Determination of NO-Rotational and Vibrational Temperature Profiles in a High Enthalpy Flow Field with NONEQUILIBRIUM

Abstract

The Laser Induced Fluorescence technique (LIF) was used for the determination of vibrational and rotational temperatures and the concentrations of NO-molecules in free stream regions and near models in the arc-heated high enthalpy facilities (LBK) of DLR in Cologne. The main advantages of this non-intrusive spectroscopic technique are the high selectivity and its good sensitivity combined with excellent resolution and the possiblity to measure simultaneously spatially resolved temperatures and concentration profiles in planes or along lines. In the free stream regions the vibrational and rotational temperatures of NO are nearly identical, while in the shock layer the vibrational temperatures of NO are lower compared to its rotational temperatures. The measured values are compared with results from aerothermodynamic calculations and with results from N2-CARS-measurements, which have been performed in LBK using the same flow condition and model configuration. The different vibrational temperatures of NO and N2 in the free stream and in the shock layer are explained by the faster vibrational relaxation of NO compared to N2