Control of Laminar-to-Turbulent Transition in Hypersonic Boundary Layer with Shallow Micro-Pores

Turbulent transition delay in hypersonic boundary layer with shallow micro-pores is numerically investigated. The Mack second mode, a dominant instability in hypersonic boundary layer, can be suppressed with micro-pores, thereby delaying the transition. In contrast to previous studies, the current study explores shallow pores considering manufacturability of millions of microscale pores. Linear stability theory (LST) is utilized to find an optimal geometry of shallow pores that provides significant stabilization of the Mack second mode, complying the manufacturing constraint. To demonstrate the transition delay, direct-numerical simulation (DNS) coupled with the LST is conducted. The Mack second mode and a pair of oblique modes, identified by LST, are introduced at the inlet of DNS domain with laminar solution. An impedance model simulates the absorption characteristics of porous surface without resolving millions of micro-pores in DNS. Detailed analyses with comparison to experiments will be included in the presentation.