Initial Measurements of Plume Impingement in the NASA Langley 60-foot Vacuum Sphere

An initial characterization of a gaseous, non-combusting ethane plume impinging on a flat plate in the NASA Langley 60-foot vacuum sphere is reported in this work. The motivation for this study is to characterize plume-surface interaction at conditions relevant to large-scale lunar landers. The gas-phase nature of this work focuses on characterization of the supersonic plume impingement on a flat plate. Since this effort is primarily driven to verify that the expected plume flowfield is obtained prior to testing with lunar regolith simulant, this work can be viewed in the context of characterizing a new or modified test facility. As part of these efforts, laser-based measurements are reported for the first time in this large-scale, legacy NASA vacuum facility. Laser Rayleigh scattering imaging, focusing on the region near the impingement plate, shows a clear stagnation shock and quantitative values are reported for the height and curvature of the shock with respect to the flat surface.