HEAT TRANSFER ENHANCEMENT FOR TURBINE BLADE INTERNAL COOLING

Gas turbines are used extensively for aircraft propulsion, land-based power generation, and industrial applications. The turbine inlet temperatures are far above the permissible metal temperatures. Therefore, there is a need to cool the blades for safe operation. Modem developments in turbine cooling technology play a critical role in increasing the thermal efficiency and power output of advanced gas turbine designs. Turbine blades and vanes are cooled. internally and externally. This paper focuses on heat transfer augmentation of turbine blade internal cooling. Internal cooling is typically achieved by passing the cooling air through rib-enhanced serpentine passages inside the blades. Impinging jets, pin fins and dimples are also used for enhancing internal cooling heat transfer. In the past 10 years, there has been considerable progress in turbine blade internal cooling research and this paper is emphasized on reviewing selected publications to reflect recent developments in this area. In particular, this paper focuses on the newly developed design concepts as well as the combination of existing cooling techniques for turbine airfoil internal heat transfer augmentation. Rotation effects on the turbine blade leading-edge, triangular-shaped channel, mid-chord multi-pass channel and trailing-edge, wedge-shaped channel with coolant ejection are also considered.