Natural convection around a horizontal heated cylinder: The effects of vertical confinement

Abstract

Natural convection heat transfer from a single horizontal cylinder and a pair of vertically aligned horizontal cylinders is investigated. Surface heat transfer distributions around the circumference of the cylinders are presented for Rayleigh numbers of 2 x 10 6 , 4 x 10 6 and 6 x 10 6 and a range of cylinder spacings of 1.5, 2 and 3 diameters. With a cylinder pairing the lower cylinder is unaffected by the presence of the second cylinder; the same is true of the upper cylinder if the lower one is not heated. However, when both cylinders are heated it has been found that a plume rising from the heated lower cylinder interacts with the upper cylinder and significantly affects the surface heat transfer distribution. Spectral analysis of surface heat transfer signals has established the influence of the plume oscillations on the heat transfer. Thus, when the plume from the lower cylinder oscillates out of phase with the flow around the upper cylinder it increases the mixing and results in enhanced heat transfer.

Free convection from elliptic cylinders at small Grashof numbers

“…The transformed equations are given by Eqs. (7)- (9). The similarity solution also suggests that for small t we can expand the flow variables in the following series:…”

“…The related problems of the heated flat plate and the heated circular cylinder are well studied and some of these works include [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Synthetic and Continuous Jets Impinging on a Circular Cylinder

“…Examples of passive controls in natural convection are vertical or horizontal confinements, which were studied by Atmane et al [76] and Karim et al [77], respectively.…”

The effect of the liquid motion induced by air and vapor bubbles on heat transfer around a cylinder

“…The temperature of the cylinder surface is calculated from the heat flux and the temperature of the embedded thermocouple. The manufacturer specifies a response time of 0.05 s for the heat flux sensor and provides a calibration coefficient that has been verified in natural convection by Atmane et al [10]. The voltage across the two-thermocouple junction is amplified then digitized via a NI-6024E, 12 bits A/D acquisition board.…”