Numerical Investigations of Fluid Flow and Heat Transfer Performances of Semiattached Rib Channel Design

In order to enhance the convective heat transfer within cooling air flow channels, fully attached rib-designs have been widely used in the designs of turbine blades. To reduce the friction loss and the low heat transfer areas caused by the added ribs, permeable and detached ribs have been discussed. This work focuses on a novel rib-design, between the fully attached and detached ribs, which is therefore called semiattched rib here. To effectively reduce the low heat transfer region within the fully attached rib channel, two rectangular holes are excavated at the base of a straight rib at both concave corners of the bottom and side walls. The rest of the rib is attached to the base wall of the channel. A portion of coolant air can pass through the holes. To discuss the characteristics of the semiattached rib-designs, a numerical investigation has been performed by the commercial software Fluent 6.3, with the Reynolds number range from 10(4) to 2.5 x 10(4). The numerical results indicate that though the area-average heat transfer performances of the semiattached rib-designs are worse, the corresponding fluid flow performance are much better than both of fully attached and detached rib-designs. Another important performance is that the semiattached rib-design can fully eliminated the low heat transfer areas within the ribbed channel.