Packets of Circular Cylinders

Let us consider mass and heat transfer of under a transverse flow of packets of cylinders with unstaggered chess arrangement. At sufficiently high Reynolds numbers, the tubes in the first row of a packet are in conditions close to the conditions of mass transfer for an isolated cylinder (if the gap between tubes is of the order of the cylinder radius), while the mass transfer considerably increases in the subsequent rows. This effect is produced by the fact that the first rows serve as flow turbulizers. The stabilization of mass and heat transfer is about 10% after the fourth row, and is complete after the 14th row. In what follows, we take a tube of radius a as the characteristic length, and the velocity U = Ui/ip as the characteristic flow velocity, where U[ is the flow velocity remote from the cylinder and t/ is the maximum narrowing coefficient for the packet cross-section downstream. 

The mean Sherwood number for the unstaggered packets in deep rows (for k 14, where k is the row number) is given by the formulas [254] 

For the chess arrangement of tubes in the packet, the mean Sherwood number is determined by the expressions [254] 

Mass and heat transfer in the front rows of the packet can be calculated by the approximate formula 

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