Power and noise performance assessment of a variable pitch vertical axis darrieus type wind turbine

• Published in: Journal of the Brazilian Society of Mechanical Sciences and Engineering 2021-09, Vol.43 (9), Article 437
• Main Authors: Karimian, Saeed, Rasekh, Sepehr
• Format: Article
• Language: English
• Subjects: Aerodynamics; Coefficients; Computational fluid dynamics; Engineering; Flow simulation; K-omega turbulence model; Mechanical Engineering; Noise; Noise prediction; Optimization; Performance assessment; Pitch; Pitch (inclination); Pressure distribution; Sound pressure; Stress concentration; Technical Paper; Tip speed; Turbulence models; Vertical axis wind turbines
• ISSN: 1678-5878; 1806-3691
• DOI: 10.1007/s40430-021-03103-4

In this investigation, the aerodynamic and aeroacoustic assessment for a Darrieus Vertical Axis Wind Turbine (VAWT) is presented with the aim of exploring the effects of different pitch angles. The (SST) k- ω turbulence model and Ffowcs Williams—Hawkings (FW-H) acoustic analogy method have been utilized to simulate the flow field and to predict the noise radiated from the VAWT rotor. The CFD model is being validated based on experimental data of power coefficient and sound pressure level spectrum. The instantaneous moment coefficient, pressure distribution over the blade section and sound pressure level spectrum, have been presented for several pitch angles and for various tip speed ratios (TSRs). The TSR range has been covered to discover the pitch angle effect in different operating situations. From the power performance view point, a pitch angle setting equal to −1° increases the power coefficient by 4.2 percent at optimum TSR. It is shown that in the lowest TSR, more power improvement could be obtained by changing pitch angle. It is depicted that positive pitch angles would cause degrading the power performance in VAWT, except at the very low TSR range. From noise performance view point, 1.8 dB reduction in overall sound pressure level can be achieved by setting the pitch angle equal to 1° or 3° in the low TSR range. The outcome of this study indicates the importance of utilizing a simple mechanism for changing the blade pitch angle in the VAWTs in different conditions (TSRs) to achieve more efficient operation. It is concluded that power and acoustic performances, need to be compromised specially when the geometric optimization is being desired.