An Experimental Model for the Sharp Flat Plate in Rarefied Hvnersonic Flow

Flowfield studies of the shock wave and boundary-layer development on a flat plate are presented for a region that bridges the gap between a classical hypersonic boundary layer downstream and a kinetic flow model at the leading edge. The measurements give a comprehensive picture of the flow pattern in the "merged" or "viscous layer" regime, which exists upstream of the region of validity of hypersonic viscous interaction theory. The results are derived from a combination of several probing and optical techniques and surface pressure measurements. Previous models of slip flow or wedge-like flow were not supported. The shock wave was found to be quite different in thickness and structure from the classical picture of an oblique Rankine-Hugoniot shock, and these effects have not been treated adequately in existing theories. A true scale diagram of the flowfield is given which now makes it possible to evaluate more realistically the theoretical models that have been proposed.