Effect of cooled turbine blade surface roughness on heat transfer rate and metal temperature in gas turbine field operations

This paper describes the effect of turbine blade surface roughness on the heat transfer rate and metal temperature in gas turbine long term field operations. The metal temperature of Ni based super-alloys can be estimated from changes in microstructure due to the aging. Applying this technology to the rotating blades used in gas turbine field operations, long term operational metal temperature were higher than during short term operation. Also, it was observed that the surface roughness of rotating blades increased during long term operations compared to new blades, which corresponds to the increase in metal temperature. The increased heat transfer rate on the rough surface of the fotating blades was predicted analytically. From these results, the relationship of the rotating turbine blade surface roughness and the increase in the metal temperature in gas turbine field operations can be estimated.