Centrifugal Fan

A centrifugal fan (also blower, or squirrel-cage fan, as it looks like a hamster wheel) is a mechanical device for moving air or other gases. It has a fan wheel composed of a number of fan blades, or ribs, mounted around a hub. the hub turns on a driveshaft that passes through the fan housing. The gas enters from the side of the fan wheel, turns 90 degrees and accelerates due to centrifugal force as it flows over the fan blades and exits the fan housing. Centrifugal fan was invented by Russian military engineer Alexander Sablukov in 1832, and found its usage both in the Russian light industry (such as sugar making) and abroad.

Fan Components

The major components of a typical centrifugal fan include the fan wheel, fan housing, drive mechanism, and inlet and/or outlet dampers.

Fan dampers and Vanes

Fan dampers are used to control gas flow into and out of the centrifugal fan. They may be installed on the inlet side or on the outlet side of the fan, or both. Dampers on the outlet side impose a flow resistance that is used to control gas flow. Dampers on the inlet side (inlet vanes) are designed to control gas flow by changing the amount of gas or air admitted to the fan inlet. Inlet dampers (Inlet vanes) reduce fan energy usage due to their ability to affect the airflow pattern into the fan.

Fan Ribs

The fan wheel consists of a hub on which a number of fan blades are attached. The fan blades on the hub can be arranged in three different ways: forward-curved, backward-curved or radial.

Forward-curved blades

Forward-curved blades, as in Figure 2(a), use blades that curve in the direction of the fan wheel's rotation. These are especially sensitive to particulates. Forward-curved blades are for high flow, low pressure applications.

Straight radial blades

Radial fan blades, as in Figure 2(c), extend straight out from the hub. A radial blade fan wheel is often used on particulate-laden gas streams because it is the least sensitive to solids build-up on the blades, but it is often characterized by greater noise output. High speeds, low volumes, and high pressures are common with radial fans, and are often used in vacuum cleaners, pneumatic material conveying systems, and similar processes.

Air Compressor with Centrifugal Fan

It is made of super light structure, but the structural strength is much better than axial fan. It is provided with good dynamic balancing performance, so it is of low vibration and low noise. The pneumatic performance of the centrifugal fan is better than that of axial fan. It is all provided with lower power consumption and high efficiency. It is of stable serviceable life. It is the best choice to set it on the screw air compressor.

Backward-curved blades

Backward-curved blades, as in Figure 2(b), use blades that curve against the direction of the fan wheel's rotation. The backward curvature mimics that of an airfoil cross section and provides good operating efficiency with relatively economical construction techniques. These types of fan wheels are used in fans designed to handle gas streams with low to moderate particulate loadings. They can be easily fitted with wear protection but certain blade curvatures can be prone to solids build-up. Backward curved fans can have a high range of specific speeds but are most often used for medium specific speed applications-- high pressure, medium flow applications. Backward-curved fans are much more energy efficient than radial blade fans and so, for high power applications may be a suitable alternative to the lower cost radial bladed fan.