Active control of pressure fluctuations in an incompressible turbulent cavity flow

Abstract

Large-eddy simulations of incompressible turbulent boundary layer flows over an open cavity are conducted to investigate the effects of wall-normal steady blowing on the suppression of pressure fluctuations on the cavity walls. The length (L) to depth (D) ratio (L/D) of the cavity is 2 and the Reynolds number based on the cavity depth (ReD) is 12,000. Wall-normal steady blowing is imposed through a limited transverse slot in an upstream region of the cavity leading edge while varying the momentum coefficient (Cμ). As the value of Cμ increases, the pressure fluctuations on the cavity walls decrease mostly due to weakened impingement of turbulent vortical structures residing in the shear layer on the aft wall by lifting effects, reaching a maximum reduction of −7.61% compared to a baseline when Cμ=0.015. However, as the value of Cμ increases further, the pressure fluctuations increase gradually, exceeding that of a baseline when Cμ>0.05. Because intensified turbulent vortical structures in the shear layer with an increase of Cμ lead to strong interactions of small-scale vortices with the cavity walls with an accompanying large motion of the primary recirculation zone within the cavity, additional pressure fluctuations generated on the cavity walls deteriorate the control performance due to the blowing.