月池对振荡浮子式波能装置转换效率的影响

Effect of moonpool on the conversion efficiency of oscillating buoy wave power device

为了提高波能装置转化效率,提出了一种新的基于月池结构的振荡波能装置模型.基于势流理论,建立了振动浮体的一维频域运动方程,根据振动特性,分析了最佳弹簧刚度系数及最优输出阻尼,得到了波能装置最优效率表达式.结合复杂流场边界条件,基于特征函数展开匹配法,研究了各子域的速度势函数表达式,得到了振荡浮子的附加质量、阻尼系数及波浪激励力的表达式.为了得到月池结构对转换效率的作用并消除尖端共振带来的影响,计算了振荡圆盘在有无月池结构下的转换效率比.数值结果表明:在有效频率范围内,月池对振荡浮子获能效率有较大的提升作用;增大月池外部半径或减小内部半径时,装置低频部分有效频率范围增大,而高频部分有效频率范围上下限均发生变动.

To effectively extract and maximize the energy from ocean waves,a new kind of oscillating-body WEC(wave energy converter)with moon pool was put forward.Based on the potential flow theory,a one-dimensional frequency domain equation of motion was derived for an oscillating body.According to the vibration characteristics,the optimal spring stiffness coefficient and output damping were analyzed,and the optimal efficiency of the wave energy device was obtained.Combined with the structure characteristic of the device,using eigenfunction expansion matching method,the expressions of velocity potential function in each domain,added mass and damping coefficients and wave exciting force of the oscillating buoy were obtained.To get the effect of the moonpool on the conversion efficiency and eliminate the influence of the sharp resonance,the conversion efficiency ratio of the oscillating disc was calculated with and without moonpool.Numerical results show that in a certain frequency bandwidth,the moon pool can greatly improve the capacitation efficiency of oscillating buoy.By increasing the inner radius or decreasing the outer radius of the moonpool,the effective frequency range in the low frequency part of wave increases and the bounds of which in the higher frequency part of wave change.