ISSN Online: 2377-424X
ISBN Print: 0-89116-559-2
International Heat Transfer Conference 8
ONSET OF THERMALLY DRIVEN SECONDARY FLOW IN HORIZONTAL RECTANGULAR DUCTS
Résumé
The laminar, three-dimensional conservation equations have been solved and supporting experiments have been performed to determine onset of thermally driven secondary flow due to bottom heating in a horizontal rectangular duct. Predictions and data were obtained for water flow in the combined and thermal entry regions for different surface thermal conditions and aspect ratios. When correlated in terms of appropriate Rayleigh and Graetz numbers and contrasted with previous data for air flow between isothermal parallel plates, the results indicate that onset of the secondary flow is approximately independent of Reynolds number, Prandtl number, aspect ratio, and whether a uniform temperature or heat flux is maintained at the bottom surface. To within the experimental uncertainty of the data, thermal stability is only slightly enhanced by the presence of a developing velocity profile.