Ultrahigh-enthalpy non-equilibrium airflow stagnation point enthalpy measuring method

Abstract

The invention relates to an ultrahigh-enthalpy unbalanced airflow stagnation point enthalpy measuring method which is used for a ground test of an electric arc wind tunnel thermal protection system, and particularly relates to a development-based dual-band laser absorption spectrum measuring method which belongs to the field of aircraft ground aerodynamic thermal test research. Measuring the non-equilibrium temperature of the surface airflow of the water-cooling stagnation point model and the component concentration of atomic nitrogen and oxygen to obtain the internal energy enthalpy and chemical enthalpy of the stagnation point model, thereby realizing the measurement of the superhigh-enthalpy non-equilibrium airflow stagnation point enthalpy; the method provided by the invention can complement the existing method, and fills the gap of enthalpy value measurement in the interval of 50-100MJ / kg in the aerodynamic thermal test; in addition, the method is not limited to measurement of airflow parameters in a test debugging link, and can also realize whole-process flow field parameter monitoring of an aerodynamic heat assessment test of an aircraft thermal protection material.

Description

Technical Field

[0001] The invention relates to the measurement of airflow parameters in ground tests of aircraft, which is used for ground tests of arc wind tunnel thermal protection systems, and in particular to a method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow, belonging to the field of research on ground aerodynamic thermal tests of aircraft. Background Art

[0002] The reentry speed of the spacecraft is getting faster and faster, the flight Mach number can reach Ma=30, and the airflow enthalpy value exceeds 45MJ / kg. At the same time, when the spacecraft reenters the earth, the speed reaches the second cosmic speed, and its airflow enthalpy value is 60MJ / kg. At present, the ground wind tunnel equipment simulates the reentry process of related spacecraft, generally using high-frequency induction plasma heating wind tunnels and MPD magnetic acceleration plasma wind tunnels. For the ground simulation of these two types of wind tunnels, the most critical environment is to carry out the debugging of the airflow parameters of the ground test, among which the enthalpy measurement of the ultra-high enthalpy incoming flow conditions is the top priority.

[0003] Regarding the measurement of enthalpy values ​​of ultra-high enthalpy airflows, the measurement method under lower enthalpy conditions is currently used. The stagnation enthalpy is obtained by measuring the stagnation pressure and stagnation heat flux through a stagnation test piece. This method is based on the classic Fay-Riddell formula. This formula makes many assumptions and does not consider the high enthalpy non-equilibrium effect. It is generally only applicable to enthalpy measurements under conditions below 30MJ / kg. Under higher enthalpy conditions, the accuracy of the formula itself is questionable, and the radiation heat flux under ultra-high enthalpy conditions can no longer be ignored. There is a large measurement error in the stagnation heat flux, so this method cannot meet the enthalpy measurement requirements. The enthalpy measurement method developed by me (ZL201910440190.1) is based on flow conservation and NASA thermochemical equilibrium calculation, and is suitable for enthalpy measurement in the range of 1-25MJ / kg. The patent (ZL201811494282.X) considers enthalpy measurement under low enthalpy conditions, ignores the chemical enthalpy generated by gas dissociation, and measures the airflow temperature and velocity of the free stream at the outlet of the arc heater nozzle to obtain the local total airflow enthalpy at the nozzle outlet, which is suitable for enthalpy measurement in the range of 1.5MJ / kg-7.5MJ / kg; the patents (ZL202111015133.2 and ZL202111012554.X) respectively consider the conditions of pure air medium and argon mixed medium with arc starting, and expand the applicable range of airflow enthalpy to 50MJ / kg. The above work did not involve the measurement of airflow enthalpy under higher enthalpy conditions (≥50MJ / kg) and strong non-equilibrium effects.

[0004] The enthalpy value of airflow is essentially composed of internal enthalpy, kinetic enthalpy and chemical enthalpy: internal enthalpy is related to airflow temperature, kinetic enthalpy is related to airflow velocity, and chemical enthalpy is related to gas components and their mass fractions. When the flat-head stagnation model is used for calibration, the stagnation enthalpy is felt on the surface of the flat-head model, and the airflow on the surface of the flat-head model is stagnant, the velocity is zero, and its kinetic enthalpy is zero. At the same time, for high-enthalpy airflow, when the airflow enthalpy value is high enough and the corresponding temperature is very high, the air will be fully dissociated and ionized, and there will be no molecular oxygen and nitrogen. According to calculations, in the temperature range of 6000-10000K, the gas components are mainly atomic oxygen and nitrogen, and the content of electronic components is low, and the contribution to the chemical formation enthalpy can be ignored. The chemical enthalpy can be obtained by measuring the concentrations of N and O, and the non-equilibrium effect of ultra-high enthalpy airflow makes it impossible to simply use temperature and pressure to calculate and characterize the concentration of gas components. For ultra-high enthalpy gas flow, a very big problem it faces is the high enthalpy non-equilibrium effect, that is, the thermodynamic temperature of the gas cannot be represented by a single temperature, and the thermodynamic temperatures corresponding to different atoms in the gas components are also inconsistent. The high-temperature model generally needs to be expressed in a dual-temperature or triple-temperature manner. For the quantification of the internal energy enthalpy of ultra-high enthalpy gas flow, the gas flow temperature needs to obtain at least two energy levels of temperature, and then further perform temperature coupling to achieve the quantification of the internal energy enthalpy. Summary of the invention

[0005] The technical problem solved by the present invention is as follows: a method for measuring the stagnation enthalpy of ultra-high enthalpy non-equilibrium airflow is proposed. Based on the developed dual-band laser absorption spectroscopy measurement method, the non-equilibrium temperature of the airflow on the surface of a water-cooled stagnation point model and the component concentrations of atomic nitrogen and oxygen are measured to obtain the internal energy enthalpy and chemical enthalpy of the stagnation point model, thereby realizing the measurement of the stagnation enthalpy of the ultra-high enthalpy non-equilibrium airflow.

[0006] The technical solution of the present invention is as follows:

[0007] A method for measuring the stagnation point enthalpy of an ultra-high enthalpy non-equilibrium airflow comprises the following steps:

[0008] (1) Establish a stable flow field environment for ultra-high enthalpy non-equilibrium airflow, place the water-cooling model forwardly downstream of the ultra-high enthalpy non-equilibrium airflow, and measure the stagnation pressure P of the airflow. s ;

[0009] (2) The transmitting end of the dual-band absorption spectrum measurement system generates an incident laser signal, and the laser signal passes along the surface of the water-cooled model and is received by the receiving end on the other side of the dual-band absorption spectrum measurement system to obtain a transmitted laser signal. The integrated area A of each dual band is obtained according to the incident laser signal and the transmitted laser signal. N , A O and the Gauss half-width Δν N Δν O, where the subscripts N and O represent atomic nitrogen and atomic oxygen, respectively;

[0010] (3) Based on the spectral line Gauss half-width Δν N Δν O , and obtain the respective temperatures T of atomic nitrogen and atomic oxygen under non-equilibrium conditions N , T O ;

[0011] (4) Based on the respective temperatures T of atomic nitrogen and atomic oxygen under the non-equilibrium conditions N , T O , get the coupling temperature T s ,in,

[0012] (5) Based on the coupling temperature T s and stagnation pressure P s , get the constant pressure specific heat C p ;

[0013] (6) Based on the constant pressure specific heat C p and coupling temperature T s , and obtain the internal energy enthalpy h s ;

[0014] (7) Based on the integrated area A N , A O , the temperatures of atomic nitrogen and atomic oxygen, respectively, are T N , T O , and the diameter D of the water-cooled model, the mole fractions of atomic nitrogen and atomic oxygen X are obtained N and X O ;

[0015] (8) The molar concentration of atomic nitrogen and atomic oxygen is X N and X O Convert to the mass fraction of atomic nitrogen and atomic oxygen ω N and ω O ;

[0016] (9) Based on the mass fraction ω of the atomic nitrogen and atomic oxygen N and ω O , obtain the chemical enthalpy h c ;

[0017] (10) Based on the internal energy enthalpy h s and chemical enthalpy h c , and obtain the ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy H0.

[0018] In the above-mentioned ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy measurement method, the water-cooling model is a cylindrical shell structure with a cold water pipeline inside, and the shell material is copper.

[0019] In the above-mentioned ultra-high enthalpy non-equilibrium airflow stagnation enthalpy measurement method, in the step (2), the incident laser signal and the transmitted laser signal are divided and then the logarithm is taken, and the Voigt function is used for fitting to obtain the integral area A of each of the two bands. N , A O and the Gauss half-width Δν N Δν O .

[0020] In the above-mentioned ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy measurement method, the step (3) is based on the Gauss half-width Δν of the spectral line. N Δν O , and obtain the respective temperatures T of atomic nitrogen and atomic oxygen under non-equilibrium conditions N , T O ,include:

[0021] T N =14(λ N ·Δν N ) 2

[0022] T O =16(λ O ·Δν O ) 2

[0023] Among them, λ N , O They are the central wavelengths of the two bands in the dual-band laser absorption spectrum measurement system.

[0024] In the above-mentioned ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy measurement method, the coupled temperature T in step (5) is s and stagnation pressure P s , get the constant pressure specific heat C p ,include:

[0025] C p =0.9938-7.787×10 -4 P s +1.98×10 -4 T s +7.067×10 -7 P s ·T s -4.587×10 -8 T s 2 -1.25×10 -10 P s ·T s 2 +4.19×10-12 T s 3

[0026] In the above-mentioned ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy measurement method, the step (6) is based on the constant pressure specific heat C p and coupling temperature T s , and obtain the internal energy enthalpy h s ,include:

[0027] h s =C P ×T s .

[0028] In the above-mentioned ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy measurement method, the step (7) is based on the integral area A N , A O , the temperatures of atomic nitrogen and atomic oxygen, respectively, are T N , T O , and the diameter D of the water-cooled model, the mole fractions of atomic nitrogen and atomic oxygen X are obtained N and X O ,include:

[0029]

[0030] Among them, S(T N )、S(T O ) are the spectral line intensities of the dual-bands of the dual-band laser absorption spectroscopy measurement system.

[0031] In the above-mentioned method for measuring the stagnation enthalpy of ultra-high enthalpy non-equilibrium gas flow, in step (8), the molar concentrations X of atomic nitrogen and atomic oxygen are N and X O Convert to the mass fraction of atomic nitrogen and atomic oxygen ω N and ω O ,include:

[0032]

[0033] Among them, M air is the molar mass of air.

[0034] In the above-mentioned ultra-high enthalpy non-equilibrium gas flow stagnation point enthalpy measurement method, in step (9), according to the mass fraction ω of atomic nitrogen and atomic oxygen N and ω O , obtain the chemical enthalpy h c ,include:

[0035] h c =aω N +bω O

[0036] Among them, a and b are the dissociation energies of atomic nitrogen and atomic oxygen respectively, and the values ​​are a=33.7 and b=15.6.

[0037] In the above-mentioned ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy measurement method, in step (10), based on the internal energy enthalpy h s and chemical enthalpy h c , obtain the ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy H0, including:

[0038] H0=h s +h c .

[0039] In the above-mentioned ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy measurement method, the dual-band λ N , O The value satisfies: N =868.03nm,λ O =777.19nm.

[0040] In the above-mentioned ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy measurement method, the ultra-high enthalpy non-equilibrium airflow is generated by a high-frequency induction plasma heating wind tunnel, or by an MPD magnetic acceleration plasma wind tunnel.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects:

[0042] (1) The embodiment of the present invention proposes a method for measuring the stagnation enthalpy of ultra-high enthalpy non-equilibrium airflow. Based on the developed dual-band laser absorption spectroscopy measurement method, the non-equilibrium temperature of the airflow on the surface of the water-cooled stagnation point model and the component concentrations of atomic nitrogen and oxygen are measured to obtain the internal energy enthalpy and chemical enthalpy of the stagnation point model, thereby realizing the measurement of the stagnation enthalpy of the ultra-high enthalpy non-equilibrium airflow.

[0043] (2) The embodiment of the present invention proposes a method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow. Based on the developed dual-band laser absorption spectroscopy measurement method, the method can realize the measurement of the enthalpy value of airflow under ultra-high enthalpy and non-equilibrium conditions, filling the gap of the existing methods and being suitable for the quantitative measurement of flow fields under strong thermodynamic non-equilibrium conditions.

[0044] (3) The embodiment of the present invention proposes a method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow. The applicable range of the enthalpy value of the method is 30-100 MJ / kg, which can complement the existing method and fill the gap in the enthalpy value measurement of the aerodynamic thermal test in the range of 50-100 MJ / kg.

[0045] (4) The embodiment of the present invention proposes a method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow, which can realize rapid and long-term measurement of the ultra-high enthalpy airflow state, with a response frequency of 100-1000 Hz and a measurement time of 100-3600 s. Therefore, the method is not only limited to the measurement of airflow parameters in the test and debugging link, but can also realize the whole process flow field parameter monitoring of the aerodynamic thermal assessment test of aircraft thermal protection materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of the layout of a method for measuring stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The present invention is further described in detail with reference to the accompanying drawings and embodiments:

[0048] FIG. 1 is a schematic diagram of a layout of a method for measuring stagnation enthalpy of an ultra-high enthalpy non-equilibrium airflow according to an embodiment of the present invention. The method for measuring stagnation enthalpy of an ultra-high enthalpy non-equilibrium airflow according to the present invention comprises the following steps:

[0049] (I) Establish a stable flow field environment of ultra-high enthalpy non-equilibrium airflow, place the water-cooling model forwardly downstream of the ultra-high enthalpy non-equilibrium airflow, and measure the stagnation pressure P of the airflow. s .

[0050] In an optional embodiment, the water-cooling model is a flat-head cylindrical model, that is, a cylindrical shell structure with a cold water pipeline and a pressure measuring device inside, and the shell material is copper.

[0051] In an optional embodiment, the ultra-high enthalpy non-equilibrium airflow is generated by a high-frequency induction plasma heating wind tunnel, or by an MPD magnetic acceleration plasma wind tunnel.

[0052] (ii) The transmitting end of the dual-band absorption spectrum measurement system generates an incident laser signal, which passes along the surface of the water-cooled model and is received by the receiving end on the other side of the dual-band absorption spectrum measurement system to obtain a transmitted laser signal. The incident laser signal is divided by the transmitted laser signal and the logarithm is taken, and the Voigt function is used for fitting to obtain the integral area A of each of the dual bands. N , A O and the Gauss half-width Δν N Δν O , where the subscripts N and O represent atomic nitrogen and atomic oxygen, respectively.

[0053] In an optional embodiment, the dual-band λ N , O The value satisfies: N =868.03nm,λ O =777.19nm.

[0054] (III) Based on the spectral line Gauss half-width Δν N Δν O , and obtain the respective temperatures T of atomic nitrogen and atomic oxygen under non-equilibrium conditions N , T O , the specific calculation formula is as follows:

[0055] T N =14(λ N ·Δν N ) 2

[0056] T O =16(λ O ·Δν O ) 2

[0057] Among them, λ N , O They are the central wavelengths of the two bands in the dual-band laser absorption spectrum measurement system.

[0058] (IV) Based on the respective temperatures T of atomic nitrogen and atomic oxygen under non-equilibrium conditions N , T O , get the coupling temperature T s ,in,

[0059] (V) Based on coupling temperature T s and stagnation pressure P s , get the constant pressure specific heat C p , the specific calculation formula is as follows:

[0060] C p =0.9938-7.787×10 -4 P s +1.98×10 -4 T s +7.067×10 -7 P s ·T s -4.587×10 -8 T s 2 -1.25×10 -10 P s ·T s 2 +4.19×10 -12 T s 3

[0061] (VI) Based on constant pressure specific heat C p and coupling temperature Ts , and obtain the internal energy enthalpy h s , the specific calculation formula is as follows:

[0062] h s =C P ×T s

[0063] (VII) Based on the integral area A N , A O and the respective temperatures T of atomic nitrogen and atomic oxygen N , T O , and the diameter D of the water-cooled model, the mole fractions of atomic nitrogen and atomic oxygen X are obtained N and X O , the specific calculation formula is as follows:

[0064]

[0065] Among them, S(T N )、S(T O ) are the line intensities of the two-band spectral lines in the dual-band laser absorption spectroscopy measurement system, the spectral parameters based on the atomic spectral database and T N , T O You can get it.

[0066] (VIII) The molar concentration of atomic nitrogen and atomic oxygen is X N and X O , converted to the mass fraction of atomic nitrogen and atomic oxygen ω N and ω O , the specific calculation formula is as follows:

[0067] include:

[0068]

[0069] Among them, M air is the molar mass of air.

[0070] (IX) Based on the mass fraction ω of atomic nitrogen and atomic oxygen N and ω O , obtain the chemical enthalpy h c , the specific calculation formula is as follows:

[0071] h c =aω N +bω O

[0072] Among them, a and b are the dissociation energies of atomic nitrogen and atomic oxygen respectively, and the values ​​are a=33.7 and b=15.6.

[0073] (10) Based on the internal energy enthalpy h sand chemical enthalpy h c , the ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy H0 is obtained, and the specific calculation formula is as follows:

[0074] H0=h s +h c

[0075] The method for measuring the stagnation enthalpy of ultra-high enthalpy non-equilibrium airflow proposed in the present invention is based on the developed dual-band laser absorption spectroscopy measurement method, measures the non-equilibrium temperature of the airflow on the surface of a water-cooled stagnation point model and the component concentrations of atomic nitrogen and oxygen, and obtains the internal energy enthalpy and chemical enthalpy of the stagnation point model, thereby realizing the measurement of the stagnation enthalpy of the ultra-high enthalpy non-equilibrium airflow.

[0076] The above description is only the best specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

[0077] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. A method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow, characterized in that: The steps include: (1) Establish a stable flow field environment for ultra-high enthalpy non-equilibrium airflow, place the water-cooling model forwardly downstream of the ultra-high enthalpy non-equilibrium airflow, and measure the stagnation pressure P of the airflow. s ; (2) The transmitting end of the dual-band absorption spectrum measurement system generates an incident laser signal, and the laser signal passes along the surface of the water-cooled model and is received by the receiving end on the other side of the dual-band absorption spectrum measurement system to obtain a transmitted laser signal. The integrated area A of each dual band is obtained according to the incident laser signal and the transmitted laser signal. N , A O and the Gauss half-width Δν N Δν O , where the subscripts N and O represent atomic nitrogen and atomic oxygen, respectively; (3) Based on the Gauss half-width Δν of the spectral line N Δν O , and obtain the respective temperatures T of atomic nitrogen and atomic oxygen under non-equilibrium conditions N , T O ; (4) Based on the respective temperatures T of atomic nitrogen and atomic oxygen under the non-equilibrium conditions N , T O , get the coupling temperature T s ,in, (5) Based on the coupling temperature T s and stagnation pressure P s , get the constant pressure specific heat C p ; (6) Based on the constant pressure specific heat C p and coupling temperature T s , and obtain the internal energy enthalpy h s ; (7) Based on the integrated area A N , A O , the temperatures of atomic nitrogen and atomic oxygen, respectively, are T N , T O , and the diameter D of the water-cooled model, the mole fractions of atomic nitrogen and atomic oxygen X are obtained N and X O ; (8) The molar concentration of atomic nitrogen and atomic oxygen is X N and X O Convert to mass fraction of atomic nitrogen and atomic oxygen ω N and ω O ; (9) Based on the mass fraction ω of the atomic nitrogen and atomic oxygen N and ω O , obtain the chemical enthalpy h c ; (10) Based on the internal energy enthalpy h s and chemical enthalpy h c , and obtain the ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy H0.

2. The method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to claim 1, characterized in that: The water-cooling model is a cylindrical shell structure with a cold water pipeline inside, and the shell material is copper.

3. The method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to claim 1, characterized in that: In the step (2), the incident laser signal and the transmitted laser signal are divided and then the logarithm is taken, and the Voigt function is used for fitting to obtain the integral area A of each of the two bands. N , A O and the Gauss half-width Δν N Δν O .

4. The method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to claim 1, characterized in that: In step (3), based on the spectral line Gauss half-width Δν N Δν O , and obtain the respective temperatures T of atomic nitrogen and atomic oxygen under non-equilibrium conditions N , T O ,include: T N =14(λ N ·Dn N ) 2 T O =16(λ O ·Dn O ) 2 Among them, λ N , O They are the central wavelengths of the two bands in the dual-band laser absorption spectrum measurement system.

5. The method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to claim 1, characterized in that: In step (5), the coupled temperature T s and stagnation pressure P s , get the constant pressure specific heat C p , include: C p =0.9938-7.787×10 -4 P s +1.98×10 -4 T s +7.067×10 -7 P s ·T s -4.587×10 -8 T s 2 -1.25×10 -10 P s ·T s 2 +4.19×10 -12 T s 3 。 6. The method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to claim 1, characterized in that: In step (6), based on the constant pressure specific heat C p and coupling temperature T s , and obtain the internal energy enthalpy h s ,include: h s =C P ×T s 。 7. The method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to claim 1, characterized in that: In step (7), based on the integrated area A N , A O , the temperatures of atomic nitrogen and atomic oxygen, respectively, are T N , T O , and the diameter D of the water-cooled model, the mole fractions of atomic nitrogen and atomic oxygen X are obtained N and X O , include: Among them, S(T N )、S(T O ) are the spectral line intensities of the dual-bands of the dual-band laser absorption spectroscopy measurement system.

8. The method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to claim 1, characterized in that: In step (8), the molar concentration of atomic nitrogen and atomic oxygen is X N and X O Convert to mass fraction of atomic nitrogen and atomic oxygen ω N and ω O , include: Among them, M air is the molar mass of air.

9. The method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to claim 1, characterized in that: In step (9), the mass fraction ω of atomic nitrogen and atomic oxygen is N and ω O , obtain the chemical enthalpy h c ,include: h c =aω N +bω O Among them, a and b are the dissociation energies of atomic nitrogen and atomic oxygen respectively, and the values ​​are a=33.7 and b=15.

6.

10. The method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to claim 1, characterized in that: In step (10), based on the internal energy enthalpy h s and chemical enthalpy h c , obtain the ultra-high enthalpy non-equilibrium airflow stagnation point enthalpy H0, include: H0=h s + h c 。 11. The method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to claim 1, characterized in that: The dual-band λ of the dual-band absorption spectrum measurement system N , O The value satisfies: N =868.03nm,λ O =777.19nm.

12. The method for measuring the stagnation point enthalpy of ultra-high enthalpy non-equilibrium airflow according to claim 1, characterized in that: The ultra-high enthalpy non-equilibrium airflow is generated by a high-frequency induction plasma heating wind tunnel or an MPD magnetic acceleration plasma wind tunnel.

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