Detailed mass transfer distribution in a ribbed coolant passage

Document Type

Conference Proceeding

Publication Date

12-1-1996

Abstract

Detailed, three dimensional mass (heat) transfer distributions along four active walls of a square duct containing a sharp 180° bend are presented. The duct simulates two passes of an internal coolant channel in a gas turbine engine with inactive (insulated) ribs. Mass (heat) transfer measurements, taken using the naphthalene sublimation technique, are presented for Reynolds numbers between 5000 and 40000, for a rib-height-to-hydraulic-diameter ratio (e/Dh) of 0.1 and rib-pitch-to-rib-height ratios (P/e) of 10.5 and 21. Detailed measurements taken near the edges of each wall show the influence of the corners of the duct. In smooth channels mass transfer near the corners is higher than that near the centerline due to three dimensional, secondary flows caused by the square duct cross-section. Ribbed wall measurements show the familiar periodically developed mass transfer after three hydraulic diameters from the entrance which agrees well with previous studies. Mass transfer distribution on ribbed walls has more span-wise uniformity than the smooth side-walls that experience high mass transfer rates close to the rib ends and near the corners downstream of each rib. The effect of the bend is more visible in the smooth duct than in the ribbed one. The observed local Sherwood number distributions are explained on the basis of the secondary flow developed within the bend and possible separation from the inner wall after the bend.

Publication Source (Journal or Book title)

American Society of Mechanical Engineers (Paper)

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