HEAT TRANSFER IN ROTATING NARROW RECTANGULAR PIN-FIN DUCTS

Abstract

Abstract Rotational effects on heat transfer in radial-outflow ducts have implications for the design of gas turbine blades. The turbine blade trailing edge convective cavity generally has a narrow cross-section and often utilizes pin-fins for heat transfer enhancement. Previous research on rotational effects considered cavity shapes quite different from those of typical trailing edge cavities. In this research, experiments were conducted to determine the effect of rotation on heat transfer in pin-fin ducts of narrow cross-section (height-to-width ratio of 1:10), oriented with the heated sides at 60° to the r – z plane. In the experiment, a high-molecular-weight gas (Refrigerant-134A) at ambient pressure and temperature conditions was used to match the dimensionless parameters at engine conditions. The pin-fins were arranged in a staggered array. Thin foil heaters were used to produce a constant heat flux at the long sides of the duct; the narrow sides were unheated. Duct Reynolds numbers were varied up to 17,200; rotation numbers were varied up to 0.082. The test results show the effect of rotation on duct leading and trailing side heat transfer. In addition, the results show the variation in heat transfer coefficient with transverse location in the duct. Results are compared to data obtained for a smooth duct of identical dimensions.