Passive control of high-speed boundary layer transition using non-uniform surface temperature distributions

This is the authors' abstract. We don't add key points for this paper.

View Video Presentation: https://doi.org/10.2514/6.2023-0849.vid We propose a control method utilizing non-uniform surface temperature distribution to delay laminar-turbulent transition. Laminar-turbulent transition in hypersonic flow causes an increase in aerodynamic heating, and transition control is crucial to suppress the heat flux. Our proposed method exploits spanwise temperature variations on the surface to generate streaks in order to delay transition. Direct Numerical Simulation (DNS) is conducted to assess a hypersonic flow field at Mach 6 with specified non-uniform temperature distributions on the wall. DNS shows that streaks are generated in the boundary layer, and instability is suppressed successfully, assessed by the energy of the perturbed wall-normal velocity. Design of the experiments to prove the concept has been explored, referring to the configurations of the Imperial College London supersonic wind tunnel at Mach 2, 2.75 and 5. A flat plate test article has been designed to achieve non-uniform temperature distributions via heat transfer between a growing boundary layer and strips made from different materials with different thermal properties. A thermal model predicts temperatures on the flat plate test article's surface passively become non-uniform. The feasibility of the experiment has been validated by two dimensional Reynolds-averaged Navier-Stokes (RANS) simulation.