Classification of fans

2025-07-15

Fans are indispensable equipment in various industrial fields, with extremely wide applications and large quantities. To ensure efficient operation of fans, it is essential to understand their characteristics. This chapter focuses on describing the basic knowledge of fans.

I. Classification of Ventilators

1. Classification by Airflow Direction

(1) Centrifugal ventilator

Air enters the rotating blade channel and, under the effect of centrifugal force, the gas is compressed and flows along the radial direction.

(2) Axial flow fan

Air enters the fan impeller axially and, within the rotating blade passage, flows along the axis direction. Compared to centrifugal ventilators, axial flow fans have features such as high flow rate, small volume, and low pressure head. Attention should be paid when used in environments with dust and corrosive gases.

(3) Oblique flow (mixed flow) ventilator

In the ventilator's impeller, the airflow direction lies between axial flow types, approximately along the cone surface, hence it can be called an oblique flow (mixed flow) ventilator.

This type of fan has a higher pressure coefficient than axial flow fans and a higher flow coefficient than centrifugal fans.

II. Classification by Pressure

(1) Low-pressure centrifugal ventilator