Abstract
Turbulent transition mechanisms and heat transfer characteristics of natural convection over an inclined plate heated with constant heat fluxes were investigated experimentally. The experiments covered the ranges of modified Rayleigh numbers from 10^3^ to 8Γ10^12^ and inclination angles ΞΈ from 0 (horizontal) to 9^Β°^ (vertical). The flow fields over the plate were visualized with smoke. The results showed that longitudinal vortices appear first in the laminar boundary layer when ΞΈ<72^Β°^. Then, the vortices detach from the plate and become distorted, and, finally, a fully turbulent state is accomplished far downstream of the plate. Local Nusselt numbers were also measured under the same conditions as the above visualizations. The results showed that the numbers deviate from the laminar values with the formation of the longitudinal vortices and, then, increase significantly with the detachment of the vortices. Based on these results, empirical correlations for the laminar and turbulent heat transfer by natural convection were proposed. Β© 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/htj.20304