Active control of pressure oscillations in deep cavities excited by a grazing flow

Grazing flow over a deep cavity can result in resonance characterized by a standing wave/vortex feedback loop. Control of cavity resonance has potential impact in stealth aircraft and aircraft wheel well/weapons bay applications, where periodic stress loading can cause material fatigue failure or destruction of instrumentation. A perturbation analysis of the fundamental equations of motion for a fluid system motivates control methods based on interactions of external sources of mass, momentum, and energy with cavity fluctuations.Through proper placement of a screen (drag force) supported by springs in wind tunnel laboratory experiments, the rms pressure level in the cavity was significantly reduced without interacting with the approaching boundary/shear layer. Further reductions were observed when a piezoelectric actuator, a ceramic capable of vibration when alternating current is passed through it, is used to actively vibrate the screen