Thermal Performance of a Radially Rotating Twin-Pass Smooth-Walled Parallelogram Channel

An experimental study was performed to measure the detailed heat transfer distributions, Fanning friction factors (f), and thermal performance factors (TPF) of a radially rotating twin-pass parallelogram channel. Laboratory scale full field Nusselt number (Nu) distributions over leading endwall (Leading-E), and trailing endwall (Trailing-E) of the rotating channel are measured at the test conditions of 5000 < Re < 20,000, 0 < Ro < 0.3 and 0.028 < Δρ/ρ < 0.12. A selection of Nu data illustrates the individual and interactive impacts of Re, Ro, and buoyancy (Bu) numbers on local and area-averaged heat transfer properties. Without the additional flow complexities induced by the turbulators, the degrees of Bu impacts are significantly amplified from those developed in an enhanced rotating ribbed channel. Relative to the similar rotating square twin-pass channel, the heat transfer recovery over the stable wall proceeds at the lower Ro for present rotating parallelogram channel. Accompanying with the improved heat transfer performances from the square-channel counterparts, the f values are raised. With a set of f correlations generated using the f data collected from the Leading-S and Trailing-S at isothermal conditions; the TPF values at various rotating conditions were evaluated. The heat transfer correlations that determine the area-averaged Nusselt numbers over the inlet and outlet legs and over the turning region are generated. The area-averaged Nu, f factors, and TPF determined from the present rotating parallelogram channel are compared with those reported for the rotating twin-pass channels to determine the comparatively thermal performances of the parallelogram rotating channel for turbine rotor blade cooling.