Flow control using steady blowing and suction strips in a mach 6 boundary layer on a flared cone: “natural” transition

Direct Numerical Simulations (DNS) were carried out in order to explore flow control for transition delay using steady blowing and suction (control) strips at the wall of a flared cone at Mach 6 and zero angle of attack. The flared cone geometry and the flow conditions of the experiments in the Boeing/AFOSR Mach 6 Quiet Tunnel (BAM6QT) at Purdue University were used for the numerical investigations. For the DNS, transition was initiated by introducing random disturbances at the inflow of the computational domain (“natural” transition). The objective of the flow control strategy is to delay or mitigate the negative consequences associated with the nonlinear transition stages, such as the development of hot streaks and large wall pressure amplitudes. Employing steady blowing and suction strips for DNS of a fundamental, that was initiated by a “controlled” disturbance input, has shown a significant delay of the “hot” streak development on the surface of the cone. The DNS results discussed in the present paper indicate that the flow control strategy of using steady blowing and suction strips remains effective even for “natural” transition initiated by random perturbations. Multiple control strips have a compounding effect resulting in a complete prevention of the “hot” streak development so that streaks were no longer observable in the computational domain.