Suppression of cavity flow oscillations via three-dimensional steady blowing

This paper presents an investigation of the flow physics and control of cavity flow oscillations using a threedimensional (3-D) array of steady jets located near the cavity leading edge. The array injects 3-D, steady flow normal to the freestreamto suppress the fluctuating surface pressure in a rectangular cavitywith a length-to-depth ratioL/Dof 6 forMach 0.3 to 0.7. Sixteen configurations are assessed for their suppression as a function of the aggregate momentum coefficient Cμ, spatial duty cycle d, and dimensionless wavelength λ/D. Significant reductions of fluctuating surface pressure are observed. Schlierenandparticle image velocimetry are performed to investigate the baselineandcontrolled flows.Companion large-eddy simulationswith spanwise periodic boundary conditions atMach 0.6 generally agreewith the experiments, despite a significant difference in theReynolds numbers.The simulations showthat control reduces the pressure fluctuations inside the entire cavity, albeit at a higher level ofCμ. Spanwisewavelike structures produced by the control input distort the shear layer, inhibit the growth of large-scale vortical structures, and reduce the strength and length scale of turbulent fluctuations near the impingement region.Aslot-configuration design guide is provided,which compares favorably with the limited available data in the literature.