Three-dimensional Numerical Simulation Of Wave Force On The Offshore Wind Turbine Structure And Scour Around Foundation

Recently, many countries have been paying attention to the exploitation and the utilization of wind-powered electricity generation. The offshore wind energy is 3~5 times of that on land, and the development of offshore wind turbine will become popular in the furture. However, the complex ocean environments will affect the stabilities of offshore wind turbine foundations, in which current load and wave load play an important role. Wave force on the foundations directly damage the stability of offshore wind turbine. At the same time, scour around foundations will decrease the bearing force of seabed and threaten the stability of offshore wind turbine foundations. Based on the Flow3D model, a 3D numerical wave basin is developed. The wave force on the offshore wind turbine and scour around foundations under current are examined, and the stabilities of offshore wind turbine foundations is studied.(1) A three dimensional numerical wave model which simulates the interaction of waves, current, structure and seabed, is set up based on the CFD software Flow3D, with the VOF methed to capture the free surface and the RNG k ?εmodel to simulate the turbulent fluid, the variable space step combined with outflow boundary is applied to absorbing the wave enery. It is indicated that the wave reflection on the outflow boundary is reduced efficiently and the 3D wave propagation can be simulated accurately.(2) The wave force on the pile foundation and bucket foundations under the extream wave load was simulated. Considering the effects of nearshore wave transformation, water depth is incorporated and the slope is added in order to get the design wave height near the foundations. The wave force on the foundations is simulated accurently.(3) Based on the Flow3D, a 3D numerical model for the scour around foundations under current is built. Compared with the experimental results of scour processes, the numerical results can accurately predict the depth of scour hole and the changes of bed during the erosion process around the structure to a certain extent. The established model is applied to simulate the scour process around the offshore wind turbine foundation under current, the restlt can be used for optimizing structure design.