压电纤维致动的仿鲤鱼尾鳍式小型推进器的摆动特性及流固耦合机理  

Oscillating Performance and Fluid-structure Interaction Mechanism of a Small Koi’s Caudal Fin-like Underwater Propulsion Actuated by MFC

作　　者：任枭荣 娄军强[1,2] 贾振 杨依领 陈特欢 孟浩锋 REN Xiaorong;LOU Junqiang;JIA Zhen;YANG Yiling;CHEN Tehuan;MENG Haofeng(College of Mechanical Engineering and Mechanics,Ningbo University,Ningbo 315211;State Key Laboratory of Industrial Control Technology,Zhejiang University,Hangzhou 310027)

机构地区：[1]宁波大学机械工程与力学学院,宁波315211 [2]浙江大学工业控制技术国家重点实验室,杭州310027

出　　处：《机械工程学报》2019年第20期214-221,230,共9页Journal of Mechanical Engineering

基　　金：国家自然科学基金(51505238,61703217,51805276);浙江省自然科学基金(LQ18E050003);浙江大学工业控制技术国家重点实验室开放课题(ICT1800390)资助项目

摘　　要：宏压电纤维复合材料(Macrofiber composite,MFC)克服了传统压电材料在韧性和脆性方面的不足,具有驱动变形大、柔韧性好且防水性好的优点,在仿生变形驱动领域具有广泛的应用前景。模仿锦鲤鱼类的形态特征和身体/尾鳍(Body or caudal fin,BCF)游动推进模式,提出了一种MFC致动的仿鲤鱼尾鳍式小型水下推进器。在峰值1000 V、频率7.5 Hz的简谐激励电压下,试验测得推进器末端水下最大摆速154.5 mm/s。采用计算流体力学(Computational fluid dynamics,CFD)分析了推进器摆动过程中周围流场分布及变化情况。仿真结果表明,推进器在稳定推进阶段产生的瞬时最大推进力和平均推进力分别为9.8m N和4.22m N,与Lighthill细长体理论一致;同时从推进器周围的周期平均流场结构中观察到了一片流速约为推进器结构最大摆速2倍的高速流场区域,且始终存在着一对对称分布、旋向相反的涡环结构沿着推进器顺流而下,因此产生一股高速水流从推进器尾部喷射而出,而推进器在高速水流的反作用力下向前推进,从而揭示了仿鲤鱼尾鳍式小型水下推进器的流固耦合特性和推进机理。Macro fiber composite(MFC)exhibits significant advantages of high actuation stress,large flexibility and excellent waterproof performance,compared with conventional piezoelectric ceramics.Thus,MFC actuators have great potentials in the applications of bio-inspired locomotion and flexible actuation.Mimicking the morphological characteristics and body or caudal fin(BCF)locomotion mode of koi fishes,a small koi’s caudal fin-like underwater propulsion is designed and fabricated.Experimental results show the maximum underwater oscillating velocity of the propulsion is 154.5 mm/s,with the Peak-to-Peak actuation of 1000 V,at 7.5 Hz.Computational fluid dynamic(CFD)analyses are conducted to investigate the flow structure caused by the oscillating propulsion.Simulation results show the mean and maximum instantaneous thrust generated by the propulsion in the stable-state are 4.22 m N and 9.8 m N,respectively,which matches well with the Lighthill’s slender body theory.A high-velocity flow region is noticed around the propulsion tip from the obtained cycle-averaged velocity fields.The maximum velocity in the region is twice of the oscillating velocity of the propulsion.A pair of counter-rotating vortices can always be observed around the center of the caudal fin elongation.Meanwhile,a jet ejects from the propulsion tip,and spreads out in the downstream direction.Accordingly,the underwater propulsion is pushed forward by the reaction force produced the pseudo-jet.As a result,the propulsion mechanisms of proposed biomimetic underwater propulsion are revealed.

关 键 词：锦鲤尾鳍 水下推进器 MFC 流固耦合 BCF推进模式 

分 类 号：TP24[自动化与计算机技术—检测技术与自动化装置] TH113[自动化与计算机技术—控制科学与工程]