波能转换装置耦合振动非线性水动力特性研究

Nonlinear hydrodynamic characteristics of coupled vibration of wave energy converter

针对一种新型波能转换装置,开展非线性水动力特性研究。在势流理论基础上,考虑装置不规则外形(不对称,且水线面面积不恒定)与位置变化等非线性因素对回复力的影响,并引入Morison模型分析流体黏性的附加惯性力效应与阻力效应,建立包含主要的线性与非线性水动力、从波能捕获到转换全过程的非线性动力学模型。利用计算流体动力学法搭建数值波浪水槽,开展波能转换装置响应的准确模拟,并将数值波浪水槽与所提出的非线性动力学模型的结果对比,进行非线性水动力的效应研究和系数辨识。结果表明:传统线性模型造成对波能转换性能的过高估计,非线性水动力模型显著提高了自由衰减振荡、波浪-装置耦合响应等过程的计算精度;Morison模型系数在不同工况中是变化的,幅值响应因子的计算在共振频率附近对Morison模型系数的敏感性最高。研究结果可为准确、快捷地衡量波能转换装置性能提供指导。

Here,nonlinear hydrodynamic characteristics of a new wave energy converter were studied.On the basis of potential flow theory,considering effects of nonlinear factors,such as,irregular shape of the device including asymmetry and non-constant waterplane area as well as position change,etc.On restoring force,Morison model was introduced to analyze additional inertial force effect and resistance effect of fluid viscosity,and a nonlinear dynamic model including main linear and nonlinear hydrodynamic and the whole process from wave energy capture to conversion was established.The numerical wave tank was built by using the computational fluid dynamics(CFD)method to correctly simulate wave energy converter response.The results of numerical wave tank were compared with those of the proposed nonlinear dynamic model to do nonlinear hydrodynamic effect study and coefficient identification.The results showed that traditional linear model causes overestimation of wave energy conversion performance;the proposed nonlinear hydrodynamic model significantly improves the calculation accuracy of free attenuation oscillation,wave energy converter interaction and other processes;morison model coefficients vary under different working conditions,and the calculation of amplitude response factor is most sensitive to Morison model coefficients near resonance frequencies;the study results can provide a guidance for accurately and quickly estimating performance of wave energy converter.