非线性铰接浮体波能转换器的动力学特性研究

Dynamic characteristics of nonlinear articulated floating body wave energy converter

针对传统铰接浮体波能转换器捕获效率低、频带窄的瓶颈,提出一种新型高效波能捕获仿生非线性连接结构。该连接结构具有转动负刚度效应,可起到被动相位控制作用,提高系统的波能捕获效率。首先,基于海蛇脊柱骨结构的柔性约束机理,设计了一种高效波浪能捕获仿生连接结构,该结构由球窝结构、球头、翅状突出物和类肌肉柔性结构组成;其次,基于线性波浪理论和Cummins方程,建立两模块非线性波能转换器的动力学模型,并采用谐波平衡法解析求解非线性控制方程;最后,开展了数值模拟研究,分析了规则波激励下该新型波能转换器的波能转换特性。结果表明:通过引入新型高效仿生连接结构,可有效降低系统的等效固有频率;当连接器的负刚度结构调整到合适参数时,系统的弹性力可以在纵摇相平面上形成一个椭圆势阱,其椭圆势阱的长轴接近铰接浮体系统相对纵摇运动的模态方向,由此驱动两个模块的相对纵摇运动趋于反相,起到被动相位控制的作用。

Aiming at the bottleneck of the low capture efficiency and narrow frequency band of the traditional articulated floating body wave energy converter,this paper proposes a new high-efficiency wave energy capture bionic nonlinear connection structure.This structure has a negative stiffness effect and can play a passive phase control role to improve the wave energy capture efficiency of the system.Firstly,based on the flexible constraint mechanism of the spine bone structure of a sea snake,an efficient bionic connection structure for wave energy capture is designed,the structure consists of a ball and socket structure,ball head,winged protrusion,and muscle-like flexible structure;secondly,based on the linear wave theory and Cummins equation,the dynamic model of the two-module nonlinear wave energy converter is established.The nonlinear control equations are solved analytically by the harmonic balance method;finally,numerical simulation is carried out to analyze the wave energy conversion characteristics of the new wave energy converter under the regular wave.The results show that the equivalent natural frequency of the system can be effectively reduced by introducing a new efficient bionic connecting mechanism.When the negative stiffness structure of the connector is adjusted to appropriate parameters,the elastic force of the system will form an elliptical potential well on the pitch phase plane,and the long axis of the elliptical potential well is close to the modal direction of the relative pitch motion of the articulated floating system.Therefore,the relative pitch motion of the two driven modules tends to be anti-phase,which plays the role of passive phase control.