Hydrodynamic Performance Of Turbine Research Articles

The effects of heave motion on the performance of a floating counter-rotating type tidal turbine under wave-current interaction

Wave induced motions due to actual sea state conditions will impact the performance of floating counter-rotating type tidal turbines. The wave-current interaction is a significant factor in determining the heave motion of turbines. The present study aims at investigating the effects of heave motion on the performance of a floating counter-rotating turbine under wave-current interaction. In this study, the numerical method is used to study how the heave amplitude and frequency affect the main hydrodynamic coefficients of the turbine, including the power coefficient and thrust coefficient. The form of sliding mesh combined with overset mesh is adopted, and the heave motion of the turbine is realized by the movement of the overset mesh. The simulation results show that the heave motion has an adverse effect on the hydrodynamic performance of the counter-rotating tidal turbine. The heave motion will reduce the mean power coefficient and the mean thrust coefficient by about 9% and 5% respectively. The reduction in mean thrust and power is mainly due to less optimal rotor operation caused by the hydrodynamic effects associated with oscillating inflow. The front propeller is more susceptible to heave motion than the rear propeller. Furthermore, the effects of wave on the hydrodynamic performance of turbine are studied by changing the immersion depth of the turbine. The wave will increase the power coefficient slightly, but at the same time, also increase the probability of heave motion. The results can provide data to study motion response of floating tidal turbines under wave-current interaction and control design of the output electricity.

Numerical Predictions and Experimental Verifications for Hydrodynamic Performance of Tidal Stream Turbine

Blade element momentum (BEM) theory is used to design the tidal stream turbine in this paper. ANSYS-CFX and numeca are used to predict the hydrodynamic performance of the turbine. The power coefficient of the turbine obtained by CFD is 39.36% at the design tip speed ratio. A 300mm diameter scale turbine has been built, and the tests were carried out in the circulating water channel, the power coefficient can reach 40.5% at the design tip speed ratio. Through the comparisons between experimental results and CFD results, it proves the application of the numerical method for blade design, and the distributions of the pressure and axial velocity near the blade are analyzed at the end of the paper.

Effects of Geometrical Attitude of Blade on Hydrodynamic Performance of Darrieus-type Cross-flow Water Turbine

A Darrieus-type cross-flow water turbine has been proposed by the authors for utilizing undeveloped low-head water power resources, but available data for good hydrodynamic design of it are still scanty. Here, effects of geometrical attitude of runner blade o hydrodynamic performance of turbine are investigated experimentally and discussed in comparison with theoretical results obtained by the method proposed in the preceding paper. Experimental results supported the theoretical concept that the geometrical attitude of runner blade can be specified by a single parameter, and the best efficiency was obtained when the chord line of NACA0030 aerofoil was in contact with the pitch circle tangentially at 40% chord point. Comparing the calculated results with the measured data, the geometrical attitude of blade for the best runner efficiency is identical and the shape of time variation in runner torque is similar in both the calculation and the measurement, while quantitative agreement is still insufficient.