Direct Numerical Simulations (DNS) were carried out in order to explore flow control using steady blowing and suction (control) strips at the wall of a flared cone at Mach 6. 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. The objective of the flow control strategy was to delay or mitigate the negative consequences associated with the nonlinear transition stages, such as the overshoots of skin-friction and heat transfer and the development of hot streaks. A parameter study on the influence of the steady forcing using blowing and suction strips on the fundamental resonance revealed that the most effective location of the control strips to attenuate the growth rate of the secondary disturbance waves is where the primary wave begins to saturate. To effectively suppress the secondary instability mechanism, the required width of the steady blowing and suction strip was approximately four boundary layer thicknesses. Applying one control strip in a fundamental breakdown simulation resulted in significant delay of the '"hot" streak development on the surface of the cone, which was previously observed in experiments and simulations. With an additional blowing and suction strip, the streak onset was delayed so that they were no longer observable in the entire computational domain.
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