Fluid flow and heat transfer around a rectangular cylinder with small inclined angle (the case of a width/height ratio of a section of 5)

Experimental studies on fluid flow and heat transfer characteristics around a rectangular cylinder at the same angle of attack were carried out for Reynolds number in the range 2500-12 800. In the experiment, width/height ratio of the cylinder was chosen as 5.0 and the angle of attack was varied over the range 0-20 degrees. For alpha = 0 degrees, the cylinder axis was aligned with the flow, the separated shear layers reattached to the top and bottom surfaces intermittently. For alpha greater than or equal to 5 degrees, the lower shear layer reattached to the lower surface. The reattached flow becomes turbulent for alpha < 15<degrees>, while the flow remains laminar for alpha > 15 degrees. A clear understanding of the local heat transfer coefficients around the cylinder can be obtained in relation with the flow characteristics. The local heat transfer coefficients on the reattachment surface and on the upper and lee surfaces can be represented by the same empirical relation, Nu = CRe2/3. The constant C decreases with increases in alpha for alpha > 5 degrees. Finally, maximum average heat transfer is achieved for a values between 0 degrees and 5 degrees. (C) 2001 Elsevier Science Inc. All rights reserved.