线翎电鳗仿生鳍水动特性研究与试验测试

Research and Experimental Test on Hydrodynamic Characteristics of Bionic Fin of Electrophorus Electrics

以线翎电鳗为仿生对象,设计一款鳍条驱动的波动长鳍,建立其运动学模型,采用SST k-ω湍流模型对三维非定常不可压缩流体的N-S方程进行求解,研究波动鳍的水动特性并分析波动鳍摆动角度、摆动频率等运动参数对波动鳍推进性能的影响。针对波动鳍需要经常贴近水底工作的情况,研究波动鳍与底面距离的变化对推进性能的影响。研究表明:在波动鳍运动时,鳍面两侧形成较为明显的反卡门涡街,从而在波动鳍的尾部形成一股射流,产生向前的推力;波动鳍的推力和横向力都随着摆动角度、摆动频率的增加而增加,但在一个时间周期内,推力的波动次数大约是横向力的2倍;波动鳍与底面距离的变化对波动鳍的推力影响很小,但当波动鳍与底面距离小于波动鳍宽度的1/5时,波动鳍的横向力明显增大。通过试验验证了数值模拟结果的正确性与合理性,该研究可为高性能波动鳍推进器的设计提供理论依据。

Taking the electriceel as a bionic object,a long undulatory fin driven by fins is designed,and its kinematic model is established.The turbulent model SST k-ωis used to solve the N-S equation of three-dimensional unsteady incompressible fluid.The hydrodynamic characteristics of undulatory fin are studied,and the effects of motion parameters such as swing angle and swing frequency of undulatory fin on the propulsion performance of undulatory fin are discussed.Considering that the undulatory fin sometimes works closing to the bottom,the influence of the distance between the undulatory fin and the bottom on the propulsion performance is studied.The results show that when the undulatory fin moves,there are vortices with opposite rotation directions on both sides,which can form an obvious anti Karman Vortex Street.Thus,a jet is formed at the tail of the undulatory fin to generate forward thrust.The thrust and lateral force of the undulatory fin increase with the increase of swing angle and swing frequency,but in a time cycle,the number of fluctuations of the thrust is about twice than that of the lateral force.The distance between the undulatory fin and the bottom has little effect on the thrust of the undulatory fin,but when the distance is less than 1/5 of the width of the undulatory fin,the lateral force of the undulatory fin increases significantly.The correctness and rationality of the numerical simulation results are verified by experiments.The study provides a theoretical basis for the design of high performance undulatory fin propeller.