Abstract The shear layer on a supercavity wall is the gas entrainment channel to wake flow for ventilated supercavitating flows with various tail closure modes. To thoroughly understand the gas loss mechanism and the relationship between the gas loss mechanism and dynamic stability of the flows, the flow structures and associated characteristics in the shear layer must be studied. The multi-fluid model used in our previous work is further applied to consider the turbulence of each phase in the flows and then validated again via effectiveness analyses by simulating the ventilated supercavitating flows, including an obvious bubbly wake around a body and the shear-layer characteristic scale of the ventilated supercavity around a single disk cavitator at a low speed. Based on this model, the critical transition criterion is inspected from two vortex tubes to the re-entrant flow closure modes corresponding to different supercavity gas loss mechanisms. The gas volume fraction used to define the supercavity wall and the potential flow solution of the flow velocity on the wall are also examined via simulations. The shear flows are analyzed to reveal the distribution laws of gas velocity in the shear layer under different gravity effects. The shear-layer thickness is calculated and the influence of gravity and water viscous force acting on the outer wall of the supercavity is assessed by analyzing the gaseous velocity distributions in the supercavity cross sections. The results also show that the thickness is sensitive to the inner body shape.

中文翻译：

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通风超腔壁上的剪切层

摘要 超空泡壁上的剪切层是尾流的气体夹带通道，具有多种尾部闭合模式的通风超空泡流。为了彻底理解气体损失机制以及气体损失机制与流动的动态稳定性之间的关系，必须研究剪切层中的流动结构和相关特性。我们之前工作中使用的多流体模型被进一步应用于考虑流动中每一相的湍流，然后通过模拟通风超空泡流的有效性分析再次验证，包括围绕物体和剪切层的明显气泡尾流低速下单个圆盘空化器周围的通风超空腔的特征尺度。基于这个模型，从两个涡流管到对应于不同超腔室气体损失机制的重入流关闭模式，检查了临界过渡标准。用于定义超腔壁的气体体积分数和壁上流速的潜在流动解也通过模拟进行了检查。通过对剪切流的分析，揭示了不同重力作用下剪切层中气体速度的分布规律。计算剪切层厚度，并通过分析超腔截面中的气体速度分布来评估重力和水粘滞力对作用在超腔外壁的影响。结果还表明，厚度对内部体型很敏感。