Delay of the Hot Streak Development for a Flared Cone at Mach 6

Direct numerical simulations 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 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, which have been previously observed in experiments and simulations. A parameter study on the influence of the steady blowing and suction strips on the fundamental resonance revealed the most effective location and strength of the control strips to attenuate the growth rate of the secondary disturbance waves. Applying one control strip in a fundamental breakdown simulation resulted in significant delay of the “hot” streak development on the surface of the cone. With an additional blowing and suction strip, the streak onset was delayed so that they were no longer observable in the entire computational domain. The research demonstrates that a detailed understanding of the nonlinear stages of transition can inform the development of effective flow control methods. The presented flow control method is specific to a second-mode-dominated transition scenario (fundamental breakdown).