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International Journal of Rotating Machinery
Volume 2007 (2007), Article ID 72190, 11 pages
http://dx.doi.org/10.1155/2007/72190
Research Article

Effect of Aspect Ratio, Channel Orientation, Rib Pitch-to-Height Ratio, and Number of Ribbed Walls on Pressure Drop Characteristics in a Rotating Channel with Detached Ribs

Department of Mechanical Engineering, Indian Institute of Technology, Mumbai 400 076, Bombay Powai, India

Received 6 May 2006; Revised 20 September 2006; Accepted 30 October 2006

Academic Editor: Sadanari Mochizuki

Copyright © 2007 K. Arun and S. V. Prabhu. 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

The present work involves experimental investigation of the effects of aspect ratio, channel orientation angle, rib pitch-to-height ratio (P/e), and number of ribbed walls on friction factor in orthogonally rotating channel with detached ribs. The ribs are separated from the base wall to provide a small region of flow between the base wall and the ribs. Experiments have been conducted at Reynolds number ranging from 10000–17000 with rotation numbers varying from 0–0.38. Pitch-to-rib height ratios (P/e) of 5 and 10 at constant rib height-to-hydraulic diameter ratio (e/D) of 0.1 and a clearance ratio (C/e) of 0.38 are considered. The rib angle of attack with respect to mainstream flow is 90. The channel orientation at which the ribbed wall becomes trailing surface (pressure side on which the Coriolis force acts) is considered as the 0 orientation angle. For one-wall ribbed case, channel is oriented from 0 to 180 about its axis in steps of 30 to change the orientation angle. For two-wall ribbed case, the orientation angle is changed from 0 to 90 in steps of 30. Friction factors for the detached ribbed channels are compared with the corresponding attached ribbed channel. It is found that in one-wall detached ribbed channel, increase in the friction factor ratio with the orientation angle is lower for rectangular channel compared to that of square channel for both the pitch-to-rib height ratios of 5 and 10 at a given Reynolds number and rotation number. Friction factor ratios of two-wall detached ribbed rectangular channel are comparable with corresponding two-wall detached ribbed square channel both under stationary and rotating conditions.