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Abstract This paper presents an investigation on the efficiency performance of the leading-edge undulated tidal turbine blades under the effect of waves. This biomimetic blade application is inspired by humpback whale flippers which provide these mammals with an exceptional manoeuvring ability that is mainly accredited to the beneficial of their leading-edge tubercles. The paper first presents the design, optimisation and experimental validation of these turbine models. With the aim of further validating the efficiency performance in a different testing environment as well as exploring the combined effect of the tidal current and wave interaction, a test campaign in a towing tank facility was conducted. Both regular and irregular wave conditions were considered combining with varying towing speeds to simulate the tidal current effect. The test results revealed that the leading-edge undulated turbine has a stable hydrodynamic performance over a combined range of current speeds and waves indicating that the overall performance was not affected considerably by the combined effects as opposed to the performance solely due to steady tidal current. Highlights • Biomimetic concept of applying leading-edge tubercles on a tidal turbine blade has been performed. • Leading-edge tubercles have significant impacts on the improvement of the hydrodynamic performance. • First practice of testing bioinspired tidal turbine blade in a towing tank facility under the wave and current. • Power generation performance under waves were evaluated and proved the effectiveness of leading-edge tubercles under wave conditions. [ABSTRACT FROM AUTHOR]

This paper focuses on implementing detailed flow measurement using advanced Particle Image Velocimetry (PIV) system to investigate the flow mechanism of leading-edge tubercles on tidal turbine blades. Two approaches have been applied: one is 2D PIV to map the flow separation around the blade sections at different radial positions; and the other is Stereo PIV to conduct a volumetric measurement in the wake field to reveal the tip vortex development and also velocity distribution. The research presented in this paper further demonstrates that the leading-edge tubercles can enable the flow to remain attached to the blades and weaken the three dimensional effect which can lead to efficiency loss or the so-called “tip loss”. Based on these phenomena that have been observed and concluded from the tests, the mechanism by which leading-edge tubercles can provide additional torque and thrust for a tidal turbine has been explained within this paper. [ABSTRACT FROM AUTHOR]