Criteria for the Onset of Flow Recirculation and Onset of Mixed Convection in Vertical Rod Bundles

Autor: Symolon, P. D., Todreas, N. E., Rohsenow, W. M.
Zdroj: Journal of Heat Transfer; February 1987, Vol. 109 Issue: 1 p138-145, 8p
Abstrakt: In a vertical rod bundle with forced upflow and a nonuniform radial power profile, the potential for flow reversal into the low power side of the bundle exists due to buoyancy forces. In this paper a criterion is developed to predict the onset of flow recirculation in rod bundles. The criterion is validated with experimental data for flow recirculation in water-cooled bare rod bundles and with the results of a standard multichannel rod bundle code. A criterion for the onset of mixed convection is also given. Thus, the boundaries between the forced convection, mixed convection, and recirculation regimes are identified. Results are expressed on a flow regime map in terms of the dominant dimensionless parameters (the Reynolds number and a buoyancy parameter B*) and as a closed-form equation.
Databáze: Supplemental Index