ISSN Online: 2377-424X
ISBN Print: 0-85295-345-3
International Heat Transfer Conference 10
COMBINED EFFECT OF BUOYANCY AND OF TNTERFACIAL PHENOMENA ON THE HEAT TRANSFER COEFFICIENT AT THE MELT SURFACE OF AN EB EVAPORATOR.
要約
The paper deals with a melt heated on the upper free surface by a high energy electron beam. The resulting motion in the pool is a convection driven by two forces, buoyancy and thermocapillarity. The scaling law of the Nusselt number versus both Rayleigh and Marangoni numbers is derived in the laminar case by solving the Boussinesq equations and in the turbulent case by fitting with experiments carried out in CEA-France by evaporating Cerium with a 5kW axisymmetric gun. The fitting points out a strong non linear coupling effect of buoyancy and thermocapillarity on the heat flux. A third phenomena, the cratering of the free surface due to the vapor thrust, contributes to lower bound the heat flux.