  The Darrieus vertical axis wind turbines (VAWTs) are one of the mainstream
devices for wind energy utilization in the urban areas. The market's pursuit of
high wind energy conversion efficiency promotes the research on improving the
wind turbine power coefficient while reducing noise. This paper makes further
investigation on the aerodynamics and aeroacoustics of a small VAWT with
V-shaped blades and trailing-edge serrations. The feasibility of utilizing the
Reynolds-Averaged Navier-Stokes SST k-omega turbulence model and the FW-H
method is verified against experiments. The studied V-shaped blades can
effectively improve the power performance of VAWT over a wide range of tip
speed ratios under normal wind speed conditions, and the trailing-edge
serrations will also slightly increase the power output of V-bladed VAWT at the
optimal tip speed ratio. The power coefficient of the V-bladed wind turbine
with trailing-edge serrations is about 28.3% higher than that of the original
turbine. In addition, a dumbbell-shaped noise directivity distribution was
first discovered in the VAWT compared with the traditional elliptical
distribution. The V-bladed VAWT generated less low-frequency noise and the
trailing-edge serrations realized the expected noise reduction effect.
Practically, this study proposes a feasible solution for the design of
high-efficiency and low-noise wind turbines.
