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 Rn=2.5 mm at a Mach number M=2.5 and a unit Reynolds number Re/l=9.9×106/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.