Characterization of Arc-heated Wind Tunnel’s Flow Using Tunable Diode Laser Absorption Spectroscopy Coupled with Numerical Analysis

Abstract

This research aims at analysing thermo-chemical properties of the hypersonic high-enthalpy flow in the L2K wind tunnel, situated in Köln at the German Aerospace Center (DLR). In the L2K wind tunnel, Martian atmosphere can be created, and the facility can simulate heat load conditions encountered during atmospheric entry of Martian missions. The focus of this project is the analysis of the non-intrusive experimental technique "Tunable Diode Laser Absorption Spectroscopy" (TDLAS), based on Line Of Sight (LOS) absorption spectroscopy, and applied to hypersonic flow. Martian atmosphere was used, and Carbon Monoxide (CO) line R7 was exploited to gather experimental data. A new interpretation for CO-TDLAS experimental technique applied to hypersonic wind tunnel flow analysis was developed, along with the definition of its points of strength and weakness. Numerical simulations with the DLR-TAU flow solver were used as support of this analysis, and match between simulations and experiments was observed. Flow speed and absorption line’s width were measured, and the knowledge of L2K’s flow structure was extended.