Flow in a Rotating Square Serpentine Coolant Passage With Skewed Trips

Abstract

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%.