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A combined experimental/computational study has been performed for flow in a rotating serpentine passage which approximates the internal cooling passage for turbine blades. Experimental results are presented in Part I and computational results, in Part II. Benchmark quality velocity measurements were acquired by laser-Doppler velocimetry at Reynolds number of 25,000 and Rotation number of 0.24. The results were used to assess the influence of the Coriolis force on the velocity characteristics and to explain the heat transfer phenomena observed in Wagner et al (1991). The results showed an increase in streamwise velocity on the high pressure side and a decrease in streamwise velocity on the low pressure due to Coriolis effect. Cross-stream, tangential and rms velocities indicated the presence of swirl, strong secondary flow and large turbulent fluctuations in the vicinity of the turns.

Velocity data were obtained by laser-Doppler velocimetry in rotating coolant passages with a square cross section having skewed trips. Measurements were obtained at Reynolds and Rotation numbers of 25,000 and 0.24 to quantify the influence of Coriolis effects and to explain the heat transfer phenomena observed by Johnson, et al. (1994). With rotation, outward flow and trips skewed at −45° generates counter-clockwise swirl on the high pressure side and a corner recirculation zone at the inner corner of the low pressure side. Inward flow and trips skewed at +45° generates clockwise swirl on the high pressure side and a corner recirculation zone at the upper corner of the low pressure side. The implications on heat transfer were estimated from the velocity data by the Nu-Re0.8 correlation. Johnson, et al. (1994) show that, in a passage with skewed trips, rotation increases the heat transfer from the high pressure surface of the first passage by up to 300% (relative to smooth wall stationary reference). The estimated contributions from increases in streamwise velocity, swirl and re-attachment of cross-flow in the inter-ribbed region were, respectively, 48%, <100% and >125%.

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A combined experimental/computational study has been performed for flow in rotating serpentine passages which approximate internal cooling passage for turbine blades. Experimental results are presented in the companion, Part I. The numerical simulations were performed using detailed experimental velocity profile measurements, documented in Part I, to set inflow conditions. Incompressible flow predictions with a two-layer k-ε turbulence model, which isolated the Coriolis induced secondary flow, agreed well with the measured velocities. Fluid density variations were included in compressible flow simulations which show the impact of the centrifugal buoyancy force in addition to the Coriolis force. Comparison with previously acquired heat transfer data indicates that the buoyancy force may be important in gas turbine applications.