Investigation of Hydrodynamic Performance and Evolution of the near Wake on a Horizontal Axis Tidal Turbine

The hydrodynamic performance and near wake of tidal current turbines are investigated via numerical simulation and experimental methods in this study. Based on large eddy simulation, the performance and wake characteristics of a tidal 10 kW turbine are then studied at different TSR (Tip Speed Ratio), and the velocity deficit and wake expansion along the flow direction are compared. The equal proportion hydraulic turbine model is designed by the similarity theory, and the experiment was carried out in a water channel, the test parameters including power and torque. The simulation and experimental results show that due to the boundary effect and blocking effect of the flume, there is a certain deviation between the experimental data and the simulation data, but the trend is the same. With the increase of TSR, the pitch of the helix formed by tip vortex gradually decreases, and the tip vortex and root vortex are destroyed earlier in the process of moving downstream. The axial velocity deficit decreases with the increase of axial distance. Finally, the hydrodynamic performance of a turbine is analyzed through experiment and simulation. The experimental results verify and support the simulation results, but there are quantitative differences, and when the TSR = 5, the turbine efficiency has the maximum value.

Automated summary

In this study, the hydrodynamic performance and near wake of tidal current turbines were investigated through numerical simulation and experimental methods. The results showed that the increase of TSR led to a decrease in the pitch of the helix formed by tip vortex and also a decrease in the axial velocity deficit. The experimental results verified the simulation results, but there were quantitative differences.