標題: Effects of thermal boundary condition on buoyancy driven transitional air flow in a vertical cylinder heated from below
作者: Cheng, TC
Li, YH
Lin, TF
機械工程學系
Department of Mechanical Engineering
公開日期: 1-Jun-2000
摘要: A three-dimensional unsteady numerical computation was carried out here to investigate the effects of the thermal boundary condition on the convection flow in a vertical, bottom heated cylinder containing air. The thermal condition at the sidewall of the cylinder is assumed to be thermally well insulated or perfectly conducting. Results were obtained for air in a cylinder of finite aspect ratio (Gamma = 2) for various thermal Rayleigh numbers. The predicted results indicate that the flow in the sidewall insulated cylinder is highly asymmetric even at steady state and contains multicellular vortices. The flow formation processes leading to the above structures are relatively complicated. In the early transient two axisymmetric circular vortex rolls, one on top of another, appear. Then the rods merge asymmetrically. In the late stage the flow deflection by the cylinder top and bottom results in a very complex flow. In the cylinder with a perfectly conducting sidewall the transition from a steady to a time dependent flow is subcritical. However, in the cylinder with an insulated sidewall the flow transition is supercritical.
URI: http://hdl.handle.net/11536/30484
ISSN: 1040-7782
期刊: NUMERICAL HEAT TRANSFER PART A-APPLICATIONS
Volume: 37
Issue: 8
起始頁: 917
結束頁: 936
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