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EnglishThe laminar mixed convection in a vertical annular duct is studied. The fully developed region is considered under the hypothesis of parallel flow. The momentum local-balance equation and the energy local-balance equation are solved analytically by means of the Fourier-series expansions method. Moreover, the Fanning friction factors are determined. Two particular cases are considered: an annular duct with the inner wall adiabatic and the outer wall subjected to a sinusoidal heat-flux distribution in the angular direction; an annulus with the inner wall subjected to a sinusoidal heat-flux distribution and the outer wall adiabatic. The threshold value of the ratio Gr/Re for the onset of the phenomenon of flow reversal is determined as a function of the duct aspect ratio. Finally, the solution for a more general case is determined: the annular duct has both walls subjected to arbitrary heat-flux distributions, which can be described as Fourier sine series with respect to the angular coordinate.
| Titolo: | Convection in a vertical annular duct with circumferentially variable boundary conditions. | |
| Autore/i: | BARLETTA, ANTONIO; LAZZARI, STEFANO; ZANCHINI, ENZO | |
| Autore/i Unibo: | ||
| Anno: | 2004 | |
| Rivista: | ||
| Digital Object Identifier (DOI): | http://dx.doi.org/10.2514/1.4293 | |
| Abstract: | The laminar mixed convection in a vertical annular duct is studied. The fully developed region is considered under the hypothesis of parallel flow. The momentum local-balance equation and the energy local-balance equation are solved analytically by means of the Fourier-series expansions method. Moreover, the Fanning friction factors are determined. Two particular cases are considered: an annular duct with the inner wall adiabatic and the outer wall subjected to a sinusoidal heat-flux distribution in the angular direction; an annulus with the inner wall subjected to a sinusoidal heat-flux distribution and the outer wall adiabatic. The threshold value of the ratio Gr/Re for the onset of the phenomenon of flow reversal is determined as a function of the duct aspect ratio. Finally, the solution for a more general case is determined: the annular duct has both walls subjected to arbitrary heat-flux distributions, which can be described as Fourier sine series with respect to the angular coordinate. | |
| Data prodotto definitivo in UGOV: | 2005-09-20 12:00:46 | |
| Appare nelle tipologie: | 1.01 Articolo in rivista |
File in questo prodotto:
http://hdl.handle.net/11585/805
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