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 Ma > 1 is resolved by discovering a new unstable eigenmode 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 dispeision relation as incompressible disturbances of a similar type The famous boundary-layer equations introduced by Prandtl [1] a century ago underlie the extended theory.