In designing axial fans, the key is to grasp the determination of the blade outlet angle, beta 2A.
The blade can be divided into three types according to the blade outlet angle, the beta 2A, the back curved blade, the radial outlet blade and the forward curved blade.
The impeller with three blade types is now used in fan design. The characteristics of blade impeller is the size of the weight of a small, cheap, and curved blade impeller can improve the efficiency, save energy, so in the fan of modern production, especially large fan most large power with curved blades.
The fan efficiency of the modern front curved blade has been greatly improved than that of the old products, so it is still widely used in the occasions of small flow, high pressure or low pressure and large flow.
Radial outlet blades are no longer used in our country, and radial blades are often used in some kinds of fans which require abrasion resistance and corrosion resistance.
Axial flow fan impeller design must also take into account the specific speed and blade types have a certain relationship, therefore, in determining the blade outlet angle at the same time, we must consider the impact of three types of blades on the pressure, the radial size and efficiency.
The correct determination of the blade outlet angle 2A of the axial fan has laid a solid foundation for the determination of other major geometric dimensions of the impeller, thus playing a key role in the performance of the axial flow fan.