Martian flow characterization using tunable diode laser absorption spectroscopy, in high enthalpy facilities

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Martian flow characterization using tunable diode laser absorption spectroscopy, in high enthalpy facilities

Salvi, Ciro / Steffens, Lars / Hohn, Oliver / Gülhan, Ali / Maggi, Filippo

Abstract This research aims at analyzing 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 absorption spectroscopy, and applied to hypersonic flow. A simplified Martian atmosphere (97% ${CO}_{2}$ and 3% $N_{2}$ ) was used. A new interpretation for CO-TDLAS experimental technique applied to hypersonic wind tunnel flow analysis was developed. Numerical simulations with the DLR-TAU non-equilibrium 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.

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Highlights • TDLAS experimental technique in L2K wind tunnel was comprehensively analyzed. • Recirculation process of the flow’s outer layers was confirmed and analyzed. • Match between simulations of spectroscopic data and experiments was observed.