Effects of buoyancy on heat transfer in vertical, uniformly heated channels
Research concerning the effects of buoyancy on heat transfer in vertical, uniformly heated, finite-length channels was completed. Conditions of natural and mixed convection have been studied. For the natural-convection problem, experimental and numerical results are presented for channel Rayleigh numbers extending from 1 to 10{sup 8}, far surpassing the range studied by previous investigators. Basically, this work demonstrated the importance of accounting for the effect of the acceleration of the fluid at the inlet in the laminar modeling. Additionally, a transition to turbulence, or at least, a flow with a separated boundary layer was observed for channel Rayleigh numbers greater than 10{sup 6}. The effect of buoyancy on heat transfer and fluid flow was observed through very extensive experimental studies in aiding and opposing mixed convection. Regime diagrams was established in both cases defining under what heating and external flow conditions buoyant forces are important. A significant output of the experiments includes a diagram illustrating the regions where improved heat-transfer rates can be obtained in opposing mixed convection relative to aiding mixed convection and vice versa.
- Research Organization:
- Johns Hopkins Univ., Baltimore, MD (USA)
- OSTI ID:
- 5236972
- Country of Publication:
- United States
- Language:
- English
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