Article ID Journal Published Year Pages File Type
659117 International Journal of Heat and Mass Transfer 2012 13 Pages PDF
Abstract
This paper presents an experimental investigation conducted on two evenly heated vertically arranged horizontal cylinders with a diameter of 54 mm in water. The change in Nusselt number on the upper cylinder compared to a single cylinder is presented for seven Rayleigh numbers ranging from 1.82E7 to 2.55E8 for vertical separation distances S = 1.5D, 2D, 3D, 4D, and 5D. The results show that the average Nusselt number on the upper cylinder increases for 32 out of the 35 investigated cases. A statistical description of the ensemble averaged velocity field above the upper cylinder is also presented for Rayleigh numbers 1.82E7 and 5.18E7 for S = 2D and 4D. A comparison of the buoyant plume above the upper cylinder with the plume above a single cylinder showed that the flow characteristics change considerably. The plume is significantly wider and the velocity fluctuations are about two times larger than for a single cylinder. The total kinetic energy level above the second cylinder is larger than above a single cylinder. Far downstream the plume above the second cylinder approaches a Gaussian profile associated with turbulent planar plumes.
Related Topics
Physical Sciences and Engineering Chemical Engineering Fluid Flow and Transfer Processes
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