"Axial Fan" This type has the following advantages: ① the impeller speed and the same size, with the energy of this guide vanes of the impeller pump or fan ratio obtained Vane type high. If the fluid to obtain the same energy, the pre-shaped guide vanes of the impeller diameter may be slightly smaller than the rear vane-type, small size, can reduce the weight. ② conditions change. Change the angle of attack is small, so small changes in efficiency. ③ such as guide vanes made adjustable, the operating conditions change, change inlet guide vane angle to changing conditions remained relatively high efficiency.