Laminar Supersonic Boundary Layer of the Binary Gas Mixture

Theoretical investigation of the properties of a compressible binary-mixture boundary-layer in the framework of local self-similar boundary-layer equations. We have considered the problem, when the foreign gas of various molecular weights – lighter and heavier than air – has been injected into the flat-plate boundary-layer through the permeable model surface. Computations of the binarymixture velocity, density and temperature profiles as well as foreign gas concentration in such boundary layers at different Mach numbers have been performed. It has been found that increase of a foreign gas injection leads to a monotonous decrease of the skin friction and heat transfer coefficients. It has been established that at free stream Mach number M≈2 action of a heavy gas injection from the model surface into the boundary layer is similar to the action of the model cooling. This injection increases the density of the mixture near the wall. As a result, the profiles of the supersonic boundary layer are modified in such a way that the boundary-layer linear stability should be increased with injection of a foreign gas with high molecular weight. This in turn should lead to a shift in position of the laminar-turbulent transition downstream.

Keywords:
supersonic boundary layer, hydrodynamic stability, laminar-turbulent transition, binary gas mixtures. 
УДК 532.526

Laminar Supersonic Boundary Layer of the Binary Gas Mixture