Comparison of supercavity geometry and gas leakage behavior between the double-cavity flow pattern and the wake-closure flow pattern

The objective of this paper is to investigate the effect of two typical supercavity flow patterns (double-cavity and wake-closure) on ventilated supercavity geometry and supercavitating flow structure and further reveal the different mechanisms of gas leakage for these two supercavity flow patterns. An inhomogeneous multiphase model with shear stress transport turbulence was employed to validate the investigation by experimental results. The supercavity geometry was investigated quantitatively between the two supercavity flow patterns by the contrast, and corresponding gas leakage mechanisms were determined. The results show that compared with those of the wake-closure flow pattern, the maximum diameter and full-length of the supercavity with the double-cavity flow pattern decreased by 9.83% and 35.8%, respectively, under the same gas entrainment coefficient. The reason for the apparent difference in the supercavity dimension between the two supercavity flow patterns is that the amount of gas leaking from the closure region is different. For the wake-closure flow pattern, about 6.0% of the ventilated gas leaks from the closure region. However, for the double-cavity flow pattern, more gas leaks from the closure region, which is about four times that of the wake-closure flow pattern. As a result, the mass flow rate of the reverse gas decreases, leading to a decrease in the size of the region where gas flows reversely.