The Influence of Rotation on the Heat Transfer Characteristics of Circular, Triangular, and Square-Sectioned Coolant Passages of Gas Turbine Rotor Blades

This paper reports on the influence of Coriolis-induced secondary flow and centripetal buoyancy on the heat transfer within typical turbine rotor blade cooling passages. The experimental results indicate that for through-flow Reynolds numbers up to 30,000 increasing rotational speed tends to increase the mean levels of heat transfer relative to the stationary case when the flow is radially outward. This trend is reversed when the flow is radially inward. Increasing centripetal buoyancy for radially outward flow tends to decrease the mean level of heat transfer and in some cases these levels fall below the equivalent stationary values. When the flow is radially inward, increasing centripetal buoyancy generally results in an increase in mean heat transfer, and in this case increasing buoyancy tends to increase the leading (suction) side heat transfer while reducing it on the trailing (pressure) side. Original correlations proposed by Morris et al. for leading side heat transfer in a circular duct are shown to hold for triangular and square ducts when the hydraulic diameter concept is used.