An Experimental Study of Turbulent Thermal Convection with Time-Dependent Volumetric Energy Sources

摘要

Turbulent natural convection in an internally heated fluid layer has recently received emphasis because of its connection with certain aspects of post-accident heat removal following a core melt accident in nuclear power reactors. Transient natural convection in a horizontal layer of dilute aqueous electrolyte with internal heat generation is experimentally investigated. The layer is bounded from below by a rigid, zero heat flux surface and from above by a rigid, isothermal surface. The nature of the developing and decaying convection processes in the layer is observed. Initially, the layer is at steady-state with power input, or Rayleigh number, greater or equal to zero. The time needed for the layer to reach its final steady-state following a step change in power input is obtained. Comparisons are made with existing experimental data for the case of a power 'on-off' step function and with an analysis based on a boundary layer approximation for the case of developing and decaying processes with initial Rayleigh number greater than zero.