Photogrammetric Surface Analysis of Ablation Processes in High Enthalpy Air Plasma Flow

Kurzfassung

Results from in-situ analysis of ablative heat shield materials based on stereoscopic photogrammetry during plasma wind tunnel testing are presented. A carbon �fiber preform material sample has been investigated in a high enthalpy air flow corresponding to a Hayabusa re-entry condition in 78km altitude. The applied photogrammetry uses two digital single lens reflex (DSLR) cameras triggered at 3 fps to acquire images simultaneously from two different perspectives of the sample exposed to the high Speed flow. The photogrammetric analysis resolves the surface with 25000 px/cm2, approximately 400 dpi, allowing the in-situ analysis of the recession phenomena of ablators. Material inhomogeneities are identified during the ablation process and surface recession is derived with an accuracy of 21 micro�meters. The method is a useful tool for the investigation of temporally resolved volumetric ablation phenomena in low density carbon phenolic materials.