实验流体力学2017，Vol.31Issue(6)：15-21,7.DOI:10.11729/syltlx20170017
长鳍波动推进流向涡结构PIV试验研究
PIV measurement on streamwise vortex generated by undulating fins
摘要
Abstract
The Gymnarchus Niloticus Fish (GNF) with long undulating fins generally cruises with high efficiency and extra-ordinal maneuverability while keeping its body for straight line. The flow field around andulating fins are measured by phase-locked PIV in the stationary water. Four cross sections including front part, middle part, after-body and wake flow are measured, respectively. Eight equal spaced phases are measured at each cross section, and one hundred instantaneous velocity fields are phase-averaged analyzed to extract the characteristics of vortex structure at each phase. The results indicate in cross sections the streamline vortexes are periodically generated near the fin tip as the fin swings to nearby maximum angle, and shed from the tip of the fin surface, There are two streamwise vortexes generated during each period at the two side maximum angle. On the other hand, as fin swings to the near mid-sagittal plane in the cross section, the fully developed streamwise vortexes begin to decay, and finally disappear. Meanwhile a high speed jet is generated in the direction from the root to the tip of the fin. Comparing the flow structure in the forepart, middle part and posterior cross sections, it is obvious that the streamwise vortex structure and its evolution with phases are similar in these three sections. From the forepart to the posterior along the shaft axis, the flow structure becomes more and more complicated as waves spread downstream, the jet ejected outward from the fin tip becomes stronger, and its sphene of influence seems enlarged. But the flow structure in the wake is different from the above three cross sections, which is less changed with the wave phases. The two large streamwise vortexes are formed under the fin surface, and stably and symmetrically locate on two sides of the mid-sagittal plane with opposite rotation directions.关键词
仿生推进/波动鳍/PIV/涡结构/流向涡Key words
bionic propulsion/undulating fins/PIV/vortex structure/streamwise vortex分类
数理科学引用本文复制引用
张军,白亚强,翟树成,张国平,徐良浩..长鳍波动推进流向涡结构PIV试验研究[J].实验流体力学,2017,31(6):15-21,7.基金项目
国家自然科学基金(51379193) （51379193）
