Two different methods to model a point absorber wave energy converter （WEC） with direct drive linear power take-off （PTO） are proposed in the present study： the frequency domain （FD） method and the time domain ...Two different methods to model a point absorber wave energy converter （WEC） with direct drive linear power take-off （PTO） are proposed in the present study： the frequency domain （FD） method and the time domain （TD） method. In the FD analysis, the frequency response function （FRF） of the WEC device is obtained via the equation of motion, and the expressions of power capture width in regular and random waves are derived as well. In the TD modeling, based on a state space approximation of the convolution term in the motion equation, both regular wave and random wave simulations are carded out. The regular wave simulation results indicate that the state space approximation is sufficiently accurate and the capture width reaches the maximum in the vicinity of the natural frequency. In the random wave simulations, the effects of buoy size, the PTO damping and wave climate on the power capture width are discussed in detail, which leads to the conclusion that the capture widths are influenced by the natural frequency of the WEC device, peak frequency of the wave spectrum, the amplitude of FRF and PTO damping. Furthermore, the increase of the capture width is at the cost of a relatively large buoy size and PTO damping when control is not included.展开更多
流体粘度对于波浪能转换装置(Wave Energy Converter,WEC)的功率有着极大影响。通过计算流体力学(Computational Fluid Dynamics,CFD)方法,对多种点吸收式WEC模型的水动力性能进行综合研究。通过雷诺平均(Reynolds-Averaged Navier-Stok...流体粘度对于波浪能转换装置(Wave Energy Converter,WEC)的功率有着极大影响。通过计算流体力学(Computational Fluid Dynamics,CFD)方法,对多种点吸收式WEC模型的水动力性能进行综合研究。通过雷诺平均(Reynolds-Averaged Navier-Stokes,RANS)方程,采用非定常粘性数值方法计算粘性附加质量和阻尼,并将其引入势流理论频域模型,实现对WEC的粘性修正,同时在粘性修正的基础上改变WEC参数和取力器(Power Take Off,PTO)阻尼,分析其垂荡运动时的水动力性能。结果发现:随着高径比的增加,粘性效应对WEC的影响越来越小,且锥角系数越小,粘性对垂荡抑制效果越明显;适当增加淹没深度可以提高约29.4%的俘能幅值;加入对应波浪频率下PTO阻尼,能够提高约5.2%的俘能效率幅值,且会降低在较大频率下波浪俘获宽度的下降速率。展开更多
基金supported by the State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University(Grant No.GKZD010023)
文摘Two different methods to model a point absorber wave energy converter （WEC） with direct drive linear power take-off （PTO） are proposed in the present study： the frequency domain （FD） method and the time domain （TD） method. In the FD analysis, the frequency response function （FRF） of the WEC device is obtained via the equation of motion, and the expressions of power capture width in regular and random waves are derived as well. In the TD modeling, based on a state space approximation of the convolution term in the motion equation, both regular wave and random wave simulations are carded out. The regular wave simulation results indicate that the state space approximation is sufficiently accurate and the capture width reaches the maximum in the vicinity of the natural frequency. In the random wave simulations, the effects of buoy size, the PTO damping and wave climate on the power capture width are discussed in detail, which leads to the conclusion that the capture widths are influenced by the natural frequency of the WEC device, peak frequency of the wave spectrum, the amplitude of FRF and PTO damping. Furthermore, the increase of the capture width is at the cost of a relatively large buoy size and PTO damping when control is not included.
文摘流体粘度对于波浪能转换装置(Wave Energy Converter,WEC)的功率有着极大影响。通过计算流体力学(Computational Fluid Dynamics,CFD)方法,对多种点吸收式WEC模型的水动力性能进行综合研究。通过雷诺平均(Reynolds-Averaged Navier-Stokes,RANS)方程,采用非定常粘性数值方法计算粘性附加质量和阻尼,并将其引入势流理论频域模型,实现对WEC的粘性修正,同时在粘性修正的基础上改变WEC参数和取力器(Power Take Off,PTO)阻尼,分析其垂荡运动时的水动力性能。结果发现:随着高径比的增加,粘性效应对WEC的影响越来越小,且锥角系数越小,粘性对垂荡抑制效果越明显;适当增加淹没深度可以提高约29.4%的俘能幅值;加入对应波浪频率下PTO阻尼,能够提高约5.2%的俘能效率幅值,且会降低在较大频率下波浪俘获宽度的下降速率。
