| 摘要: |
| 采用均相流模型并结合FBM湍流模型，对绕轴对称回转体通气云状空泡流动特性进行了三维数值模拟，基于实验结果对数值方法进行验证，同时利用基于拉格朗日体系的有限时间李雅普诺夫指数（FTLE）、拉格朗日拟序结构(LCS)和粒子追踪方法分析了其三维非定常脱落特性。研究结果表明：纵截面上空泡覆盖区域的拉格朗日拟序结构整体呈椭球状分布，内部为不规律的复杂拟序结构；不同横截面上拟序结构分布存在很大差异。空泡内部的非对称流动结构和周向流动导致空泡呈现很强的三维运动特性。反向射流在周向上推进的不同步性，是造成空泡呈现不规则断裂和大尺度U型空泡团脱落的主要原因。 |
| 关键词: 通气云状空泡 三维非定常特性 有限时间李雅普诺夫指数 拉格朗日拟序结构 |
| DOI： |
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| 基金项目:国家自然科学基金(51809248，91752105);流体机械及工程四川省重点实验室（西华大学）开放课题（szjj2018-124，szjj2019-024） |
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| Lagrangian-Based Investigation on Unsteady Shedding Behaviors of Three-Dimensional Ventilated Cloud Cavitating Flow |
| DUAN Zhongping,LIU Taotao,ZHANG Mengjie,HUANG Biao,WANG Guoyu |
| (School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China) |
| Abstract: |
| The numerical simulation of ventilated cavitating flow around an axisymmetric body is performed based on a homogeneous model and filter based model(FBM) turbulent model. The numerical results are compared with experimental results. Lagrangian-based methods are applied to get an insight into the three-dimensional unsteady shedding characteristics, including finite-time Lyapunov exponent(FTLE), lagrangian coherent structures(LCS) and particle trajectory. The results show that the whole LCS on the longitudinal section presents elliptical distribution, with irregular and complex LCS inside the cavity. The distribution of LCS on different cross sections show significant difference. Due to the asymmetric flow structure and circumferential motion inside the cavity, three-dimensional characteristics are extremely impressive in the ventilated cavitating flows. It is reasonably deduced that the large-scale U-type shedding cavity is primarily induced by the effect of re-entrant flow motions consisting of moving upstream and circumferential flows as well. |
| Key words: Ventilated cloud cavitating Three-dimensional unsteady characteristics Finite-time Lyapunov exponent Lagrangian coherent structures |