Flow analysis of a rectangular channel with triangular and semi-spherical protrusions

Abstract

Thermo-flow analysis of an internal cooling channel with turbulators is carried out pertinent to gas turbine blade cooling. Two-pass rectangular channel with 180° bend is adopted to assess the effect of geometric configurations of turbulators on heat transfer enhancement and pressure drop. Two-pass rectangular channel features triangular straight turbulators having ratio of 1/8 rib height to hydraulic diameter, while semi-spherical protrusion has radius of 1/8 hydraulic diameter. Protrusions are introduced along the flow path to promote mixing of flow. Influence of Reynolds number on heat transfer rates and pressure drop is also incorporated. The Reynolds number ranges in between 19,500 and 69,000, which produce same effect of the land-based air breathing engines which operate at high air speeds. To simulate flow and thermal fields in the channel, 3-dimensional configuration of channel is adopted in numerical computations. Predictions are validated with the experimental work. It is found that by introducing triangular and semi-spherical prostrations at channel wall, heat transfer rates improves significantly while pressure drop reduces. Influence of turbulators on heat transfer enhancement becomes more apparent as the heating performance is compared to smooth channel.