a test section connected sequentially from front to back, and a diaphragm is provided between the high-pressure section and the low-pressure section; The trigger sensor of the measuring device is installed in the low-pressure section close to the diaphragm; The measurement device's signal generator, laser controller, data acquisition system, and data analysis system are placed outside the test section. The laser and transmitter reflector are placed on the left side of the test section. A baffle is installed on the test inflow side of the laser, and a corresponding baffle has a light exit hole for the laser light to pass through. The filter, beam diffusion negative lens, receiving reflector, and photodetector are placed on the right side of the test section. A baffle is also installed on the test inflow side of the photodetector, and a corresponding baffle has a light inlet hole for the laser light to pass through. The light inlet hole is covered with a filter. The semi-cylindrical model is installed in the core flow area of ​​the test section, with the axis of the semi-cylindrical model parallel to the laser light and the axis elevation of the semi-cylindrical model at the same height as the laser light. A high-frequency pressure sensor is installed at the leading edge vertex 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, which is then accelerated through the nozzle to flow toward the test section. When flowing 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, and the space between the leading edge of the semi-cylindrical model and the standing shock wave is the shock boundary layer. The laser light passes through the shock boundary layer from left to right. The signal generator, laser controller and laser are connected in sequence through cables. The laser light emitted by the laser is reflected by the transmitting end reflector, passes through the shock wave boundary layer, and then passes through the filter, the receiving end reflector and the beam diffusion negative lens in sequence to enter the photoelectric detector. The photoelectric detector is connected to the data acquisition system and the data analysis system in sequence through cables; the laser controller enters the test section through the cable seal, and the photoelectric detector passes out of the test section through the cable seal.

[0006] Furthermore, the signal generator outputs a sawtooth wave with a frequency of 10 kHz to the laser controller; The laser is a NO laser with a central wavelength of 5288.7 nm; The baffle is used to prevent the membrane debris in the hypersonic airflow from hitting the laser and photodetector. The inner diameter of the light output hole is 20mm. The frequency response of the high-frequency pressure sensor shall not be less than 100kHz; Radius R of the semi-cylinder model N The length L of the semi-cylindrical model is the optical path of the laser light, which is not less than 500 mm. The surface roughness of the semi-cylindrical model is better than 0.8 μm. The filter is used to reduce the interference caused by background light including the burning flame and improve the signal-to-noise ratio of the laser light; Beam diffusion negative lens, which reduces the optical power density by expanding the laser beam, protects the photodetector and suppresses background noise; The sampling frequency of the data acquisition system is 20 MHz, and the storage time is 500 milliseconds.

[0007] Furthermore, the calculation formula of the thickness δ of the standing shock wave is as follows: ; in, M is the incoming flow Mach number; Nozzle chamber temperature T is a function of the integrated absorbance of each absorption peak, the nozzle chamber temperature T The calculation formula is as follows: ; in, is the integrated absorbance of the first absorption peak, The integrated absorbance is the second absorption peak; is the low-level energy difference, unit is cm -1 ; is the low energy level energy before the first absorption peak transition, unit: cm -1 ; is the low energy level energy before the second absorption peak transition, unit: cm -1 ; is the reference temperature T r The absorption line intensity of the first absorption peak center frequency is T r Take 296K, unit cm -2 / atm; is the reference temperature T r The absorption line intensity of the second absorption peak center frequency, unit cm -2 / atm; h is Planck's constant, unit is J s; c is the speed of light, in cm / s; k is the Boltzmann constant, unit is J / K; Absorption line intensity The general calculation formula is as follows: ; in, E is the lower transition 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 The only function of Use polynomial fitting: ; in, is the gas molecule partition function Coefficients; The fitting coefficients of NO gas after the standing shock wave are obtained by querying the HITRAN spectrum database, or directly calculated by the HITRAN software JavaHAWKS; NO molar concentration behind the standing shock wave X The calculation formula is as follows: ; in, P is the NO gas pressure behind the standing shock wave, in atm.

[0008] The total temperature measurement method for a high enthalpy shock tunnel of the present invention comprises the following steps: S10. Build a total temperature measurement device suitable for high-enthalpy shock tunnels; S20. Debug the laser light path; Switch the laser to a visible red light source to perform preliminary adjustments to the laser optical path. Then, switch the laser to the laser band, connect the oscilloscope to the output signal of the photodetector, monitor the sawtooth wave output by the signal generator to the laser controller, and perform precise adjustments to the laser optical path. S30. Conduct high enthalpy shock wave wind tunnel tests; Gas at a preset pressure and temperature is injected into the high-pressure and low-pressure sections of the high-enthalpy shock tunnel. When the preset pressure and temperature conditions are reached, the diaphragm between the high-pressure and low-pressure sections breaks, forming a shock wave. The shock wave passes through a trigger sensor, which transmits a trigger signal to the data acquisition system, which begins collecting and storing 500 milliseconds of data. Simultaneously, the trigger sensor transmits a trigger signal to the laser controller, which controls the laser by adjusting the temperature and current. The optical signal of the laser light output by the laser passes through the transmitting end reflector, the shock wave boundary layer, the filter, the receiving end reflector, and the beam diffusion negative lens in sequence, and then enters the photodetector through the optical fiber. The photodetector converts the optical signal of the laser light into an electrical signal, which enters the data acquisition system for collection. S40. Perform data analysis; The data analysis system processes the electrical signals and obtains a TDLAS test result graph. The graph shows that the NO laser with a central wavelength of 5288.7nm has three absorption peaks, corresponding to three absorption spectral lines near the wavelength of 5288.7nm. By calculating the integrated absorbance ratio of the absorption peaks in pairs, the three sets of temperature data are inverted, and finally the total flow field temperature is obtained.

[0009] The total temperature measurement device and method for a high-enthalpy shock tunnel of the present invention utilizes the three absorption peaks of a single NO laser at high temperature, and inverts three sets of temperature data through any two-by-two combinations of the three absorption peaks, thereby achieving millisecond-level measurements at temperatures of 3000K and above. The total temperature of the test section is indirectly measured by measuring the temperature within the shock boundary layer of a semi-cylindrical model within the test section. By utilizing the fact that the pressure within the shock boundary layer is usually on the order of tens of kilopascals and is 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 using a high-frequency pressure sensor.

[0010] In short, the total temperature measurement device and method for high enthalpy shock wave wind tunnels of the present invention place the measurement device in the test section, use a semi-cylinder model to stagnate the airflow, apply the isentropic stagnation principle, and indirectly measure the total temperature of the flow field by measuring the temperature behind the shock wave at the leading edge of the semi-cylinder; the total temperature measurement device and method for high enthalpy shock wave wind tunnels of the present invention have high-frequency response characteristics, and improve measurement accuracy through low-pressure measurement. It is suitable for measuring the total temperature of transient flow fields in high enthalpy shock wave wind tunnels and has practical engineering value. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram (top view) of the structure of the total temperature measurement device for a high enthalpy shock tunnel according to the present invention; Figure 2 This is a graph of the TDLAS test results obtained in Example.

[0012] 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. Transmitter reflector; 11. Shock wave boundary layer; 12. High-frequency pressure sensor; 13. Semi-cylindrical model; 14. Filter; 15. Beam diffusion negative lens; 16. Receiver reflector; 17. Photodetector; 18. Data acquisition system; 19. Data analysis system. DETAILED DESCRIPTION

[0013] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0014] Embodiment: The total temperature measurement device for a high-enthalpy shock wind tunnel of this embodiment is installed in a high-enthalpy shock wind tunnel; the high-enthalpy shock wind tunnel includes a high-pressure section 1, a low-pressure section 3, a nozzle 4, and a test section 5 connected sequentially from front to back, and a diaphragm is provided between the high-pressure section 1 and the low-pressure section 3; The trigger sensor 2 of the measuring device is installed in the low-pressure section 3 near the diaphragm; The signal generator 6, laser controller 7, data acquisition system 18, and data analysis system 19 of the measuring device are placed outside the test section 5. The laser 8 and the transmitting end reflector 10 are placed on the left side of the test section 5. A baffle 9 is installed on the test inflow side of the laser 8, and a corresponding light exit hole is opened on the baffle 9 for the laser light to pass through. The filter 14, beam diffusion negative lens 15, receiving end reflector 16, and photodetector 17 are placed on the right side of the test section 5. A baffle 9 is also installed on the test inflow side of the photodetector 17, and a corresponding light inlet hole is opened on the baffle 9 for the laser light to pass through. The light inlet hole is covered with the filter 14. A 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 elevation of the semi-cylindrical model 13 is the same as the laser light. A high-frequency pressure sensor 12 is installed at the leading edge vertex of the semi-cylindrical model 13. The hypersonic airflow in the high-enthalpy shock tunnel is heated and pressurized twice by the shock wave in the low-pressure section 3 to form a high total temperature and total pressure gas, which is then accelerated through the nozzle 4 to flow toward the test section 5. When flowing through the semi-cylindrical model 13, a standing shock wave is formed at the leading edge of the semi-cylindrical model 13. The standing shock wave is a detached shock wave, and the space between the leading edge of the semi-cylindrical model 13 and the standing shock wave is the shock boundary layer 11. The laser light passes through the shock boundary layer 11 from left to right. The signal generator 6, laser controller 7 and laser 8 are connected in sequence through cables. The laser light emitted by the laser 8 is reflected by the transmitting end reflector 10, passes through the shock wave boundary layer 11, and then passes through the filter 14, the receiving end reflector 16 and the beam diffusion negative lens 15 to enter the photodetector 17. The photodetector 17 is connected to the data acquisition system 18 and the data analysis system 19 in sequence through cables; the laser controller 7 enters the test section 5 through the cable seal, and the photodetector 17 passes out of the test section 5 through the cable seal.

[0015] Furthermore, 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 wave wind tunnel; Laser 8 is a NO laser with a central 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, which combines with O to form NO. The use of NO laser can measure effective signals at high temperatures. The baffle 9 is used to prevent the membrane debris in the hypersonic airflow from hitting the laser 8 and the photodetector 17. The inner diameter of the light exit hole is 20 mm. The frequency response of the high-frequency pressure sensor 12 is not less than 100 kHz; Radius R of the semi-cylindrical model 13 N The length L of the semi-cylindrical model 13 is the optical path of the laser light, and 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 filter 14 is used to reduce interference caused by background light including the burning flame and improve the signal-to-noise ratio of the laser light; The beam diffusion negative lens 15 reduces the optical power density by expanding the laser beam, protects the photodetector 17 and suppresses background noise; The sampling frequency of the data acquisition system 18 is 20 MHz, and the storage time is 500 milliseconds.

[0016] Furthermore, the pressure and temperature behind the standing shock wave increased significantly. Near the leading edge apex of the semi-cylindrical model 13, the airflow velocity behind the standing shock wave almost stagnated 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 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 nozzle stagnation chamber pressure. The pressure behind the standing shock wave is low pressure. The calculation formula of the thickness δ of the standing shock wave is as follows: ; in, M is the incoming flow Mach number; At 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. The temperature measurement can be achieved by eliminating the pressure and concentration through the ratio. Nozzle chamber temperature T is a function of the integrated absorbance of each absorption peak, the nozzle chamber temperature T The calculation formula is as follows: ; in, is the integrated absorbance of the first absorption peak, The integrated absorbance is the second absorption peak; is the low-level energy difference, unit is cm -1 ; is the low energy level energy before the first absorption peak transition, unit: cm -1 ; is the low energy level energy before the second absorption peak transition, unit: cm -1 ; is the reference temperature T r The absorption line intensity of the first absorption peak center frequency is T r Take 296K, unit cm -2 / atm; is the reference temperature T r The absorption line intensity of the second absorption peak center frequency, unit cm -2 / atm; h is Planck's constant, unit is J s; c is the speed of light, in cm / s; k is the Boltzmann constant, unit is J / K; Absorption line intensity The general calculation formula is as follows: ; in, E is the lower transition 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 The only function of Use polynomial fitting: ; in, is the gas molecule partition function Coefficients, each fitting coefficient has different values ​​according to different gases and temperature ranges; each fitting coefficient of NO gas after the standing shock wave is obtained by querying the HITRAN spectrum database, or directly calculated by the HITRAN software JavaHAWKS; NO molar concentration behind the standing shock wave X The calculation formula is as follows: ; in, P is the NO gas pressure behind the standing shock wave, in atm.

[0017] The total temperature measurement method applicable to a high enthalpy shock tunnel of this embodiment includes the following steps: S10. Figure 1 As shown, a total temperature measurement device suitable for high enthalpy shock wave wind tunnel is built; S20. Debug the laser light path; Switch the laser 8 to a visible red light source to perform preliminary adjustments to the laser optical path; then, switch the laser 8 to the laser band, 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 perform precise adjustments to the laser optical path; S30. Conduct high enthalpy shock wave wind tunnel tests; Gas of preset pressure and temperature is filled into the high-pressure section 1 and low-pressure section 3 of the high-enthalpy shock tunnel; when the preset pressure and temperature conditions are reached, the diaphragm between the high-pressure section 1 and the low-pressure section 3 breaks, forming a shock wave; the shock wave passes through the trigger sensor 2, which transmits 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 transmits a trigger signal to the laser controller 7, and the laser controller 7 controls the laser 8 by adjusting the temperature and current. The optical signal of the laser light output by the laser 8 passes through the transmitting end reflector 10, the shock wave boundary layer 11, the filter 14, the receiving end reflector 16 and the beam diffusion negative lens 15 in sequence, and then enters the photodetector 17 through the optical fiber. The photodetector 17 converts the optical signal of the laser light into an electrical signal, and the electrical signal enters the data acquisition system 18 for collection; S40. Perform data analysis; The data analysis system 19 processes the electrical signal and obtains Figure 2 The TDLAS test result graph shown in the figure shows that the NO laser with a central wavelength of 5288.7nm has three absorption peaks, corresponding to three absorption spectral lines with wavelengths near 5288.7nm. By calculating the integrated absorbance ratios of the absorption peaks in pairs and inverting the three sets of temperature data, the total flow field temperature is finally obtained to be approximately 3600K.

[0018] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the description and implementation methods. For those familiar with the art, all features disclosed in the present invention, or all steps in the disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A total temperature measurement device suitable for high enthalpy shock wave wind tunnel, characterized in that: The measuring device is installed in a high-enthalpy shock wind tunnel; the high-enthalpy shock wind 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 provided 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), laser controller (7), data acquisition system (18) and data analysis system (19) of the measuring device are placed outside the test section (5); the laser (8) and the transmitting end reflector (10) are placed on the left side of the test section (5), and a baffle (9) is installed on the test inflow side of the laser (8), and a light exit hole for the laser light to pass through is opened on the corresponding baffle (9); the filter (14), the beam diffusion negative lens (15), the receiving end reflector (16) and the photoelectric detector (17) are placed on the right side of the test section (5), and a baffle (9) is also installed on the test inflow side of the photoelectric detector (17), and a light inlet hole for the laser light to pass through is opened on the corresponding baffle (9), and the light inlet hole is covered with the 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 elevation of the semi-cylindrical model (13) is the same as the laser light. A high-frequency pressure sensor (12) is installed at the leading edge vertex 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 a high total temperature and total pressure gas, and then passes through the nozzle (4) to accelerate to the test section (5). When flowing through the semi-cylindrical model (13), a standing shock wave is formed at the leading edge of the semi-cylindrical model (13). The standing shock wave is a detached shock wave, and the space between the leading edge of the semi-cylindrical model (13) and the standing shock wave is a shock boundary layer (11); the laser light passes through the shock boundary layer (11) from left to right; 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 reflector (10), passes through the shock wave boundary layer (11), and then passes through the filter (14), the receiving end reflector (16) and the beam diffusion negative lens (15) in sequence to enter the photoelectric detector (17). The photoelectric detector (17) is connected to the data acquisition system (18) and the data analysis system (19) in sequence through cables. The laser controller (7) enters the test section (5) through the cable seal, and the photoelectric detector (17) passes through the test section (5) through the cable seal.

2. The total temperature measurement device for a high enthalpy shock tunnel 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); Laser (8) is a NO laser with a central wavelength of 5288.7 nm; The baffle (9) is used to prevent the membrane debris in the hypersonic airflow from hitting the laser (8) and the photodetector (17), and the inner diameter of the light exit hole is 20 mm; The frequency response of the high-frequency pressure sensor (12) is not less than 100 kHz; 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, and 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 filter (14) is used to reduce interference caused by background light including the burning flame and improve the signal-to-noise ratio of the laser light; A beam diffusion negative lens (15) is used to reduce the optical power density by expanding the laser beam, protect the photodetector (17) and suppress background noise; The sampling frequency of the data acquisition system (18) is 20 MHz, and the storage time is 500 milliseconds.

3. The total temperature measurement device for a high enthalpy shock tunnel according to claim 2, characterized in that: The calculation formula of the thickness δ of the standing shock wave is as follows: ； in, M is the incoming flow Mach number; Nozzle chamber temperature T is a function of the integrated absorbance of each absorption peak, the nozzle chamber temperature T The calculation formula is as follows: ； in, is the integrated absorbance of the first absorption peak, The integrated absorbance is the second absorption peak; is the low-level energy difference, unit is cm -1 ; is the low energy level energy before the first absorption peak transition, unit: cm -1 ; is the low energy level energy before the second absorption peak transition, unit: cm -1 ; is the reference temperature T r The absorption line intensity of the first absorption peak center frequency is T r Take 296K, unit cm -2 / atm; is the reference temperature T r The absorption line intensity of the second absorption peak center frequency, unit cm -2 / atm; h is Planck's constant, unit is J s; c is the speed of light, in cm / s; k is the Boltzmann constant, unit is J / K; Absorption line intensity The general calculation formula is as follows: ； in, E is the lower transition 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 The only function of Use polynomial fitting: ； in, is the gas molecule partition function Coefficients; The fitting coefficients of NO gas after the standing shock wave are obtained by querying the HITRAN spectrum database, or directly calculated by the HITRAN software JavaHAWKS; NO molar concentration behind the standing shock wave X The calculation formula is as follows: ； in, P is the NO gas pressure behind the standing shock wave, in atm.

4. A method for measuring the total temperature of a high enthalpy shock tunnel, which is used in the device for measuring the total temperature of a high enthalpy shock tunnel according to claim 3, characterized in that: The following steps are involved: S10. Build a total temperature measurement device suitable for high-enthalpy shock tunnels; S20. Debug the laser light path; The laser (8) is switched to a visible red light source to perform preliminary adjustment of the laser optical path; then, the laser (8) is switched to a laser band, an oscilloscope is connected to the output signal of the photodetector (17), and the sawtooth wave output from the signal generator (6) to the laser controller (7) is monitored to perform precise adjustment of the laser optical path; S30. Conduct high enthalpy shock wave wind tunnel tests; The high-pressure section (1) and the low-pressure section (3) of the high-enthalpy shock tunnel are filled with gas of 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) breaks, forming a shock wave; the shock wave passes through the trigger sensor (2), and the trigger sensor (2) transmits 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) transmits a trigger signal to the laser controller (7), and the laser controller (7) controls the laser (8) by adjusting the temperature and current. The optical signal of the laser light output by the laser (8) passes through the transmitting end reflector (10), the shock wave boundary layer (11), the filter (14), the receiving end reflector (16) and the beam diffusion negative lens (15) in sequence, and then enters the photodetector (17) through the optical fiber, and the photodetector (17) converts the optical signal of the laser light into an electrical signal, and the electrical signal enters the data acquisition system (18) for collection; S40. Perform data analysis; The data analysis system (19) performs electrical signal processing to obtain a TDLAS test result curve. The curve shows that the NO laser with a central wavelength of 5288.7nm has three absorption peaks, and there are three absorption spectral lines corresponding to the wavelength near 5288.7nm. By calculating the integral absorbance ratio of the absorption peaks in pairs, the three sets of temperature data are inverted, and finally the total temperature of the flow field is obtained.

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