Noise Reduction Characteristics of Hydrofoils of Marine Current Turbines With Microgrooves on the Surface

In order to solve the serious flow noise problems of marine current turbines, a new scheme of hydrofoil with microgroove surface is proposed for noise reduction. Large eddy simulation combined with acoustic analogy of FW-H equation is applied to investigate the hydrofoils of the testing marine current turbine prototype. The results show that the numerical results are very close to the experimental results. It is found that the microgroove surface with different parameters h and N have different effects on flow noise of the hydrofoils, and the best parameters are h=0.15 mm and N=33. The mechanism of reducing flow noise using the microgroove surface is that secondary vortices are generated inside the microgrooves, which can improve the flow situation on the surface of airfoil at microgrooves. What's more, it makes the airfoil produce remarkable drag reduction and lift enhancement effect, resulting in achieving the purpose of reducing noise in the flow. Therefore, the proposed scheme with microgroove surface has a certain reference value for suppressing airfoil flow noise.