Latticework (Vortex) Cooling Effectiveness: Part 2 — Rotating Channel Experiments

The heat transfer and pressure drop characteristics of latticework coolant blade passages have been investigated experimentally under conditions of rotation. Stationary studies with the latticework configuration have shown potential advantages including spatially-uniform streamwise distributions of the heat transfer coefficient, greater blade strength, and enhancement levels comparable to conventional rib turbulators. In the present study, a latticework coolant passage, with orthogonal-ribs, is studied in a rotating heat transfer test-rig for a range of Reynolds numbers (Re_s), Rotation numbers (Ro_s), and density ratios. Measurements indicate that for Re_s≥20,000, the latticework coolant passage provides very uniform streamwise distributions of the Nusselt number (Nu_s) with enhancement levels (relative to smooth-channel values) in the range of 2.0 to 2.5. No significant dependence of Nu_s on Ro_s and density ratio is observed except at lower Re_s values (≤10,000). Nusselt numbers are highest immediately downstream of a turn indicating that bend-effects play a major role in enhancing heat transfer. Friction factors are relatively insensitive to Ro_s, and thermal performance factors at higher Re_s values appear to be comparable to those obtained with conventional rib-turbulators. The present study indicates that latticework cooling geometry can provide comparable heat transfer enhancements and thermal performance factors as conventional rib-turbulators, with potential benefits of streamwise uniformity in the heat transfer coefficients and added blade strength.