Boundary-Layer Instability in Transonic Range of Velocities, with Emphasis on Upstream Advancing Wave Packets

摘要

A generalized triple-deck approach is developed for high subsonic and low supersonic velocities, assuming the Reynolds number Re to be large. A longstanding paradox about the boundary-layer stability predicted by the classical version of the triple deck for M_(infinity) > 1 is resolved by discovering a new unstable eigemnode that emerges at some critical value of a transonic similarity parameter. The frequency and both wavenumbers of unsteady spiral Gortler vortices on a concave surface are shown to asymptotically obey in scaled variables the same dispersion relation as incompressible disturbances of a similar type. The famous boundary-layer equations introduced by Prandtl [1] a century ago underlie the extended theory.