Effect of leading-edge tubercles on the hydrodynamic characteristics and wake development of tidal turbines

Abstract

This paper describes an investigation into the effect of leading-edge tubercles on turbine hydrodynamic characteristics and wake development characteristics. The hydrodynamic performance and wake velocity distribution of a modified turbine—termed Bio-turbine—are tested by a channel test. The normalized mean velocity profile obtained by the large eddy simulation (LES) method is consistent with the experimental data, which indicates that the numerical method is credible in predicting turbine performance and wake turbulence. By carefully examining the wake velocity deficit, turbulence intensity variation, and evolution of the vortex structure, it is possible to discuss how the leading-edge tubercles affect turbine performance and wake instability at various tip speed ratios (TSRs). The findings demonstrate that Bio-turbine has superior energy conversion performance at high TSRs, but the power amplitude is larger and the instability is more prominent. Furthermore, the unique structure of the blade leading edge alters the pressure distribution and flow separation behavior of the blade suction side, resulting in an enlargement of the wake recovery area. As a result, greater emphasis should be placed on the design of turbines with leading-edge tubercles.