Ähnlichkeitsgesetze für Hyperschallströmung

Summary

A flow is termed hypersonic when the free stream Mach numberM _∞ becomes very large. On the body itself, however, the local Mach numbers can still be arbitrarily small. It appears that, the larger the product of free stream Mach number and thickness ratio compared with unity, the better the hypersonic flow condition is fulfilled, i.e. bluff bodies reach hypersonic conditions, with increasingM _∞, quicker than slender bodies. The hypersonic flow pattern is determined essentially by the boundary conditions along the head wave. From considerations of this hypersonic shock it appears that the whole flow pattern of head wave, streamlines and Mach lines, as well as the pressure coefficient, for bodies of arbitrary form and thickness are independent ofM _∞. Further, the pressure coefficient on the surface of slender bodies increases with the square of the thickness; the flow in longitudinal sections of flat bodies can be regarded as two-dimensional and the lift increases mainly with the square of the incidence.