Numerical Studey Of Wave Forces On The Stationary Support Structures Of Pile Foundation For Offshore Wind Turbine

Offshore wind power industry has been growing rapidly.As estimated,the capacity of installed offshore wind turbine(OWT)in China will reach 10 GW by 2020.Compared to onshore wind turbine,the design of OWT demands more attentions on foundations and support structures.The wave loads have direct impact on the safety and reliability of the support structures.On the other hand,the scour induced by wave can also lead to the structural instability.This paper mainly focuses on the study of stationary support structures of pile foundation for OWT.A series of numerical calculations of inline wave forces on different types of OWT support structures.The details are as followed:(1)The potential flow numerical wave tank(NWT)and viscous flow NWT were coupled by the domain decomposition method.The grid independence validations of coupled NWT was presented.Also Several numerical calculations were presented to verify the feasibility of coupled model.(2)Set up the three dimensions model of stationary support structures and each one was meshed.The inline regular wave forces on the structures were calculated using coupled NWT.The support structures in this paper include monopile?multipile?cap piles and tripod/hexapod structure.(3)According to the numerical results,this paper analyzed the impact of wave parameters or the pile slope on inline wave forces for monopile structure,investigated the variation of inline wave forces on each pile in multipile structure compared to the isolated monopile cases.For the cap piles,the hydrodynamic loads on pile cap?the piles under the cap and the overall structure were proposed.Also,the change law of grouping effect induced by the phase differences among the wave force on each pile under the pile cap against the angel between wave direction and structure was discussed.For tripod/hexapod structure,the influences of wave direction angle on the forces were summarized.