Abstract Partial cavitation over incipient, transitory and periodic regimes is investigated using large eddy simulation (LES) in the (experimental) sharp wedge configuration of Ganesh et al. (2016). The numerical approach is based on a compressible homogeneous mixture model with finite rate mass transfer between the phases. Physical mechanisms of cavity transition observed in the experiments; i.e. re-entrant jet and bubbly shock wave, are both captured in the LES over their respective regimes. Vapor volume fraction data obtained from the LES is quantitatively compared to X-ray densitometry. In the transitory and periodic regimes, void fractions resulting from complex interactions of large regions of vapor in the sheet/cloud show very good comparison with the experiments. In addition, very good agreement with the experiments is obtained for the shedding frequency and the bubbly shock wave propagation speed. In the incipient regime, the qualitative characteristics of the flow (e.g. cavitation inside spanwise vortices in the shear layer) are captured in the simulations. Conditions favoring either the formation of the re-entrant jet or the bubbly shock wave are analyzed by contrasting the LES results between the regimes. In the transitory regime, large pressure recovery from within the cavity to outside, and the resulting high adverse pressure gradient at the cavity closure support the formation of re-entrant jet. In the periodic regime, overall low pressures lead to reduced speed of sound and increased medium compressibility, favoring the propagation of shock waves. In a re-entrant jet cycle, vapor production occurs predominantly in the shear layer, and intermittently within the cavity. In a bubbly shock cycle, vapor production is observed spanning the entire thickness of the cavity. Bubbly shock wave propagation is observed to be initiated by the impingement of the collapse-induced pressure waves from the previously shed cloud. Supersonic Mach numbers are observed in the cavity closure regions, while the regions within the grown cavity are subsonic due to the negligible flow velocities.

中文翻译：

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使用大涡模拟对楔形部分空化状态进行数值研究

摘要 使用大涡模拟 (LES) 在 Ganesh 等人的（实验）尖锐楔形配置中研究了初始、过渡和周期状态下的部分空化。(2016)。数值方法基于可压缩的均质混合物模型，在相之间具有有限速率的传质。实验中观察到的空腔转变的物理机制；即折返射流和气泡激波，都在 LES 中捕获到它们各自的状态。从 LES 获得的蒸气体积分数数据与 X 射线密度测定法进行了定量比较。在瞬态和周期性状态下，片/云中大面积蒸汽的复杂相互作用产生的空隙率与实验进行了很好的比较。此外，脱落频率和气泡冲击波传播速度与实验非常吻合。在初始状态下，流动的定性特征（例如剪切层中展向涡旋内的空化）在模拟中被捕获。通过对比不同状态之间的 LES 结果，分析了有利于形成折返射流或气泡冲击波的条件。在过渡状态下，从空腔内部到外部的大压力恢复，以及在空腔闭合处产生的高逆压梯度支持折返射流的形成。在周期性状态下，整体低压导致声速降低和介质可压缩性增加，有利于冲击波的传播。在重入喷射循环中，蒸汽的产生主要发生在剪切层中，间歇性地发生在空腔中。在气泡冲击循环中，可以观察到跨越腔体整个厚度的蒸汽产生。观察到气泡冲击波的传播是由来自先前脱落的云的坍缩引起的压力波的撞击引发的。在空腔闭合区域观察到超音速马赫数，而由于流速可忽略不计，生长空腔内的区域是亚音速的。