The Experimental Research On The Performance Optimization Of The Small Vertical Axis Fan Under Low Wind Speed

Wind resources are rich in our country, but in most areas the wind speed is relatively low and the wind resouces is not used effectively. Lift type vertical axis wind turbines suitable for distributed power have higher efficiency, but the performance is not ideal in low wind speed area and the start-up wind speed is high; The drag type vertical axis wind turbines have the advantage that the start-up wind speed is low, but the efficiency is low, too. Focusing on the problem above, in this article, based on the analysis of the principle of lift type and drag type fan and the research progress at home and abroad, relatively easy combined type vertical axis fan with lift type blade and drag type blade can be a key to this problem. Mainly through the method of experiment, some simple and basic exploration research, in order to improve the output power of the small vertical axis at low wind speed area by the way of the mend of drag type blade, has been done. The drag type blade used in this article is self-made by 3D printing.In the experiment of the installation way that stagger angle between drag type blade and lift type blade along the circumference, we found that semi cylinder type drag blade with the installation way that stagger angle is 60° in half radius can decrease mutual interference between lift type blade and drag type blade effectively and has the highest power output curve and optimal startup performance within the scope of the experimental wind. The reseach found that combined type vertical axis fan relies mainly on drag type blade to provide driving force under low wind speed. In the experiment to reduce interference of drag type blade to lift type blade by mending the shape of drag type blade, the efficiency increase of lift type blade cannot compensate for the efficiency loss of resistance type blade.Besides, the reseach also found that Semi elliptic cylinder blade has better streamline shape than semi cylinder drag blade, in the experiment the semi elliptic cylindrical blade can effectively improve the output performance of wind turbines. With the increase of length-diameter ratio, the output power curve shows increases at first and then decreases, but does not have self-startup ability. Semi Elliptic cylindrical blade ring installation experiment is not ideal and the turbine performance fell sharply, even in a certain angle impossible to turn.In the experiment of semi cylinder drag blade with the installation position that parallel to the front or rear and deflection, it is confirmed that the installation position that-40 mm in the rear, piror to 15°in inner side and installed in center position enhances the performance of the combined type vertical axis fan (output power and start-up ability), and the possible reason may be that the interference between lift type blade and drag type blade brings beneficial effects. In the same installation position, it is found that the turbine output power curve obviously increases with the increase of long axis of the ellipse, but a long blade will make the wind turbine losing self-starting ability.