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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.

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To investigate the influence of flow field's radial dimension on the flow of the portion gas-leakage supercavity, based on the two-fluid multiphase flow model and SST turbulence model, considering the compressibility of ventilated gas, a 3D simulation model of ventilated supercavity was established to simulate the flow of the supercavitation, which was consistent with water tunnel experiment. The effect of flow field's radial dimension on ventilated supercavity's dimension and pressure distribution was studied. The results show that flow field's radial dimension has a significant effect on the ventilated supercavity's dimension and pressure distribution. When flow field's radial dimension ratio is 6.5 times lower than the maximum diameter of supercavity, the supercavity cannot be formed to completely enclose the underwater vehicle. With the increase of flow field's radial dimension, the pressure inside and outside the supercavity decreases, and there is a pronounced increase in supercavity dimension. When flow field's radial dimension ratio is 54.0 times greater than the maximum diameter of supercavity, the dimension and pressure distribution of ventilated supercavity remain unchanged, which coincides with the theoretical results. In addition, the calculation results provide a criterion for simulating the shape of ventilated supercavity in the open environment, which can be used to guide engineering practice.

To study the influence of attack angle on ventilated supercavitating flow, a numerical model is established to simulate the supercavitation flow by using the inhomogeneous multiphase flow model and the SST k-ω turbulence model. And then, the model is verified and validated by comparing with the experimental results. The effect of attack angle on the profile of ventilated supercavity was numerically investigated over high Froude number. Results show that the attack angle causes the linear deviation of the ventilated supercavity axis, the deviation angle is in direct proportion to the attack angle, the deviation direction is opposite to the lift of the cavitator, and the deformation of the supercavity contour increases along the flow direction. The attack angle changes the gas flow structure inside the ventilated supercavity, causing the different deformation of the upper profile and lower profile. Under the condition of positive attack angle, the deformation of the lower profile of the supercavity generated by the disk cavitator is significantly greater than that of the upper profile.