Technical Study Of Marine Cuurrent Energy Converters Under The Yawing Angle

With the International energy crisis and the continued deterioration of the environment, many countries increase the development of renewable energy. Marine current energy is a clean and renewable energy, which is one of the most exploitable and flexible ocean energy. Utilizing the marine current technologies to generate electricity can not only improve the energy structure, reduce environment pollution and climate change due to fossil energy consumption, but also don’t need to build dams and reservoirs, the cost of investment is low.Firstly, in this paper, it generally presents the prospect of the marine current energy resources and the development of the marine current turbines based on relevant publications search and investigation, and points out that its flow direction is of uncertainty. At present, the domestic and foreign research on the marine current turbines mainly focuses on the relation between turbine blade airfoil geometric parameters and rotational speed, while the research is less how to rectify yawing angle and increase the input of the turbine and coming velocity. At the same time, when the angle between the coming flow and the blade airfoil achieves certain angle, it can appear stall, but currently there is no reliable theory to predict its stall angle, in the circumstances, when the coming flow direction is yawing, It can appear stall which makes the input of the turbine kinetic energy decrease and the output power reduce. At last,the significance and main research contents are presented of the project. Secondly, in this paper, the experimental devices of marine currents converter designed in the Hydraulics Laboratory of Zhejiang University of Technology is described, including the steel turbine blade, nylon PA12turbine blade, speeding-up inlet venturi pipe and so on. Then,the experimental investigation was carried out of the relation between the rotation speed and velocity in free flow and pressure flow situation for the nylon PA12turbine blade and the turbine blade cavitation characteristics. at different coming velocities a more systematically experimental study and analysis of yawing angle rectified by different area ratios and ldifferent lengths of speeding-up inlet and venturi pipe were conducted. At last, the corresponding numerical simulation was carried out with the change of attack angle from-4°～20°about the airfoil hydrodynamic characteristics by using the CFD commercial software called FLUENT, Pictures of the velocity contours, velocity vectors, static pressure, stall and hydrodynamic characteristics around the airfoil with the change of attack angles a were obtained, which provide references for designing efficient current converter blades. The research results of this paper can be widely used in power generation of marine current energy, which provide a broader prospect for exploring and utilizing low-velocity marine current energy.