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International Journal of Rotating Machinery
Volume 2011 (2011), Article ID 537824, 16 pages
http://dx.doi.org/10.1155/2011/537824
Research Article

Impeller Design of a Centrifugal Fan with Blade Optimization

1Carderock Division, Naval Surface Warfare Center, Code 5700, West Bethesda, MD 20817, USA
2Combustion Research and Flow Technology, Inc. (CRAFT Tech), Pipersville, PA 18947, USA
3Ships Systems Engineering Station, Carderock Division, Naval Surface Warfare Center, Code 9860, Philadelphia, PA 19112, USA

Received 1 December 2010; Revised 12 May 2011; Accepted 14 June 2011

Academic Editor: Meinhard Taher Schobeiri

Copyright © 2011 Yu-Tai Lee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A method is presented for redesigning a centrifugal impeller and its inlet duct. The double-discharge volute casing is a structural constraint and is maintained for its shape. The redesign effort was geared towards meeting the design volute exit pressure while reducing the power required to operate the fan. Given the high performance of the baseline impeller, the redesign adopted a high-fidelity CFD-based computational approach capable of accounting for all aerodynamic losses. The present effort utilized a numerical optimization with experiential steering techniques to redesign the fan blades, inlet duct, and shroud of the impeller. The resulting flow path modifications not only met the pressure requirement, but also reduced the fan power by 8.8% over the baseline. A refined CFD assessment of the impeller/volute coupling and the gap between the stationary duct and the rotating shroud revealed a reduction in efficiency due to the volute and the gap. The calculations verified that the new impeller matches better with the original volute. Model-fan measured data was used to validate CFD predictions and impeller design goals. The CFD results further demonstrate a Reynolds-number effect between the model- and full-scale fans.