Effect of Blockage on Periodic Pressure Fluctuations and Shock in Cavitating Flow

Abstract

The intensity of the cavitation shock, the geometry of the cavity and the associated pressure fluctuations in the wake are measured for six different circular cylindrical models. The influence of blockage on these parameters is discussed in detail. In general, with an increase in the blockage ratio, the shock intensity becomes stronger with an increase in the cavitation number. This is noticeable even for small models. With the onset of the shedding-cavity-vortex flow, the shock intensity jumps to a higher value, and the Strouhal number increases. A higher blockage at a given flow velocity or a higher velocity at a fixed blockage tends to accentuate this phenomenon. Shedding of the cavity ceases for λ≥7 (σ≤0.6), however the rear of the cavity shows oscillatory instability resulting in the higher Strouhal number.