Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4994127 | International Journal of Heat and Mass Transfer | 2017 | 10 Pages |
Abstract
We present a systematic experimental study of thermal plumes within tilted turbulent thermal convection using the shadowgraph technique. The measurements are performed in a rectangular cell (aspect ratio Îx=1 and Îy=0.25) over a wide range of tilt angles (0⩽β⩽Ï/2 rad) at constant Prandtl (Prâ10) and Rayleigh (Raâ6.80Ã1010) numbers. It is found that the plume width, λ, is distributed log-normally in space and the time-averaged most probable plume width, ãλpã, has similar scale with the thermal boundary layer thickness, λT. ãλpã and λT slowly increase as tilt angle, β, increases from 0 to 1 rad and they broaden rapidly as β>1 rad. The average plume area density, ãΦã, deduced from the image intensity, is proposed to represent the heat flux of thermal plumes. Its β dependence is consistent with that of the Nusselt number, Nu, over the tilt angle range. λp and Φ exhibit oscillation of convective flow. The oscillation intensity and period strongly depend on β, but are less affected by Ra and Pr. The plume velocity exhibits a different pattern from that of the two-dimensional convective flow measured at Prâ6.3 and Raâ4.42Ã109. The magnitude of plume velocity peak is weakly affected by the cell tilting. The position of the plume velocity peak increases linearly with increasing β.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Fluid Flow and Transfer Processes
Authors
Shuang-Xi Guo, Sheng-Qi Zhou, Ling Qu, Xian-Rong Cen, Yuan-Zheng Lu,