Effects of gaps between the side-walls and ribs on the heat transfer and rib induced secondary flow inside a straight rib-roughened duct

摘要

The present study investigates the effects of gaps between the side-walls and 600 ribs on the local heat transfer distribution between two consecutive ribs. The heat transfer and flow visualization experiments were carried out inside a straight rib-roughened duct with the ribs mounted on two opposite sides walls with and without the gaps. The results showed that the existence of the gaps appreciably enhances the Nu in the area between two consecutive ribs. It is caused by (1) the introduction of the fresh air through the gaps into this region and (2) the improvement of the three-dimensional flow structure in the area between two ribs.