Local flows in a laminar boundary layer flowing over surface heating elements are investigated. Mathematical models of disturbed flows are constructed on the basis of an asymptotic analysis and the similarity parameters are determined. The time-dependent local heating regimes ensuring control of separation and flow stability in the boundary layer are studied. The results of a numerical and analytic analysis are obtained.

We analyse the disturbed flow in the subsonic laminar boundary layer, disturbances being generated by local heating elements, which are placed on the surface. It is exhibited that these flows are described in terms of free interaction theory for specific sizes of thermal sources. We construct the numerical solution for the case of a flat subsonic stream in the viscous asymptotic layer, in which the flow is described by nonlinear equations for vorticity, temperature and an interaction condition which provides the influence of perturbations to the pressure in the main order. The obtained solutions are compared with those for corresponding linear problems with small perturbations. It is demonstrated that strong temperature perturbations in some situations allow us to obtain the flow close to the separated flow.

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A three-dimensional (3D) structure of a separated §ow in a compression corner at a free-stream Mach number í = 6 is studied. The model is a §at plate with an almost sharp leading edge on which a 30 • ramp is mounted. The spanwise size of the model is equal to the length of the plate from the leading edge to the ramp. The angle of attack is varied from 0 • to 15 • . The shock wave structure of the §ow near the model is shown. The existence of a thin high total pressure layer (dynamic layer) is found. The dynamic layer is located above the boundary layer on the ramp, downstream from the reattachment line. The existence streamwise vortices near the reattachment line is shown. The measured spectra of the wall pressure §uctuations in the reattachment region are presented.

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