Fluid Flow Analysis and Performance Prediction Of A Radial Fan Using CFD
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Date
2012-06
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Addis Ababa University
Abstract
Centrifugal fans are machine for moving a gas, such as air, by accelerating it radially
outward in an impeller to a surrounding casing. They are often used in heating and
ventilation and air condition system (HVAC). But, the efficiency of the fan can still be
improved by studying their detail performance characteristics and modifying their
geometry.
In this thesis, at first step, an experimental study is conducted to investigate the
performance characteristics of forward curved centrifugal fan by varying its volume flow
rate. From the performance characteristics of a base machine which were plotted based
on the test result, the performance of the fan increases as the flow rate of the working
fluid increases from zero to design flow rate of the fan. Beyond its design point, the
performance of the fan starts to drop. Next, a two dimensional (2D), steady state,
incompressible, turbulent flow field inside fan models have been analyzed numerically.
During numerical simulation, from all types of k-ε and k-ω turbulence models, the
appropriate turbulence model is selected based on their agreement with the experimental
result. Details of CFD analysis are done on the effects of shaft speed and blade numbers.
From the CFD analysis, a best improvement of 4.05% in efficiency has been attained at
49 blade number. But the analysis done on the shaft speed resulted in the flow rate and
outlet total pressure enhancement with direct proportion to input power and shaft speed.
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Keywords
CFD, Fluid Flow, Radial Fan, Performance Prediction