Allowance for gas compressibility in the $\gamma$-model of the laminar–turbulent transition

The formulation and applicability range of the $\gamma$-model of laminar–turbulent transition are analyzed. Its implementation in the EWT-TsAGI application package and verification results for the problem of computing a transitional boundary layer on a plate are described. The cases of zero and adverse pressure gradients are considered. A modification of the $\gamma $-model that takes into account the effect of compressibility on the laminar–turbulent transition location is proposed. Two problems are considered to calibrate and test the correction term: the flow over the LV6 laminar-flow airfoil and the flow over the nacelle of a bypass turbojet engine. It is shown that, with the used of the proposed correction, the laminar–turbulent transition location can be correctly predicted in transonic flow regimes.