The Design And Performance Analysis Of The Smei-submersible Tidal Current Generator With Vertical Axis Dual Rotors

As ocean renewable energy,tidal current energy has lots of advantages,such as cleanliness,wide distribution and predictability.It has become a hot research topic at home and abroad in recent years.In order to improve the technology and commercial application of tidal current enenrgy,the trend of tidal current devloment is large-scale development.However,as far as the current research status is concerned,it is basically the use of miniaturization,while the study on large-scale tidal current energy uselization is few.Based on the current research,a general design of semi submersible tidal current energy generation device with twin-vertica-turbine is proposed,which can realize the large-scale utilization of tidal current energy.A method of combining computational fluid dynamics(CFD)and three-dimensional potential flow theory is used to analyze the coupled motion response of the device in time domain under complex ocean environment loads.This paper can provide theoretical and method support for the development and design of a large floating current power station.First,the design requirements,sea conditions and reference are determined.According to the empirical formula,the main dimensions of the turbine that meet the 600 kW power and the cantilever hydraulic turbine are determined.Next,according to the main dimensions of the turbines,the proper semi submersible platform and main dimensions are selected.The proper mooring system form and layout.Then,based on the computational fluid dynamics(CFD)method,the load of the oscillating turbine is studied.The hydraulic turbine model is established by ICEM,and the CFX software is used to calculate the model.The uniform flow motion of single rotor and double rotor turbine and the analysis of force comparison and flow field analysis under the oscillating motion of single rotor and double rotor turbine are simulated respectively.Especially for hydraulic turbines under oscillatory motion,the different oscillating frequencies,oscillating amplitudes and speed ratios are compared.The obtained results can be directly applied to the calculation of coupling responses of devices.Finally,based on the three-dimensional potential flow theory,the hydrodynamic performance of the system is studied.Through the three-dimensional potential flow theory in the frequency domain frequency domain analysis of the device,RAO,added mass and radiation damping are calculated;According to the design conditions of specific environmental load calculation,wind and current load are calculated;the calculation result of turbine CFD is fitted to hydrodynamic coefficients;added mass,radiation damping and the real-time change of the excitation force is loaded into the model by the secondary development on AQWA software.In four common conditions,the calculation results show that the device has good performance and is safe and reliable.