The centrifugal fan is mainly composed of an impeller and a casing, and the impeller of a small centrifugal fan is directly mounted on the motor. Centrifugal fans are generally single-sided air intake and use single-stage impellers.

The impeller is the main component of the centrifugal fan. Its geometry, size, number of blades and manufacturing accuracy have a great influence on performance. The impeller can only ensure the stable rotation of the centrifugal fan after static balance or dynamic balance correction. According to the different direction of the blade outlet, the impeller is divided into three types: forward, radial and backward. The top of the blade of the forward impeller is inclined to the direction of rotation of the impeller; the top of the blade of the radial impeller is radial, divided into straight blade and curved blades; the top of the blade of the backward impeller is inclined in the opposite direction of the rotation of the impeller.

Radial centrifugal fan, the forward impeller produces the largest pressure. When the airflow and speed are constant, the required impeller diameter is the smallest, but the efficiency is generally low; the backward impeller is the opposite, the pressure generated is the smallest, the required impeller diameter is the largest, and the efficiency is generally higher; The radial impeller is between the two. The shape of the blade is the simplest with the straight blade, and the airfoil blade is the most complicated.

In order to have a proper velocity distribution on the blade surface, generally curved blades, such as circular arc blades of equal thickness, are generally used. The impeller usually has a cover disc to increase the strength of the impeller and reduce the gas leakage between the blade and the casing. The connection between the blade and the cover plate adopts welding or riveting. The weight of the welded impeller is lighter and the runner is smooth.

The performance parameters of centrifugal fans mainly include airflow, pressure, power, efficiency and speed. In addition, the size of noise and vibration are also the main technical indicators of centrifugal fans. Airflow, expressed by the volume of gas flowing through the centrifugal fan per unit time; Pressure refers to the increase in the pressure of the gas in the centrifugal fan, divided into static pressure, dynamic pressure and total pressure; Power refers to the input power of the centrifugal fan , that is, shaft power. The ratio of the effective power of the centrifugal fan to the shaft power is called efficiency. The total pressure efficiency of the centrifugal fan can reach 90%.

Centrifugal cooling fan, the future development of centrifugal fans will further improve the aerodynamic efficiency, device efficiency and use efficiency of centrifugal fans to reduce electrical energy consumption.