Entropy-layer instabilities over a blunted flat plate in supersonic flow

Entropy-layer instabilities in the supersonic flow over a blunted flat plat e with a nose radius of R-n=2.5 mm at a Mach number M=2.5 and a unit Reynol ds number Re/l=9.9X 10(6)/m are investigated. A type of entropy-layer insta bility most amplified at zero wave angle is found. Its streamwise wave numb er and the wall-normal phase distribution of the numerically obtained densi ty eigenfunctions agree with flow-field Visualization using the Schlieren t echnique. The frequencies of this entropy-layer instability made nondimensi onal on the basis of an appropriate entropy-layer length scale matches docu mented experimental observations at a blunted cone. (C) 1999 American Insti tute of Physics. [S1070-6631(99)01901-7].