Isolated and coupled effects of rotating and buoyancy number on heat transfer and pressure drop in a rotating two-pass parallelogram channel with transverse ribs

Detailed Nusselt number (Nu) distributions over the leading and trailing endwalls and the pressure drop coefficients (f) of a rotating transverse-ribbed two-pass parallelogram channel were measured. The impacts of Reynolds (Re), rotation (Ro) and buoyancy (Bu) numbers upon local and regionally averaged Nu over the endwall of two ribbed legs and the turn are explored for Re=5, 000-20, 000, Ro=0-0.3, and Bu=0.0015-0.122. It is aimed to study the combined buoyancy and Coriolis effects on thermal performances as the first attempt. A set of selective experimental data illustrates the isolated and interdependent Ro and Bu influences upon Nu with the impacts of Re and Ro on f disclosed. Moreover, thermal performance factors (TPF) for the channel tested are evaluated and compared with those collected from the channels with different cross-sectional shapes and endwall configurations to enlighten the relative heat transfer efficiency under rotating condition. Empirical Nu and f correlations are acquired to govern the entire Nu and f data generated. These correlations allow one to evaluate both isolated and combined Re, Ro and/or Bu impacts upon the thermal performances of the present rotating channel for internal cooling of gas turbine blades.