长背鳍扭波推进活鱼实验研究

Experimental study of live fish swimming by torsional wave of a dorsal fin

对依靠长背鳍扭波推进的尼罗河魔鬼鱼(GNF)进行循环水槽实验研究,录制各种游动模式的DV图像,分析研究GNF的游动参数,得到了扭波频率、波长与游速的定量关系,以及斯特罗哈数与雷诺数的关系曲线。当特征游速U≤1.3时,游速与扭波频率成正比,特征波长λ≈0.31,斯特罗哈数St≈0.41;当特征游速U>1.3时,扭波频率ν不再增大(约5.5～6 Hz),GNF采用变波长模式游动,平均特征波长λ最大增加到0.38,斯特罗哈数St则减小,最小为0.31,与BCF模式St值相同。

Experimental research was made of the channel flow according to the swimming of Gymnarchus niloticus fish（GNF）by the torsional wave of a dorsal fin.Some kinematic parameters of the swimming were determined by analyzing the digital video of live GNF.The curves of swimming speed U varying with the wave frequency ν and Strouhal number St varying with Reynolds number Re were presented.When the non-dimensional speed U≤1.3,U is in direct proportion to ν with non-dimensional wavelength λ≈0.31 and St≈0.41.When U1.3,the frequency ν no longer increases,and the swimming mode changes from torsional wave mode to Anguilliform body undulated mode frequently.The average value of λ increases to 0.38,while St decreases to 0.31,which is the same with the value of BCF model swimming.