Chapter hvac engineering Fundamentals: Part 1 Introduction

Design Procedures: Part 3
97
Figure 5.1
Principle of operation of centrifugal fan.
Figure 5.2
Cutaway view of centrifugal fan.
5.2.2
Centrifugal fans
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. 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, back-
ward-inclined (straight or curved), and airfoil.
Design Procedures: Part 3
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