Analytical Study of Heat Transfer from Elliptical Cylinder in Liquid Metals

摘要

Previous theoretical Nusselt numbers derived for the heat transfer to liquid metals flowing past an elliptical cylinder were based on the usual assumptions associated with inviscid potential flow. Although, in liquid metals, the thickness of the thermal boundary layer is much greater than the thickness of the hydrodynamic boundary layer, the effects of the thin hydrodynamic boundary layer on the heat transfer process cannot be neglected. In this study, the influence of a thin hydrodynamic boundary layer on the heat transfer from a single elliptical cylinder to liquid metals having low Prandtl numbers (0.001-0.03) is investigated under isothermal and isoflux boundary conditions. Two separate analytical heat transfer models, viscous and inviscid, are developed to clarify the discrepancy between previous results. It is demonstrated that the inviscid model gives higher heat transfer coefficients than the viscid model for both thermal boundary conditions, and the disagreement between the inviscid and viscous flow models originates due to the neglect of the hydrodynamic boundary layer compared to the thermal boundary layer and the effect of the separation of flow on heat transfer.