A centrifugal fan is a fan in which air flows in a radi […]
A centrifugal fan is a fan in which air flows in a radial — or perpendicular — direction relative to the fan shaft. This is in contrast to axial fans, the type commonly used for household cooling, in which air flows parallel to the fan shaft. While axial fans can move large volumes of air, centrifugal fans are better suited for applications requiring high air pressure. For this reason, centrifugal fans are used in many industrial processes and in air pollution control systems.
Centrifugal fans are capable of generating relatively high pressures as the air moves outward from the impeller hub to the tips of the blade. They are often used in heavy environments that contain a high amount of moisture and particulates. The wheel is the most important component of the fan and the design determines the performance. The term squirrel cage fan and blower are often interchanged, because the configuration resembles a hamster wheel. The kinetic energy generated by the rotating blades is used to increase the pressure of the air stream, which is then used to over the resistance of the dampers, ducts and other components.
The drive mechanism of the fan may be direct, belt, or variable drive. Which drive mechanism a centrifugal fan features determines what speed the fan moves at, and how much this speed can be varied.
It's blade is a drum or circular plate configuration with blades, or ribs attached around its circumference with a space in the middle, this is called an impeller. It moves the air by pushing it down an exit duct in the fan casing at 90 degrees to the impeller itself as it rotates, air then rushes to equalise the lack of air pressure through the centre of the impeller, which is then pushed out of the duct and the cycle continues. This creates much greater air pressure, with greater efficiency.
Centrifugal fans are used in many industrial processes because they are able to produce large increases in air pressure. They are often used in grain drying and and greenhouse ventilation. These are also common in air pollution control as well as heating, ventilation and air conditioning (HVAC) systems.