Chapter hvac engineering Fundamentals: Part 1 Introduction

Design Procedures: Part 3
105
Figure 5.12
SISW centrifugal fan with overhung wheel.
Figure 5.13
DIDW centrifugal fan with wheel between bearings.
5.2.7
Axial fans
Axial-flow fans impart energy to the airstream by giving it a swirling
motion. Straightening vanes must be provided in the tubular housing
to improve flow and efficiency for use with duct systems, as shown in
Fig. 5.14. Belt or direct drive may be used. Typical performance curves
for an axial-flow fan are shown in Fig. 5.15. Note that the horsepower
increases toward the no-flow condition. Care must be taken to avoid
selection in these areas, and motors must be large enough to avoid
Design Procedures: Part 3
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