Turbulent heat transfer in rotating rectangular cooling channels with angled ribs and dimples

Abstract

An investigation into determining the effect of rotation on heat transfer in smooth, rib-roughened, and dimpled rectangular channels with aspect ratio of 4:1 is detailed in this thesis. Internal cooling channels are incorporated into gas turbine blades and vanes to counter the destructive nature of extremely high combustion temperatures. The rib and dimple turbulators, appearing on the leading and trailing surface, serve to trip the boundary layer and promote mixing of the hot and cold gas regions. The effect of surface geometry and channel orientations of β=90⁰ and 135⁰ with respect to the plane of rotation are investigated. Results show that the duct orientation significantly affects the leading and side surfaces, and has less affect on the trailing surfaces for the smooth, ribbed, and dimpled surfaces. Furthermore, spanwise heat transfer distributions exist across the leading and trailing surfaces and are accentuated by the use of angled ribs. The dimpled passage exhibited spanwise variations in heat transfer for only the twisted channel orientation. The smooth, ribbed, and dimpled case trailing surfaces and smooth case side surfaces exhibited a strong dependence on rotation number.