Numerical Simulation Of Magnetohydrodynamic On Duct Flows With Conducting Walls Under A Fringing Magnetic Field

Liquid metal blanket has the function of power conversion,shielding radiation and tritium breeding in the fusion reaction device.Due to the influence of magnetic field,there exists strong MHD effect,which affects the application of fusion blankets.Compared with the general hydraulics,the MHD effect results in the great MHD pressure drop,the redistribution of the velocity profile and the anisotropy of the turbulence suppression.The MHD effect is closely related to factors such as Reynolds number,Hartmann number,wall conductance ration and geometry.The study of the MHD duct flow with different physical parameters is of great reference value for the design of liquid metal blanket.Numerical simulation is an important method in the study of the MHD flow.The solution of the MHD flow at the low magnetic Reynolds number requires a highly accurate and efficient solver.MHD flow solver with low magnetic Reynolds number under the fringing magnetic field in open source CFD environment of Open FOAM have been developed.The consistent and conservative schemes based on collocated structured and unstructured grid have been applied to solve the electric potential Poisson equation,the induced electric current and the Lorentz force.The hunt's flow has been used to study the MHD laminar flow in the duct with conducting walls under the uniform magnetic field firstly.It is found that the effective range of the analytical solution is related to the flow parameters.The analytical solution is not suitable to be standard results because of the transverse velocity in the duct.Furthermore,the experiment of ALEX is simulated to validate the MHD laminar flow in the duct with conducting walls under the fringing magnetic field.The comparison between numerical simulation and experimental data shows that the solver can be used to simulate the complex flow conditions in fusion environment.The three dimensional MHD effect under fringing magnetic field is fully revealed through the simulation.The influence of the inclination angle of the magnetic field and the duct wall on the flow in the square duct is studied.The variation of the pressure distribution,the velocity profile and the current distribution has been discussed.In addition,it is also found that a laminar-turbulent transition occurs when the flow out of the magnetic field.MHD duct turbulent flow has a positive effect on heat transfer and drag reduction for the blanket.In this paper,the self-developed solver is used to study the flow characteristics of the MHD turbulent duct flow during the process of entering the magnetic field.The wall friction coefficient is calculated.The effects of different Hartmann numbers,Reynolds number and wall conductance ration on velocity profile,pressure gradient,turbulent kinetic energy,near wall flow characteristics,energy spectrum,vortex structure,three-dimensional MHD effect and wall friction coefficient are studied.