Numerical Study Of The Cavitation On The Power Efficiency Of A Vertical Axis Tidal Turbine

Because the problem of environment pollution that is caused by excessive consumption of energy is very serious recently, the Chinese government has played more attention to the clean and renewable energy resources. In this paper, as the basis of abandoned offshore platforms of Shengli Oilfield, the vertical axis turbine for tidal current energy generation is used.The vertical axis tidal turbine is very common in the power generation device. Because lots of the large projects have being implemented, all aspects of vertical tidal turbine to a higher performance are put. These comprehensive performances, including the efficiency and cavitation are the most important emphases of the vertical tidal turbine. Efficiency is linked with the utilization of energy, and cavitation is linked with the life circle of vertical tidal turbine. As a matter of fact, the two performance indicators are not independent, but both of them have closely connection. From the published research of the two areas, the field of cavitation is the less. The reasons are the complexity of the phenomenon itself. With the increment of the capacity, the dimensions of tidal turbines are quickly enlarged, and so cavitation has already become a problem that needs to be resolved now. This article uses Fluent CFD software to simulate the cavitation characteristics of the turbine, and has acquired the hydrodynamic performance of the turbine in the cavitation flow, and the cavitation flow has impact of the utilization of energy. This is the basis of the turbine design and engineering applications.Firstly, this paper conducts the force analysis on the vertical axis tidal turbine, proposes the capture efficiency as an important indicator of water turbine and then uses Fluent to simulate the tidal turbine. In order to improve the accuracy of numerical simulation, the domain size of model border is studied in detail. Fluent solver is analysed in detail and the appropriate type for the movement of the vertical tidal axis turbine is found.Secondly, in order to understand cavitation impact on the performance of turbine the paper simulates vertical axis tidal turbine in all wet flow and cavitation flow. This research focused on simulating the tidal turbine for a range of current velocities and tip speed rations. The torque and power generated by each blade and three blades were recorded as a function of azimuth angle.Finally, in the State Key Laboratory at the Dalian University of Technology, a series of experimental work on the turbine model was studied. On the one hand, the differences of the experimental model and the numerical model are analysed, focusing on analysis of the arm effect on the turbine performance; on the other hand, these result of numerical simulation in both all wet flow and t cavitation flow are compared with experimental data and the sources of these discrepancies will be discussed in more details.