Experimental Study of Boundary Layer Effect on the Aeroacoustic Characteristics of the Incompressible Open Cavity

Abstract An experiment platform of cavity flow study was built in the low-turbulence wind tunnel. With the method of installing blocks inside cavities, the boundary layer profiles which drag out the shear layer were changed. Averaged static pressure distribution along the centerline on cavity bottoms, and acoustic spectral characteristics of inspected points on cavity wall were obtained from experiments, to discuss the effect of boundary layer profile change under the condition of low-speed incompressible flow on the cavity (long depth ratio were 2 and 4 respectively) aerodynamic and acoustic characteristics. The results showed that, under the velocity of 30m/s, with the boundary layer thickness increasing, the averaged pressure increased with adverse pressure grads decreased, for cavity of L/D=2, the SPL going down in some degree and when L/D increasing to 4, the SPL increased highly in the range of medium to high frequency.