Abstract
Noise pollution from wind turbines is an important public health issue, and strict regulations regarding noise levels for nearby residents to a wind farm is a necessity. The fact that more turbines equals higher noise levels constitutes a problem, an expansion of turbines is needed but the nearby residents should not be affected. Noise levels can be measured, but, similar to other environmental attentions, the public's perception of the noise impact of wind turbines is in part a subjective determination. Vertical axis wind turbines are suitable to be established within the densely populated city area. Therefore, the noise item is very important parameter to investigate. In this work, it is introduced an innovative design of the lift VAWTs (vertical axis wind turbines) to reduce the noise emissions. Every blade in the turbine is constructed by two airfoils. The aerodynamics field of the new design have been investigated numerically to obtain the generated noise from new blades. Unsteady Reynolds-averaged Navier-Stokes (URANS) equations are used to obtain the time-accurate solutions. The spacing between the airfoils in every blade at different tip speed ratio has been studied in this work. The results indicated that the 60% spacing is the best configuration of the double-airfoil from the noise reduction point of view. This new design reduces the generated noise by 56.55% (C) 2015 Elsevier Ltd. All rights reserved.