摘要
Experiments and large-eddy simulations(LESs)are conducted to study the effectiveness and the underlying physical mechanisms of a passive control technique for suppressing the self-sustained oscillations of incompressible flow over aperture-cavities.The control technique is implemented by installing a wedge block above the chamfered leading-edge.The experiments are carried out in a low-speed water tunnel with the freestream velocity ranging from 0.4 m/s to 4.4 m/s,while the large-eddy simulations are carried out corresponding to the experiment at a velocity of 4.0 m/s.The wall pressure fluctuations measured along the cavity floor show that a significant suppression of the self-sustained oscillations of the shear layers can be achieved by the control device.Furthermore,the suppression performance is improved as the freestream velocity increases,not limited to the design point of the control device.The analysis of numerical simulation results focuses on three aspects,the vorticity fields,the velocity fields and the pressure fields,and the physical effects of the control device on the incompressible aperture-cavity flow are visualized.Three mechanisms of suppressing the cavity oscillations are identified from the numerical results,which are the destruction of the large vortex structures by the high frequency vortical excitations,the inhabitation of the intracavity recirculation feedback by introducing the lower shunt flow,and the attenuation of the trailing-edge impingement by thickening the shear layer.
