Performance analysis of a horizontal axis ocean current turbine with spanwise microgrooved surface

The design of turbine blade is a vital issue in the performance of horizontal axis ocean current turbine (HAOCT). The purpose of this paper is to conduct the performance analysis for HAOCT blade with spanwise microgrooved surface, including hydrodynamic analysis and hydrodynamic noise analysis. To recognize the flow around the blades, and to obtain the radiated noise of the turbines, four turbines with different configurations of microgrooved surface are tested through computational fluid dynamics (CFD) method. The hydrodynamic characteristics are obtained based on large eddy simulation (LES), then Ffowcs Williams-Hawkings (FW-H) analogy is used to predict the rotating noise generated by the HAOCT. The accuracy of the numerical predictions of flow field is checked against existing experimental data, with good agreement achieved. The results indicated that the rational design of spanwise microgrooved surface could help to reduce the annoying hydrodynamic noise. Moreover, it is shown that the microgrooved surface in blade tip region has better noise reduction effect than that in blade root region. Nevertheless, the noise reduction effect is obtained at the cost of weakening the thrust and torque at a certain degree.