What Are Centrifugal Fans? How Centrifugal Fans Work?

A centrifugal fan creates pressure and air movement by a combination of centrifugal (radial) velocity and rotating (tangential) velocity. As shown in Fig. 5.1, these two effects combine to create a net velocity vector.

Principle of operation of centrifugal fan.

When the fan is enclosed in a scroll (housing) as shown in Fig. 5.2, some of the velocity pressure is converted to static pressure. The fan characteristics can be changed by changing the shape of the blade.

Typical shapes (Fig. 5.3) are forward-curved, straight radial, backward- inclined (straight or curved), and airfoil.

Centrifugal fan blade types. A. Forward curved. B. Radial. C. Backward inclined. D. Airfoil.

The geometry of the fan wheel, inlet cone, and scroll also has an effect on fan performance and efficiency. For a given wheel or diameter, as the blade gets narrower and longer, higher pressures can be generated but flow rates are reduced.

The inlet cone is shown curved (bell-mouth) to minimize air turbulence. Straight cones are also used, at the cost of some reduction in performance. The clearance between the inlet cone and the wheel shroud must be minimized for efficiency, because some air is bypassed through this opening.

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1 comment:

Fantek Axial said...

Nice Post about Centrifugal Fans. Where can i find best Centrifugal Fans manufacturers?

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