Energy
P. Hedayati; A. Ramiar; N. Hedayati
Abstract
Wind energy is a prominent renewable energy source, and Vertical Axis Wind Turbines (VAWTs) offer distinct advantages, including adaptability to changing wind directions and reduced noise levels. This paper conducts a numerical investigation into the impact of flat and curved stator blades on VAWTs, ...
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Wind energy is a prominent renewable energy source, and Vertical Axis Wind Turbines (VAWTs) offer distinct advantages, including adaptability to changing wind directions and reduced noise levels. This paper conducts a numerical investigation into the impact of flat and curved stator blades on VAWTs, specifically the Savonius turbine, under 2D, viscous, turbulent, and steady flow conditions. Four stator blade configurations were examined, including no stator blades, smooth stator blades, twisted stator blades (Case A), and both blades being concave (Case B). The study reveals that curved stator blades enhance VAWT performance, with Case B exhibiting the most efficient performance. The results show pressure distribution on the turbine blades is non-uniform, with high and low-pressure zones, predominantly on the windward side. The presence of stator blades enhances pressure on all turbine blades, with Case B exhibiting the most optimal pressure distribution. Detailed observation of streamline and velocity distribution reveals improved flow lines for Case B, leading to more effective turbine blade performance. Case B consistently produces the highest turbine torque, with a maximum value of approximately 2.1 N·m achieved at Re = 15750. The torque demonstrates a positive correlation with increasing Reynolds numbers. The study further introduces a non-dimensional torque ratio analysis, where Case B attains 7.59 times higher torque than the reference case at Reynolds number 15750. The sensitivity of torque increase with respect to Reynolds number change highlights that Case B (with a slope of torque increase at around 4.5e-04) is the most responsive within the studied Reynolds number range.
Energy
A. Bozorgi; M. J. Zarei
Abstract
Noise pollution is one of the biggest problems of wind turbines, especially when these turbines are located near residential areas. In this article, the effect of blade thickness is numerically investigated on the noise pollution of an H-type Darrieus wind turbine. The flow is first simulated using the ...
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Noise pollution is one of the biggest problems of wind turbines, especially when these turbines are located near residential areas. In this article, the effect of blade thickness is numerically investigated on the noise pollution of an H-type Darrieus wind turbine. The flow is first simulated using the unsteady Reynolds averaged Navier-Stokes equations and the SST-kω model at the tip speed ratio of 2.64. Then, the noise is calculated using Ffowcs Williams-Hawkings equations. Blade thickness is changed using NACA airfoils from NACA 0008 up to NACA 0024. It is concluded that noise calculation at only one point, known as a routine method in noise investigation of wind turbines, is insufficient to investigate the noise of this turbine. Here, maximum noise in directivity is defined as the criterion of noise pollution. The results show that changing the blade profile of the benchmark turbine from NACA 0021 to NACA 0015 increases the power coefficient from 0.318 to 0.371 and reduces the maximum noise from 95.67 dB (76.35 dB) to 90.19 dB (71.01 dB) at R = 2 m (8m). For NACA 0018, the power coefficient is 0.353, and the maximum noise is 89.78 dB (70.47 dB) at R = 2 m (8m). Overall, the highest output power is for NACA 0015, and the lowest noise pollution is for NACA 0018.
