Turbulent heat transfer augmentation and friction in periodic fully developed channel flows
Abstract
Measurements are presented of the distribution of average friction factors (f) as well as local and average (Nu)bar heat transfer coefficients for fully developed channel flows with two ribroughened opposite walls. The temperature measurements were made by using both a laser holographic interferometer and thermocouples. In addition, the reattachment length was determined by flow visualization. The Reynolds number (Re) was varied from 500 to 54,000; the rib pitchtoheight ratios (Pi/H) were 10, 15, and 20; and the rib heighttohydraulic diameter ratios (H/De) were 0.063, 0.081, and 0.106. The detailed results allowed the peaks of heat transfer augmentation and the regions susceptible to hot spots to be located and allowed the relative contribution of the rib surface and the channel wall to the heat transfer augmentation to be determined. Moreover, relative to a smooth duct, the enhancement of both Nubar and f at various Re, Pi/H, and H/De was documented in detail. Furthermore, compact correlations in terms of Re, Pi/H, and H/De were developed for both Nubar and f.
 Publication:

ASME Journal of Heat Transfer
 Pub Date:
 February 1992
 Bibcode:
 1992ATJHT.114...56L
 Keywords:

 Augmentation;
 Channel Flow;
 Friction Factor;
 Heat Transfer Coefficients;
 Ribs (Supports);
 Turbulent Heat Transfer;
 Ducted Flow;
 Flow Visualization;
 Holographic Interferometry;
 Laser Interferometry;
 Nusselt Number;
 Reynolds Number;
 Temperature Measurement;
 Fluid Mechanics and Heat Transfer