BAIL 2006 Book of Abstracts - Institut für Numerische und ...

S.A. GAPONOV, G.V. PETROV, B.V. SMORODSKY: Boundary layer intercation with
external disturbances
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M where M = M cos χ and
disturbance amplitude takes place for oblique roughness at = 1
χ is the angle between the roughness wave front and the plate leading edge. At the BL outer edge the
disturbance amplitude is almost zero because it is already damped inside the BL. The problem of
nonlinear interactions of the disturbances induced by sound and roughness was investigated. It has
been found that the parameter, which defines the ability to the instability wave excitation (receptivity
coefficient) is strongly dependent of the acoustics incidence angle and the roughness wave front
orientation. Computations show that even at high subsonic external flow velocities the receptivity is
strongly dependent also on the direction of sound propagation. At M > 1 the instability could be
excited by disturbances with the wavelength much smaller than TS wave wavelength. Maximal
receptivity corresponds to the case when the angle between the roughness wave front and the mean
flow is close to the Mach angle.
The paper presents results of the detailed investigation of the interaction of supersonic BL with
external vortical and thermal perturbations. The boundary conditions for the disturbance at the BL
outer edge are under special consideration. It has been found that inside the BL the streamwise
velocity and mass flux perturbations can exceed much the amplitude of the external vorticity waves.
The disturbance excitation rate is reducing with increasing Mach number. The influence of the
external thermal wave onto the flow inside the BL is considerably The results of the computations of
the intensity and the spatial dimensions of the streamwise streaky structures in the BL are in
agreement with measurements [9].
This work has been performed under the financial support of RFBR and the Russian Federation
President Council (projects 05-01-00079-a, NSh-9642003.1).
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9. Westin K.J.A., BakchinovA.A., Kozlov V.V., Alfredsson P.H. Experiments on localized
disturbances in a flat plate boundary layer. Pt 1: The receptivity and evolution of a localized free
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Speaker: GAPONOV, S.A. 86 BAIL 2006
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