考虑小攻角影响H型风轮变桨方法研究

The aerodynamic performance of the blade of lift type vertical axis wind turbine (VAWT) changes versus azimuth angle; variable pitch technology can upgrade the blade performance. Contrary to the mind of traditional variable pitch technologies, the new proposed by the paper emphasizes on the performance improvement of azimuth corresponding to small angle of attack, employs a big pitch angle in small angle of attack zone and a small pitch angle even zero in big angle of attack position, the aim of the new pitch technology is also to improve the performance of VAWT. A H-type VAWT employing NACA0012 aerofoil and 2 m height and 2 m rotation diameter is considered as research objective. Based on double disks multistream tubes model, the variation rules of angle of attack, tangential force coefficient and power density are analyzed and compared between the conditions of fixed pitch and variable pitch at tip speed ratio 5, the purpose of which is to validate the effect of the new technology. The research results showed that in the variable pitch condition, the zones with big values of angle of attack, torque coefficient and power density are amplified. The distributions of angle of attack and torque coefficient appear shapes of trapezoid in upstream disk; while in downstream disk, two new maximum points are created, the distribution of angle of attack shows shape of "W", the distribution of torque coefficient shows "M" shape.