Computational analysis of side-wall heat transfer of a turbine blade internal cooling passage with truncated ribs on opposite walls

A problem involved in the increase of the turbine inlet temperature of gas turbine engine is the failure of material because of excessive thermal stresses. This requires cooling methods to withstand the increase of the inlet temperature. Rib turbulators are often used in the mid-section of internal cooling ducts to augment the heat transfer from blade wall to the coolant. This study numerically investigates side-wall heat transfer of a rectangular passage with the leading/trailing walls being roughened by staggered ribs whose length is less than the passage width. Such a passage corresponds to the internal cooling passage near the leading edge of a turbine blade. The inlet Reynolds number is ranging from 12,000 to 60,000. The detailed 3D fluid flow and heat transfer over the side-wall are presented. The overall performances of several ribbed passages are evaluated and compared. It is found that the side-wall heat transfer coefficients of the passage with truncated (continuous) ribs on opposite walls are about 20%-27% (28%-43%) higher than those of a passage without ribs, while the pressure loss could be reduced compared to a passage with continuous ribs. It is suggested that the usage of truncated ribs is a suitable way to augment the side-wall heat transfer and improve the flow structure near the leading edge.