The effect of rotation on internal cooling of turbine blades with modified ribs using Large Eddy Simulation (LES)

Abstract

The cooling of the turbine blade plays a vital role in increasing the durability and thermal efficiency of the turbine. Blade cooling is achieved by passing coolant through internal channels roughened with rib turbulators. In this work, the effect of rotation on heat transfer of a square ribbed duct is studied using Large Eddy Simulation (LES) at a Reynolds number based on the average bulk velocity of 20,000. The study compares the heat transfer performance of the square duct roughened with square (SQ) rib, Backward step (BS) rib, and Forward step (FS) rib at three rotation numbers $Ro=0.18, 0.35$ and $0.67.$ In the range of rotation numbers investigated, the overall Nusselt number for SQ, BS, and FS ribs is about 14%, 20%, and 16%, respectively, higher than a non-rotating duct. The overall heat transfer augmentation factor between 3.10 and 3.25 for $0.18\le Ro\le 0.67$ in the duct with BS-ribs is approximately 24% higher than SQ-ribs, while the friction coefficient is higher only by 10–15%.