Optimization of V-Shaped Rib Turbulators using CFD
To achieve high thermal efficiency in a gas turbine engine, the turbine inlet gas temperature should be increased.
However, the penalty is a high thermal load, which affects the durability of the turbine components. Therefore, improved
cooling techniques such as film cooling and internal cooling are applied to turbine blades. Internal cooling is achieved by
circulating low enthalpy air in multi-pass flow channels inside the blade structure. To increase the heat transfer of the
internal cooling, the internal surfaces usually are roughened by angled ribs to trip the boundary layer and increase
turbulence. A Computational Fluid Dynamics study was made to obtain heat transfer data for a single pass and two-pass
rectangular channel (aspect ratio 2:1) with smooth and ribbed surfaces for two channel orientations. The V-shaped ribs are
placed on the leading and trailing surfaces. Seven Different arrangements of 45 deg V-shaped ribs are studied. The Reynolds
numbers for study are selected as 5000 and 40000 and the rib height to hydraulic diameter ratio is 0.094, the rib pitch-toheight
ratio is 10, and the inlet coolant-to-wall density ratio is maintained around 0.115 for every test. The CFD studies are
carried out fort parallel 45 deg V-shaped rib arrangements and produce better heat transfer augmentation than inverted 45
deg V-shaped ribs and crossed 45 deg V-shaped ribs to determine the better heat transfer and augmentation of the flow. CFD
is used to predict the bulk temperature inside the duct passage from which heat transfer coefficient is arrived. Nusselt
number comparison between the various arrangements gives the insight for the enhanced heat transfer.
Index terms - CFD, RIBS ,Reynold’s Number, Duct passage, Nusselts Number, Gas Turbine