CRITERION FOR THE LAMINAR-TURBULENT TRANSITION ONSET IN A COMPRESSIBLE BOUNDARY LAYER

A criterion of the laminar-turbulent transition onset in a compressible boundary-layer flow is formulated on the base of Liepmann’ assumption according to which the critical condition is reached where the Reynolds stress (caused by the laminar oscillations) becomes equal to the shear stress of the base (undisturbed) flow. Comparison with known results of direct numerical simulations of disturbances propagating in the non-gradient boundary layers on flat plates and sharp cones at zero angle of attack showed that the criterion works well in a wide range of local Mach numbers (0 < Me < 7) for different mechanisms of the nonlinear breakdown of unstable waves.