Heat transfer enhancement by sinusoidal wavy tape insert in two-pass ribbed channels

Abstract

The turbine inlet temperature is one of the most critical parameter that determines the thermal efficiency and thrust-weight ratio of the gas turbine. However, the higher gas turbine inlet temperature significantly increases the thermal stress on the blade, which necessitates effective cooling strategy to reduce the blade temperature. In this study, a united blade cooling strategy was developed by adopting a two-pass ribbed cooling channel with wavy tape for the reason that ribs are near-wall turbulence promoters while the wavy tape is core-region promoter with relatively lower pressure-drop penalty. Ribs and wavy tape may complement each other in the cooling channel. The synergistic effect of the combined near-wall and core-region heat transfer promoter was numerically studied for Reynolds numbers from 6000 to 30000. Two key geometrical factors, namely rib to wave crest phase shift and relative wave amplitude, have significant effect on the thermal performance. The results demonstrate that wavy tape with different phase shift configurations can eliminate the lower heat transfer areas and produce more uniform heat transfer. The 0? phase shift achieved best overall thermal performance, which provided 1.07-1.08 times the flat tape heat transfer enhancement with 1.09-1.11 times the pressure drop penalty. The better heat performance is due to the secondary flow induced by wavy tape, which enhances the fluid mixing between near-wall and core-region.