How Blowers Work

Working principle of centrifugal blower [8]
The working principle of centrifugal blower is similar to that of centrifugal ventilator, except that the air compression process is usually carried out through several working impellers (or stages) under the action of centrifugal force. The blower has a high-speed rotating rotor. The blades on the rotor drive the air to move at high speed. The centrifugal force causes the air to flow along the involute line in the involute-shaped casing to the fan outlet. The high-speed airflow has a certain wind pressure. New air enters from the center of the casing to be replenished.
The working principle of a single-stage high-speed centrifugal fan is: the prime mover drives the impeller to rotate at high speed through the shaft. The airflow enters the high-speed rotating impeller axially from the inlet and becomes radial flow and is accelerated. Then it enters the diffuser cavity, changes the flow direction and decelerates. This deceleration effect converts the kinetic energy in the high-speed rotating airflow into pressure energy (potential energy), so that the fan outlet maintains a stable pressure.
Theoretically, the pressure-flow characteristic curve of a centrifugal blower is a straight line. However, due to the friction resistance and other losses inside the fan, the actual pressure-flow characteristic curve decreases gently with the increase of flow, and the corresponding power-flow curve of the centrifugal fan increases with the increase of flow. When the fan runs at a constant speed, the operating point of the fan will move along the pressure-flow characteristic curve. The operating point of the fan during operation depends not only on its own performance, but also on the characteristics of the system. When the pipe network resistance increases, the pipeline performance curve will become steeper. The basic principle of fan regulation is to obtain the desired operating conditions by changing the performance curve of the fan itself or the external pipe network characteristic curve.