Flow-induced acoustic resonators for separation control

Flow-induced acoustic resonators are employed as passive devices for separation control. The geometry can be adapted in order to ensure resonance under various flow conditions. To enhance the transfer of momentum to the near-wall region downstream of the resonator, its neck geometry was optimized. A further improvement is obtained by operating adjacent resonators in anti-phase. The control success is demonstrated in two different flow configurations: a planar asymmetric diffuser and an airfoil at high angle of attack. Due to the flow-induced resonance the pressure recovery in the diffuser was increased by 18% and the lift of the airfoil rose by up to 36%.

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