Effect of duct geometry on Wells turbine performance
S. Shaaban1 ⇑, A. Abdel Hafiz2
1
Mechanical Power Engineering Department, Faculty of Engineering, Helwan University, Cairo,
Egypt
Shaaban.sameh@yahoo.com
2Mechanical Power Engineering Department, Faculty of Engineering, Helwan University, Cairo,
Egypt
aidaahafiz2@gmail.com
Abstract
Wells turbines can represent important source of renewable energy for many countries. An
essential disadvantage of Wells turbines is their low aerodynamic efficiency and consequently
low power produced. In order to enhance the Wells turbine performance, the present research
work proposes the use of a symmetrical duct in the form of a venturi tube with turbine rotor
located at throat. The effects of duct area
ratio and duct angle are investigated in order to optimize Wells turbine performance. The turbine
performance is numerically investigated by solving the steady 3D incompressible Reynolds
Averaged Navier–Stocks equation (RANS). A substantial improve of the turbine performance is
achieved by optimizing the duct geometry. Increasing both the duct area ratio and duct angle
increase the acceleration and deceleration upstream
and downstream the rotor respectively. The accelerating flow with thinner boundary layer
thickness upstream the rotor reduces the flow separation on the rotor suction side. The
downstream diffuser reduces the interaction between tip leakage flow and blade suction side. Up
to 14% increase in turbine power and 9% increase in turbine efficiency are achieved by
optimizing the duct geometry. On other hand, a tangible delay of the turbine stall point is also
detected.
Keywords: Wells turbine, Performance, Venturi duct, CFD
Published In: Energy Conversion and Management, vol 61, sept 2012,
pp 51-58
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Effect of inlet straighteners on centrifugal fan
performance
1N.N.
1
Bayomi , 1A. Abdel Hafiz and 2A.M. Osman
Faculty of Engineering, Mataria, Helwan University, 11718 Masaken, El-Helmia,
Cairo, Egypt
aidaahafiz2@gmail.com
nnbayomi@hotmail.com
Faculty of Engineering, Shoubra, Zagazig University, Cairo, Egypt
Received 31 July 2005; accepted 30 January 2006. Available online 3 April 2006.
2
Abstract
The use of straighteners in the inlet duct of centrifugal fans is suggested
for eliminating any inlet distortion. An experimental investigation was
performed to study the effect of inlet straighteners on the performance
characteristics of centrifugal fans. Two types of straighteners were used,
circular tubes and zigzag cross section, with different lengths. Circular
tubes with different diameters have been investigated. The study was
conducted on three types of fans, namely radial, backward with exit blade
angles 60° and 75° and forward with 105° and 120°. The results confirm
that the inlet straighteners exhibit different effects on the fan performance
for the different blade angles. Accordingly, the results indicate the
selection of long circular tube straighteners with large diameter for radial
blades, long zigzag type for backward 60° blade angle and short zigzag
type for backward 75° blade angle. Generally, good improvements in
efficiency are observed for radial and backward blades on account of a
slight drop in static head. In addition, an increase in the flow margin up to
12% and a decrease in the noise level from 3 to 5 dB are indicated
compared to the free inlet condition. On the contrary, unfavorable
influences are exerted on the forward fan performance.
Keywords: Centrifugal fan; Straighteners; Noise; Distortion
Published in: Energy Conversion and Management, Vol. 47, Issues 18-19,
Nov. 2006, Pages 3307-3318
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