柔性长鳍波动推进试验及分析

以依靠长背鳍推进的“尼罗河魔鬼”为研究对象,对柔性长鳍波动推进模式的运动学进行了研究。介绍了“尼罗河魔鬼”巡航游动试验的实验原理及方法,通过试验揭示了波动柔性长背鳍的形态学特征、运动特性及运动参数间的相关性,定性描述了“尼罗河魔鬼”正、逆向行进时背鳍产生波形的差异,在此基础上建立了柔性长鳍波动的运动学简化模型,利用细长体理论估算样本巡航游动时的水动力学效率大于83.12%。

Examination and Analysis of Undulatory Dorsal Fin Propulsion of Gymnarchus Niloticus

This paper introduces the experimental principle and method on undulatory dorsal fin propulsion of gymnarchus niloticus,a large aggressive fish whose swimming mode is referred to as amiiform mode.The fish is propelled by undulations of a long-based dorsal fin while the body axis is in many cases held straight in swimming.In order to investigate the undulatory dorsal fin propulsion and its potential for providing alternative approaches for future underwater vehicle design,the kinematics of steady forward swimming of gymnarchus niloticus was described and the geometric features of the body and locomotive characteristic and parameters of the flexible dorsal fin were discussed.Furthermore,a simplified kinematic model on locomotion of the undulatory long dorsal fin propulsion was established according to the observation and experimental data.By applying the large-amplitude elongated-body theory,the estimation shows that the hydromechanical efficiency of the undulatory long dorsal fin system is more than 83.12%.It is suggested that the undulatory long dorsal fin propulsion is an adaptation to swimming with high hydromechanical efficiency.