涡环物理特征的研究  

The investigation on physical features of vortex rings

作　　者：向阳[1,2] 刘洪[1,2] 吴镇远[1,2] 

机构地区：[1]上海交通大学航空航天学院,上海200240 [2]上海交通大学吴镇远空气动力学中心,上海200240

出　　处：《空气动力学学报》2014年第2期159-165,共7页Acta Aerodynamica Sinica

基　　金：973项目(2014CB744802)

摘　　要：通过数值模拟涡环的形成,进而采用基于涡环的随体坐标系下的流函数方法确定涡环的边界,分析不同形成时间(活塞冲程/活塞直径)涡环的物理特征参数(涡环的体积、半径、能量等参数)的变化。通过与实验结果和Slug模型的理论分析结果做对比,该方法能合理地确定涡环的边界和其它物理特征参数。进一步研究中发现当形成时间小于4(此时涡环发生夹止)时,涡环的涡核半径随形成时间的增加而增加,夹带能力在下降,而当形成时间大于4后,涡环的涡核半径不再进一步增加,并且夹带能力开始增大。During the past several decades,researches on physical features of vortex rings have not been well understood.Shariff（Annu.Rev.Fluid Mech.1992,24：235-79）summarized the researches on the evolution and transmission process of vortex rings,Dabiri（Annu.Rev.Fluid Mech.2009,41：17-33）further explores the dynamic feathers of vortex ring and the effect on bio-propulsion system,the aim of researches on vortex ring is to reveal the fundamental reasons why animals can product high lift force and large thrust. However,the formation and evolution of vortex ring and the corresponding fluid dynamics both lack thorough analysis.One important reason is that the boundary and physical feather parameters cannot be determined clearly.In this paper,the evolution process of vortex rings is solved by numerical simulation,and then the boundary of vortex ring is defined on the basis of stream function with body coordinate system, meanwhile,the physical feathers of vortex ring with different formation times（the stroke of piston/the diameter of piston）can be investigated.Compared with the Gharib′s（J.Fluid Mech.1998,360：121-140）experimental conclusions and the analytical results based on Slug model,stream function method can determine the boundary of vortex ring and the physical parameters of vortex ring reasonably.Moreover,the vortex core radius increases with formation time,but the ability of entrainment decreases with formation time,when the formation time of vortex ring is smaller than four.However,when the formation time exceeds four,the radius of vortex ring core no longer increases with formation time and the entrainment ability begins to increase.

关 键 词：涡环 形成时间 流函数 物理特征 

分 类 号：V211.3[航空宇航科学与技术—航空宇航推进理论与工程]