Enhancement of forced-convection heat transfer using turbulence promoters with clearance from the heat-transfer surface

This study is a part of a research program whose objective is to determine an optimum way of enhancing forced convection heat transfer using turbulence promoters. Effectiveness of turbulence promoters with clearance between the heat transfer surface is tested. Flow friction and heat transfer coefficient are measured at Reynolds numbers ranging from 1.5 × 104 to 9 × 104. The inclination of the rib plate used as a promoter is also varied in addition to the clearance variation. The results of performer evaluations suggest that a turbulence promoter with clearance and inclination shows a slight improvement of performance in the case where the clearance is small. A possible reason that such a type of turbulence promoter does not show much improvement in its performance characteristics may be the considerable reduction of the local heat transfer rate around the region where the separated flow reattaches.