Investigation On Characteristics Of Flow And Heat Transfer In Typical 3×3 Rod Bundle Channel

The buddle fuel assemblies are widely used in nuclear reactors,and the flow and heat transfer characteristics in rod buddle channels has been a hot issue for researchers.With the continuous development of marine nuclear power platforms and nuclear-powered ships,it is undoubtedly of great theoretical significance and engineering value to study the mechanism of the influence of the inclination.In this paper,a 3×3 rod buddle channel was taken as the research object,through experimental methods.Deionized water is used to study the single-phase heat transfer and two-phase heat transfer under static conditions with different thermal conditions for the bundle channel.By selecting a suitable turbulence model,solver and discrete scheme,the numerical simulation of the single-phase flow based on the CFD method has been carried out to get the detailed analysis of the flow conditions in the rod bundle channel.The experimental study of the single-phase resistance characteristics in rod buddle channel shows that the fluid flow will turn from the laminar flow region to the transition region when the Re is around 800;The frictional resistance coefficient can be predicted by the revised Cheng & Todreas formula in the laminar or transitional region.Incline doesn't influence t frictional resistance in the rod bundle channel.The experimental study of single-phase heat transfer characteristics shows that,Under the forced circulation,the convection heat transfer can be predicted by Markoczy formula in the laminar or transitional region;for the natural circulation,the convection heat transfer can be predicted by the revised Sieder-Tate formula in the laminar flow region and the convection heat transfer can be predicted by the revised Markoczy formula in the transition flow region.Incline can increase the convection heat transfer within the rod bundle channel.The experimental study of the sub-cooled boiling heat transfer characteristics shows that,the Gengor & Winterton model can well predict the sub-cooled boiling heat transfer characteristics of the natural circulation;Incline can influence the sub-cooled boiling convection heat transfer in the rod bundle channel.The result of the numerical simulation shows that the entrance length is about 30.23 De,when Re is less than 8300,the flow in the rod bundle channel tends to be stable.The sub-channels with the highest flow velocity are the central sub-channels,the velocity in side sub-channels is lower than that in central sub-channels and the velocity in corner sub-channels is lower than that in side sub-channels.As the Re increases,the distribution of the flow velocity in different types of sub-channels tend to be uniform,and the influence of heating is similar like the Re.Due to the existence of the swaying additional force,the mixing of the adjacent sub-channels occurs which can affect the velocity distribution in different sub-channels.