Investigations on vortex structures for undulating fin propulsion using phase-locked digital particle image velocimetry  

作　　者：Ya-qiang Bai Jun Zhang Shu-cheng Zhai Guo-ping Zhang 

机构地区：[1]China Ship Scientific Research Center,Wuxi,214082,China [2]National Key Laboratory on Ship Vibration and Noise,Wuxi,214082,China

出　　处：《Journal of Hydrodynamics》2021年第3期572-582,共11页水动力学研究与进展B辑（英文版）

基　　金：Projects supported by the National Natural Science Foundation of China(Grant Nos.51379193,51779233).

摘　　要：The Gymnarchus niloticus fish can swim in surging and heaving directions only with a long undulating ribbon fin while keeping its body along almost straight line.These features substantially inspire the design of underwater vessels with high maneuverability and station keeping performance,which is characterized by peculiar vortex structures induced by undulating fin propulsion.To reveal the propulsion mechanism under the evolution of these complex vortex structures,the variation of velocity field with the undulating fin’s wave phase on cross section and mid-sagittal plane at wave amplitude of 85°is investigated by phase-locked digital particle image velocimetry(DPIV).Through experimental flow field images,two typical vortex structures are clearly identified,i.e.,streamwise vortex and crescent vortex,which is further explained by supplemental numerical simulations using large eddy simulation.Vortex characteristic and its evolution on cross sections and mid-sagittal planes is investigated,and its relationship with thrust,heave force is also analyzed.It is found that the two kinds of vortexes induce the main hydrodynamic forces in two directions synchronously,which brings the undulating fin propulsion an extra-ordinal maneuverability.The research will be useful for understanding the potential mechanism of this novel propulsion and is of great application prospect in designing more maneuverable underwater vehicles.

关 键 词：Undulating fin propulsion vortex structure phase-locked digital particle image velocimetry(DPIV) hydrodynamic mechanism 

分 类 号：O35[理学—流体力学]