Sheet-to-cloud cavitation in a Venturi pipe is investigated experimentally and numerically in this work. The multiscale vapor structures are simulated by Eulerian–Lagrangian multiscale modeling. The volume of fluid method with adaptive mesh refinement is employed to capture the macroscale cavity features, utilizing the large eddy simulation approach. The results of mesh sensitivity study demonstrate that second-order refinement is capable of capturing phase details and cavitation shedding behaviors. A comparison with experimental results reveals the mechanisms of different types of cavitation shedding induced by reentrant jet and shock wave. Taking microscale bubbles into account using the Lagrangian approach and achieving Eulerian–Lagrangian coupling, the multiscale cavitation features, including the morphological evolution of large cavities and characteristics of microbubbles, are accurately reproduced. The evolution features of microbubbles during pressure wave or condensation shock propagation are well recognized by different changing rates. The results indicate that shedding mechanisms in Venturi pipe cavitation can be categorized into three types: reentrant jet, condensation shock, and pressure wave. In the three conditions investigated in this work, shedding cycles are found to be mainly induced by the reentrant jet (σ = 1.03), reentrant jet, condensation shock, and pressure wave (σ = 0.64), and condensation shock (σ = 0.39), respectively, with a decrease in the cavitation number.

中文翻译：

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通过欧拉-拉格朗日多尺度模拟研究空化脱落机制，包括折返射流和冲击波

这项工作通过实验和数值研究了文丘里管中的片到云空化现象。多尺度蒸汽结构通过欧拉-拉格朗日多尺度建模进行模拟。采用自适应网格细化的流体体积法，利用大涡模拟方法来捕获宏观空腔特征。网格敏感性研究的结果表明，二阶细化能够捕获相细节和空化脱落行为。与实验结果的比较揭示了折返射流和冲击波引起不同类型空化脱落的机制。使用拉格朗日方法考虑微尺度气泡并实现欧拉-拉格朗日耦合，准确再现多尺度空化特征，包括大空腔的形态演化和微气泡的特征。通过不同的变化率可以很好地识别微气泡在压力波或凝结激波传播过程中的演化特征。结果表明，文丘里管空化的脱落机制可分为三种类型：折返射流、凝结激波和压力波。在本工作研究的三个条件中，发现脱落循环主要由再入射流（σ = 1.03）、再入射流、凝结激波和压力波（σ = 0.64）以及凝结激波（σ = 0.39）引起。 ，分别随着空化数的减少而变化。