Optimum Blade Profiles for a Variable-Speed Wind Turbine in Low Wind Area

Abstract

A Blade-Element Momentum (BEM) based software was used to design a 300kW, variable speed Horizontal Axis Wind Turbine (HAWT). Chord lengths, blade twist angles and rotational speeds were allowed to change independently so as to achieve a maximum energy output, while design constraints were also being met. Computational Fluid Dynamic (CFD) was use to validated the BEM calculation. According to low wind area, the rated wind speed was set quite low at 10 m/s. The optimal design of wind turbine reaches 50.5% efficiency at the design tip speed ratio of 7.5. The wind turbine can maintain 50.5% efficiency level over wind speeds range of 4-9 m/s by changing the rotating speeds from 16-36 RPM. Beyond the rated wind speed, the turbine can regulate its power by changing the rotating speed to decrease its efficiency and maintain the power output at 300kW. Results from CFD agree well with the BEM calculation. It verifies that the optimum designed blade from the BEM was reliable.