Fp. Liang et al., A STABILITY STUDY OF THE DEVELOPING MIXING LAYER FORMED BY 2 SUPERSONIC LAMINAR STREAMS, Physics of fluids, 8(12), 1996, pp. 3253-3263
An inviscid, parallel, spatial linear stability analysis is performed
on both bounded and semibounded developing mixing layers formed betwee
n a laminar Mach 8 stream and another at Mach 3. Three unstable modes
have been found in the initial mixing zone of the unbounded flow. In t
he downstream region of this flow the slowest of these modes becomes s
table, and the remaining two correspond to the fast and slow modes of
the self-similar mixing layer. For the semibounded flow, a wall in the
slow stream introduces a series of acoustic modes which replace the f
ast mode of the unbounded how. For both the unbounded and the semiboun
ded flows the largest growth rates belong to the slowest mode which re
sides in the developing region and is insensitive to the presence of t
he wall. The existence of this mode has been detected in a wind-tunnel
experiment, at frequency ranges suggested by, and with maximum growth
rates in agreement with, the theory. (C) 1996 American Institute of P
hysics.