Heat Transfer in Rotating Narrow Rectangular Ducts With Heated Sides Parallel to the r-z Plane

Abstract

In gas turbine blade design, a variety of channel shapes and orientations are used in the cooling circuit. Most of the rotating channel heat transfer research to date has considered channels of square or round cross-sections. This research characterizes the effect of rotation on fully developed turbulent convective heat transfer in ducts of narrow cross-section (height-to-width aspect ratio of 1:10). Experiments were conducted using ducts of narrow cross-section, oriented such that the long sides of the duct cross-section are perpendicular to the direction of blade tangential velocity (parallel to the r-z plane). In the experiment, a high-molecular-weight gas (Refrigerant-134A) at ambient pressure and temperature conditions was used to simulate coolant-to-wall density ratios that match engine conditions. Thin foil heaters were used to produce a uniform heat flux at the long sides of the duct; the narrow sides were unheated. Duct Reynolds numbers were varied up to 31,000; rotation numbers were varied up to 0.11. The test results show the effect of rotation and aspect ratio on duct leading and trailing side heat transfer. The results provide insight into the effect of rotation (Coriolis) in the absence of buoyancy effects. Comparisons with previously reported results are presented to show the effect of cross-section shape on rotating channel heat transfer.