The combined effect of coriolis and centrifugal buoyancy forces on internal cooling of turbine blades with modified ribs using Large Eddy Simulation (LES)

Cooling of turbine blades is necessary for longer durability and better thermal efficiency of the turbines. Turbine blade cooling is fulfilled by passing a coolant through the serpentine channel roughened with turbulators. In this work, the combined effect of the centrifugal buoyancy and the Coriolis force on heat transfer of a square duct roughened with ribs is studied using Large Eddy Simulation (LES). Simulations are carried for a Reynolds number based on bulk velocity of 20,000 with staggered square (SQ) rib, Backward step (BS) rib, and Forward step (FS) rib on the leading and trailing wall. The heat transfer performance of the square duct roughened with ribs is compared at rotation numbers Ro=0.35,0.67 and Richardson numbers Ri=0.0,12.0,28.0. The heat transfer augmentation for SQ-, BS-, and FS-ribs for Ro=0.67 and Ri=28 is 4.2%, 8.6% and 14.9%, respectively, higher than that without the effects of buoyancy. The friction coefficient for SQ-, BS-, and FS-ribs for Ro=0.67 and Ri=28 is 12.8%, 14.8% and 13.3% respectively higher than that without buoyancy.