Spectroscopic Flow Evaluation in Inductively Coupled Plasma Wind Tunnel

Abstract

Radiation spectroscopy of high-enthalpy flows in a 110-kW-class inductively coupled plasma wind tunnel is conducted to improve the accuracy of the radiation code and to measure the flow properties in the test section of the wind tunnel in detail. Imaging spectroscopy is done to obtain radial profiles of emission spectra at a single moment, from which the radial distribution of the emission intensity is determined by the inverse Abel conversion. The molecular temperature and the chemical species concentration are determined by the spectrum fitting method through the use of the radiation code, SPRADIAN2. To accomplish better agreement between the numerical predictions and experiments, the theoretical model and the spectroscopic data for the radiation code are replaced with more accurate data to reflect the recent experimental and theoretical results. As a result, the radial distributions of the temperature, the concentration of the impurities as well as the major chemical components, and the flow enthalpy are accurately determined for nitrogen and air flows in the test section of the wind tunnel.