Experimental and numerical study of developed flow and heat transfer in coolant channels with 45 degree ribs

The flow characteristics within coolant channels were investigated experime ntally and numerically to assess the current capability of Navier-Stokes co des to predict flow and heat transfer in coolant passages. The assessment w as made for developed flows in a stationary square coolant channel with opp osing square ribs staggered and angled at 45 degrees to the duct centerline , with rib heights of 10% of the channel height and with a Reynolds number of 50 000. A stereoscopic digital PIV measurement system was assembled to s imultaneously measure all three-velocity components in narrow sheets. The i nstantaneous PIV data were averaged to obtain the: three mean velocities an d the six Reynolds stresses. Velocity and heat transfer distributions were calculated for developed flow in one segment of the ribbed channels by appl ying cyclic boundary conditions. The calculations were made with three sets of wall and turbulence models: (1) a standard k-epsilon turbulence model w ith wall functions, (2) a differential-Reynolds-stress turbulence model wit h wall functions and (3) a standard k-epsilon turbulence model with a two-l ayer wall model. The comparison between the measurements and the calculatio ns showed a good qualitative agreement. The heat transfer and friction were compared to correlations for a similar configuration found in the literatu re. The comparison showed that the RSM results were more consistent with th e experimental results than the k-epsilon results with and without wall fun ctions (C) 1999 Elsevier Science Inc. All rights reserved.