Heat Transfer Performances in U-Shaped Variable Cross-Section Channel with Bleeding Holes

The heat transfer distribution in U-shaped variable cross-section channels with bleeding holes was experimentally studied in the state of static. The ribs are configured in an in-line arrangement with an attack of 90 deg to the main flow. The relative roughness pitch is 25 mm, the rib width and height is 2 mm respectively. The Renault number varies from 12000 to 46000. Analysis of the experimental results may lead to the following conclusions: The heat transfer is enhanced and the flow resistance decreases with bleeding holes. The Nusselt Number of channel and cell reach to the maximum values with exit mass flow rate of 30% or so. The influence of the bleeding holes to the heat transfer is not monotone, but distributes as a conic.