In non-steady and high-speed flowing high-temperature environments, local thermal non-equilibrium phenomena are widely present. Therefore, if the Boltzmann distribution, which uses a single temperature to describe the energy level distribution of molecules, is adopted, a large error may exist. To solve this problem, a two-temperature / three-temperature model is often used to calculate the spectral radiation characteristics of OH in local thermodynamic non-equilibrium states. In this paper, taking the BSUV-2 aircraft at a flight altitude of 100 km as an example, The OH radiation characteristics in shock waves with a wavelength range of 305nm-315nm were calculated using the two-temperature model. By comparing the relative spectral radiance of experimental spectra and calculated spectra of OH, the optimal calculation range of vibrational temperature was determined to be 2000K-4000K. This method of measuring rotational temperature has significant advantages in low-resolution situations. After determining the rotational temperature, by simulating and calculating the normalized OH spectral radiance corresponding to different vibrational temperatures in the wavelength range of 270nm-340nm, it was found that the maximum intensity peak G1 is not affected by temperature, while the second largest intensity peak G2 has a linear relationship with temperature. Therefore, we can use the ratio of G1 to G2 to invert the range of rotational temperature. This study shows that using a two-temperature thermodynamic non-equilibrium model in local thermodynamic non-equilibrium states can achieve temperature inversion and accurately describe the spectral radiation characteristics of OH molecules, providing an important reference for related research fields.
The non-equilibrium ultraviolet radiation characteristics of plume and shock are closely related to flight parameters such as vibration-rotation temperature, where temperature is the most important thermodynamic quantity for calculating non-equilibrium radiation. CN is the main product of aircraft reentry into the atmosphere and the ablation of carbon-based composite materials, and has very high emission efficiency, making it one of the best molecules for high-temperature gas temperature measurement. In this paper, the two-temperature model and the line-by-line method are used to calculate the CN ultraviolet spectral radiance, and the spectral structure of the violet band is analyzed. The effects of vibration temperature and rotation temperature on the spectral intensity and spectral shape of ultraviolet radiation under thermodynamic non-equilibrium conditions are discussed. According to the relationship between the band tail of CN violet band v=0 peak and the vibration temperature and rotation temperature, a method to invert the rotation temperature using the the slope of CN spectral relative intensity
The non-equilibrium ultraviolet radiation characteristics of plume and shock are closely related to flight parameters such as vibration-rotation temperature, where temperature is the most important thermodynamic quantity for calculating non-equilibrium radiation. CN is the main product of aircraft reentry into the atmosphere and the ablation of carbon-based composite materials, and has very high emission efficiency, making it one of the best molecules for high-temperature gas temperature measurement. In this paper, the two-temperature model and the line-by-line method are used to calculate the CN ultraviolet spectral radiance, and the spectral structure of the violet band is analyzed. The effects of vibration temperature and rotation temperature on the spectral intensity and spectral shape of ultraviolet radiation under thermodynamic non-equilibrium conditions are discussed. According to the relationship between the band tail of CN violet band v=0 peak and the vibration temperature and rotation temperature, a method to invert the rotation temperature using the the slope of CN spectral relative intensity
The earth background radiation is an important factor in the detection of space to earth, since it is necessary to study the influence of different surface on infrared detection. In this research, the daytime atmospheric meteorological data of 2021 summer solstice in typical areas of China are measured by multichannel infrared radiometer SABER(Sounding of the Atmosphere using Broadband Emission Radiometry). Calculated the infrared background radiation with a wavelength of 1-6 μm, at a same time, compared the results of the measured data in the South China Sea with the results of the Standard data. The calculation results show that the difference in the earth background radiation calculated by the standard in different regions is not obvious. The atmospheric data can more accurately reflect the earth background radiation of different surface types. At the time, in different regions the earth background radiation is mainly concentrated in the 1-2.5 μm band, the infrared background radiation in desert and forest region is stronger than that in snow mountain region, and the radiation intensity in ocean region is weakest.
The flow field around the hypersonic vehicle is in a thermodynamic and chemical non-equilibrium state when it reenters the atmosphere. The excited state level number density of the molecular atoms no longer satisfies the Boltzmann distribution in the thermochemical non-equilibrium state. In order to accurately calculate the spectral radiation characteristics of NO (A2Σ+), a collision-radiation (C-R) model coupled with N2 is used to consider the excited state population from the microscopic process of its level transition in this paper. HITRAN 2020 database and line-by-line (LBL) method are used to calculate the high-resolution spectral absorption coefficient. And then combined with the line of sight (LOS) method, the ultraviolet (UV) spectral radiation produced by the NO (A2Σ+ ) is calculated. The translational temperature, vibration temperature and two-temperature model are used to characterize the reaction rate retrospectively so as to obtain the NO excited state number density and UV spectral radiation under thermodynamic and chemical non-equilibrium states. The shock layer experiment of BSUV with a flight altitude of 38km and speed of 3.5km/s is taken as an example, the effect of different characterization temperatures on spectral radiance is analyzed and the optimum characterization temperature of NO (A2Σ+ ) non-equilibrium UV radiation is obtained. The results show that characterizing the NO(A) number density with the translational temperature, rather than the vibrational temperature and two-temperature model, yields a better comparison to the flight experimental data.
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