Detailed Heat Transfer Distributions in Engine Similar Cooling Channels for a Turbine Rotor Blade With Different Rib Orientations

Detailed Nusselt number distributions are presented for a gas turbine engine similar internal channel geometry used for cooling a modern first stage rotor blade. The cooling design has one leading edge channel and a three-pass channel that covers the rest of the blade. The simulated model, generated from the midspan section of an actual cooling circuit, was studied for wall heat transfer coefficient measurements using the transient liquid crystal technique. The model wall inner surfaces were sprayed with thermochromic liquid crystals, and a transient test was used to obtain the local heat transfer coefficients from the measured color change. Results are presented for a nominal channel inlet leading edge channel Reynolds number of 10,700 and a channel inlet three-pass channel Reynolds number of 25,500. Detailed heat transfer measurements are presented for the simulated leading edge, first pass, second pass and third pass interior walls for different rib configurations. The channels were studied for smooth, 90 deg ribs, and angled ribs geometries in addition to ribs on the divider walls between adjacent passages. Overall pressure drop measurements were also obtained for each passage. Some of these results are compared with the predicted heat transfer from standard correlations used in design practices. Results show very complicated heat transfer behavior in these realistic channels compared to results obtained in simplistic geometry channels from published studies. In some cases, the Nusselt numbers predicted by correlations are 50–60% higher than obtained from the current experiments.