When designing centrifugal fan, the first thing is about the selection of blade type. At a fixed speed, the pressure parameters of the backward impeller are very small, the diameter of the impeller is very large, and its speed is very high. For the forward impeller, the opposite is true. At the same time, the size of the volute of the fan should be determined, and the size of the volute should be as small as possible.
For centrifugal fans with high specific speed, the reduced worm type can be used; for low specific speed fans, the general selection criterion worm type can be used. Occasionally, in order to reduce the volume of volute and increase the volume of volute, the entrance velocity of volute is greater than the entrance velocity of fan. At this time, the entrance diffuser is used to increase the static pressure.
With regard to the selection of the pitch angle of centrifugal fan blades, in order to facilitate the application, the blades can be classified and classified as strong backward-curved blades, backward-curved circular-arc blades, backward-curved straight blades, backward-curved airfoil blades, radial vent blades, radial straight blades, Forward-curved blades, strong Forward-curved blades and other different types, which can be selected according to actual needs.
In a centrifugal fan, increasing the number of blades of the impeller can increase the theoretical pressure of the impeller, because it can reduce the effect of the corresponding undercurrent. However, the increase of the number of blades will increase the friction of the impeller line, thereby increasing energy consumption, so the number of blades of the impeller must be suitable.
The impeller is the only accessory for the fan to transmit gas energy, so its design has a great influence on the fan. Whether the important structure of the impeller can be correctly determined plays an important role in the quality coefficient of the fan.