Theoretical Analysis of Near-Free-Molecule Hypersonic Flow at the Sharp Leading Edge of a Flat Plate.

by Andrew F. Charwat

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An analysis by near-free-molecule theory of the initial interactions between a hypersonic free stream and molecules emitted (reflected diffusely) by a cold flat plate immediately downstream of its sharp leading edge. The results give the variations of the pressure, shear, and heat transfer at the wall. These are found to increase downstream from the leading edge and reach a maximum plateau; a subsequent decay of the wall-transfer properties to continuum boundary-layer values can be inferred. The magnitude and location of this plateau compare well with available viscous pressure interaction data. An indication of the initial growth rate of the disturbed merged layer is also obtained from the analysis. It is found that this region is wedgelike and has a slope of about 45 deg from all hypersonic Mach numbers and for wall-to-free-stream-temperature ratios of the order of unity. An analysis by near-free-molecule theory of the initial interactions between a hypersonic free stream and molecules emitted (reflected diffusely) by a cold flat plate immediately downstream of its sharp leading edge. The results give the variations of the pressure, shear, and heat transfer at the wall. These are found to increase downstream from the leading edge and reach a maximum plateau; a subsequent decay of the wall-transfer properties to continuum boundary-layer values can be inferred. The magnitude and location of this plateau compare well with available viscous pressure interaction data. An indication of the initial growth rate of the disturbed merged layer is also obtained from the analysis. It is found that this region is wedgelike and has a slope of about 45 deg from all hypersonic Mach numbers and for wall-to-free-stream-temperature ratios of the order of unity. 73 pp

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