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

Entropy-layer instabilities in the supersonic flow over a blunted flat plate with a nose radius of R-n=2.5 mm at a Mach number M=2.5 and a unit Reynolds number Re/l=9.9X 10(6)/m are investigated. A type of entropy-layer instability most amplified at zero wave angle is found. Its streamwise wave number and the wall-normal phase distribution of the numerically obtained density eigenfunctions agree with flow-field Visualization using the Schlieren technique. The frequencies of this entropy-layer instability made nondimensional on the basis of an appropriate entropy-layer length scale matches documented experimental observations at a blunted cone. (C) 1999 American Institute of Physics. [S1070-6631(99)01901-7].