Numerical Study Of ADS Liquid Windowless Spallation Target Based On Diffusion Interface Method

The Accelerate Driven Sub-critical System(ADS)consists of an accelerator,a spallation target,and a reactor.The spallation target plays an important role in coupling the accelerator and the reactor.The liquid heavy metal in the spallation target undergoes a spallation reaction with the high-energy protons emitted from the accelerator,providing a high-energy neutron source for the subcritical reactor.Therefore,the study of spallation targets is an important part of ADS system research.Liquid windowless spallation target is the current research hotspot.The working fluid forms a turbulent flow containing gas and liquid in the windowless target,and accurate prediction of the working conditions is an important part of the study of spallation targets.First,briefly introduce the numerical method of the diffusion interface method,and use water as the working fluid,based on the diffusion interface method,the four types turbulence model of k-? model,k-? model,SST model and Spalart-Allmaras model were used to perform the hydraulic numerical calculation of the ADS liquid windowless spallation target.Through grid independence verification,experimental comparison and calculation cost comparison,it is found that the k-? model is most suitable for the coupled diffusion interface method to predict the working conditions of windowless spallation targets.At the same time,the flow analysis and turbulence analysis are performed on the calculation results of the four turbulence models.The results show that the calculation results of the four turbulence models are consistent in terms of velocity field and pressure field.The velocity in the recirculation zone is lower than that of the mainstream,and the low velocity zone is dominated by the recirculation zone.The calculation results of the four turbulence models are different in the height and shape of the free interface and the length of the recirculation zone.The maximum values of turbulent kinetic energy and turbulent dissipation rate appear at the right side contour of the recirculation zone.The peak value of turbulent flow energy predicted by the SST model is the largest,and the peak value of the turbulent dissipation rate is predicted by the k-? model.But the prediction of turbulent viscosity is not obvious.In addition,these three turbulent parameters are gradually weakened as the mainstream develops downstream.Then,continue to use water as the working medium,and use the diffusion interface method and k-? model to perform detailed numerical calculation and analysis of the liquid windowless spallation target.Comparing the simulation with the experiment to prove the accuracy and reliability of the model.After performing dynamic equilibrium analysis,the flow characteristics in the target and the effects of outlet pressure and inlet velocity on the length of the free interface and the recirculation zone were studied.The results show that an elongated recirculation zone will appear in the target and a peak and valley will appear along the centerline pressure.The greater the outlet back pressure,the higher and more stable the free interface,and the smaller the length of the recirculation zone.The stability of the free interface and the continuity of the flow are very sensitive to the inlet velocity.Decreasing the inlet velocity will reduce the stability of the free interface and the continuity of the flow.Decreasing the inlet velocity will also reduce the height of the free interface and increase the length of the recirculation zoneFinally,using liquid Lead-Bismuth Eutectic as the working fluid,using the diffusion interface method and k-? model,the windowless spallation target is subjected to hydraulic numerical calculation and heat transport calculation.The effects of outlet back pressure and inlet velocity on the height of the free interface and the pressure along the way,as well as the heat transport of proton beams with different energies,were studied.The results show that with the increase of the outlet pressure,the height of the free interface of the LBE shows a linear increase law.As the inlet velocity increases,the height of the free interface of the LBE increases,and the slope of the increase decreases.The greater the outlet pressure,the greater the inlet velocity,the pressure along the cone increases.The greater the energy of the proton beam,the stronger the ability to penetrate the liquid lead-bismuth alloy,the greater the energy deposition,the larger the energy deposition range,the higher the maximum temperature,and the larger the temperature field range.