Temperature Measurements in an Arc-Heated Plasma Wind Tunnel by Laser-Induced Fluorescence

摘要

Laser-induced fluorescence using the A-X(0,0) band for excitation of nitric oxide is a promising approach for examining high-enthalpy flows. Spectroscopic investigations within this excitation wavelength band intend to identify appropriate transitions that maximize the fluorescence signal and minimize possible interference with other species. Special emphasis was placed on the comparison of the temperature measurements and the computational fluid dynamics calculations based on an equilibrium model. The flow simulations are conducted with a Navier-Stokes multiblock, which is a multiblock structured finite volume solver. The rotational temperatures of nitric oxide within a high-enthalpy flow, with a stagnation enthalpy of 3.6MJ/kg, were measured by two-line and multiline thermometry methods using laser-induced fluorescence. For the purpose of validation, the measurement and calculation method was applied to simulated excitation spectra, a test cell, and a well-characterized flat flame burner. Comparisons between spectroscopy measurements and freestream temperature calculations showed a good agreement. Additionally, the spectroscopy measurement results were consistent with the theoretical approach of thermochemical equilibrium.