Cavitation Blog!分享 http://blog.sciencenet.cn/u/jibin08thu 空化机理及其在水力机械中的应用!

博文

绕扭转水翼空化流动的三维大涡模拟及涡动力学分析

已有 5641 次阅读 2013-9-16 18:25 |系统分类:论文交流| and, Large, simulation, Eddy, Three-dimensional

[1] Ji, B., Luo, X. W., Peng, X. X., and Wu, Y. L., 2013, "Three-dimensional large eddy simulation and vorticity analysis of unsteady cavitating flow around a twisted hydrofoil," Journal of Hydrodynamics, 25(4), pp. 510-519. (http://www.sciencedirect.com/science/article/pii/S100160581160390X#)

Full paper.pdf


==============================================================

Abstract:Large Eddy Simulation (LES) was coupled with a mass transfer cavitation model to predict unsteady 3-D turbulent cavitating flows around a twisted hydrofoil. The wall-adapting local eddy-viscosity (WALE) model was used to give the Sub-Grid Scale (SGS) stress term. The predicted 3-D cavitation evolutions, including the cavity growth, break-off and collapse downstream, and the shedding cycle as well as its frequency agree fairly well with experimental results. The mechanism for the interactions between the cavitation and the vortices was discussed based on the analysis of the vorticity transport equation related to the vortex stretching, volumetric expansion/contraction and baroclinic torque terms along the hydrofoil mid-plane. The vortical flow analysis demonstrates that cavitation promotes the vortex production and the flow unsteadiness. In non-cavitation conditions, the streamline smoothly passes along the upper wall of the hydrofoil with no boundary layer separation and the boundary layer is thin and attached to the foil except at the trailing edge. With decreasing cavitation number, the present case has σ = 1.07, and the attached sheet cavitation becomes highly unsteady, with periodic growth and break-off to form the cavitation cloud. The expansion due to cavitation induces boundary layer separation and significantly increases the vorticity magnitude at the cavity interface. A detailed analysis using the vorticity transport equation shows that the cavitation accelerates the vortex stretching and dilatation and increases the baroclinic torque as the major source of vorticity generation. Examination of the flow field shows that the vortex dilatation and baroclinic torque terms increase in the cavitating case to the same magnitude as the vortex stretching term, while for the non-cavitating case these two terms are zero.

Key words: cavitation; Large Eddy Simulation (LES); hydrofoil; vorticity analysis; unsteady shedding;




http://blog.sciencenet.cn/blog-497196-725434.html

上一篇:吴玉林老师团队新书《水力机械振动》(英文版)2013出版
下一篇:在清华度过的2年博士后生活——谨以此文纪念逝去的青春

3 王鑫 强涛 卢东强

该博文允许注册用户评论 请点击登录 评论 (4 个评论)

数据加载中...

Archiver|手机版|科学网 ( 京ICP备07017567号-12 )

GMT+8, 2020-7-4 14:55

Powered by ScienceNet.cn

Copyright © 2007- 中国科学报社

返回顶部