Numerical Simulation Of Flow And Heat Transfer In A Wire-wrapped Subassembly

The demand of reliable and sustainable energy at affordable prices poses a formidablechallenge to the whole world. The initiatives from various international organizations reservean important role for liquid metal cooled fast reactor systems to resolve the problem of newand spent fuel rods. Being different from the method in pressurized water reactors （PWRs）,fuel rods were arranged triangularly to supply more heat flux considering sodium’s excellentthermal characteristics. Because the arranged method was compact, fuel rods were wrappedhelically by wires, which made the flow field very complex.. The known difficulties in heattransfer experiments, especially with liquid metals, necessitate computational fluid dynamics(CFD) to solve these problems.In the present work, simulation on liquid sodium convective flow and heat transferthrough channels with wire-wrapped rod bundles have been carried out, having similargeometric configuration to that of China Experiment Fast Reactor (CEFR). Firstly，someproblems were resolved in the modeling process of geometry and the numerical model wasestablished. Secondly simulating results were validated with data from available experimentalcorrelations for a wide range of Reynolds number to evaluate two kinds of turbulence models.Furthermore, fields of velocity, temperature and the maximum temperature on the rod surfacewere analyzed in the wire-wrapped assembly with different number of rods. Lastly, resultsfrom different wire-wraps’ structural parameters were analyzed, which illustrated the functionof wire-wraps in the whole flow field.The result predicted by specified turbulence models were nearly identical, and matchedwell with the experimental correlations. The distribution of velocity, pressure and temperaturein different wire-wrapped assemblies had a same behavior，but with the increasing number offuel rods, the flow especially the transversal flow was enhanced, meanwhile increased theevenness of the flow field. Though the most heat subassembly’s flux were loaded on the rodsurface, their maximum temperatures were not beyond the designed value. By analyzing theresult from wire-wraps’ structural parameters, it was concluded that wire-wraps play animportant role on stirring the coolant and even the temperature field.The present study have provided some references for simulation on convective flow andheat transfer of the whole wire-wrapped subassembly in the fast reactor core.