Study on Flow Characteristics of Compressible Laminar Flow Boundary Layers

The turbulence-transition model developed from the RANS methods has become the most used model in studying flow transition of hypersonic flight vehicles since it overcomes the flaw of stability analysis method that large-scale distributed parallel computing is not applicable. The current turbulence-transition model makes a numerical correction on compressibility in the prediction of transition within the hypersonic boundary layer, resulting in poor generality, so it needs to be further improved and perfected. Targeting this, the equations for the dimensionless boundary layer of compressible flow with pressure gradient are established, with the velocity profile and temperature profile similar outcome of the laminar plate obtained using the local similarity method. The influence of Mach number and pressure gradient on key parameters such as momentum loss thickness and shape factor are explored. The simulation results show that pressure gradient is the key factor for judging transition of the boundary layer. A new fitting equation for determining hypersonic transition model is established.