Detailed velocity and turbulence measurements are shown which have been taken on a model of bayonet tube heat exchanger by means of a laser-Doppler anemometer. The heat exchanger model consists in a high aspect ratio rectangular channel with a wall provided with periodically spaced square ribs. First the fully developed flow in absence of ribs is considered for a careful analysis of the accuracy of measurements in the region close to the wall. Then the boundary layer on the flat, heat exchanging wall is deeply analyzed. The main effect of the ribs on the external wall boundary layer consists in a periodic process of relaminarization followed by transition to turbulence with no separation.
Experimental investigation of the boundary layer in a heat exchanger model equipped with square ribs
CATTANEI, ANDREA;UBALDI, MARINA;ZUNINO, PIETRO
1998-01-01
Abstract
Detailed velocity and turbulence measurements are shown which have been taken on a model of bayonet tube heat exchanger by means of a laser-Doppler anemometer. The heat exchanger model consists in a high aspect ratio rectangular channel with a wall provided with periodically spaced square ribs. First the fully developed flow in absence of ribs is considered for a careful analysis of the accuracy of measurements in the region close to the wall. Then the boundary layer on the flat, heat exchanging wall is deeply analyzed. The main effect of the ribs on the external wall boundary layer consists in a periodic process of relaminarization followed by transition to turbulence with no separation.
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