带引流条导电矩形管磁流体湍流大涡数值模拟
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摘要
为研究引流条对磁流体湍流的影响,采用自主开发的低磁雷诺数流固耦合磁流体相干结构模型大涡模拟求解器,对均匀磁场作用下平行层内带引流条导电矩形管和标准导电矩形管中液态金属湍流进行了数值模拟研究。结果表明,外加垂直流动方向的均匀磁场与流动的导电流体相互作用产生与流动方向相反的洛伦兹力,能够抑制磁流体的湍流脉动,这种抑制作用随着哈特曼数增大而增强。在弱导电率条件下,当Re=16350、Ha=212时,两种管道中的流动均转换为层流流动状态。管道内壁面摩擦系数随着哈特曼数的增大而增大。引流条能在其近壁局部区域增强横向速度,有效激发湍流,但在弱壁面导电率条件下,带引流条导电矩形管壁面摩擦系数较标准矩形管大。
In order to investigate the effect of the flow inducing strips at wall on turbulent magnetohydrodynamic(MHD) flow, the liquid metal turbulent flow in a conducting rectangular duct with flow inducing strips at the centre of the parallel wall and in a standard conducting rectangular duct subjected to a uniform transverse magnetic field has been investigated numerically using our independently developed fluid-solid coupled MHD solver with low magnetic Reynolds number in OpenFOAM. Coherent structure model of large eddy simulation has been used in the simulation. The results show that the interaction between an external transverse uniform magnetic field and a flowing conducting fluid produces a Lorentz force opposite to the flowing direction, which can suppress the fluctuation of the turbulent flow. Furthermore, the suppressing effect is stronger with the increasing of the Hartmann number. With weak wall conductance ratio, the MHD turbulent flows in both ducts are transformed into laminar flow at Re=16350 and Ha=212. The wall friction coefficient increases with the increase of the Hartmann number. The flow inducing strips located at the centre of the parallel wall generate the transverse velocity and motivate turbulence. But its duct wall friction coefficient is a little bit higher than that in a standard rectangular duct.
In order to investigate the effect of the flow inducing strips at wall on turbulent magnetohydrodynamic(MHD) flow, the liquid metal turbulent flow in a conducting rectangular duct with flow inducing strips at the centre of the parallel wall and in a standard conducting rectangular duct subjected to a uniform transverse magnetic field has been investigated numerically using our independently developed fluid-solid coupled MHD solver with low magnetic Reynolds number in OpenFOAM. Coherent structure model of large eddy simulation has been used in the simulation. The results show that the interaction between an external transverse uniform magnetic field and a flowing conducting fluid produces a Lorentz force opposite to the flowing direction, which can suppress the fluctuation of the turbulent flow. Furthermore, the suppressing effect is stronger with the increasing of the Hartmann number. With weak wall conductance ratio, the MHD turbulent flows in both ducts are transformed into laminar flow at Re=16350 and Ha=212. The wall friction coefficient increases with the increase of the Hartmann number. The flow inducing strips located at the centre of the parallel wall generate the transverse velocity and motivate turbulence. But its duct wall friction coefficient is a little bit higher than that in a standard rectangular duct.
引文
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[2]Xu Z,Pan C,Zhang X,et al.Experimental base of an innovation S-channel to reduce MHD pressure drop[J].World Journal of Nuclear Science&Technology,2012,2(1):29-35.
[3]Mao J,Yin Y,Yu L,et al.Large eddy simulation of geometry sensitivity of magneotohydrodynamic turbulent flow in a rectangular duct[J].Fusion Eng.Des.,2018,127:111-119.
[4]Müller U,Bühler L.Magneto fluid dynamics in channels and containers[M].Springer,2001.
[5]Hunt J C R.Magnetohydrodynamic flow in rectangular ducts[J].J.Fluid Mech.,1965,21(4):577-590.
[6]Zikanov O,Krasnov D,Boeck T,et al.Laminar-turbulent transition in magnetohydrodynamic duct,pipe,and channel flows[J].Applied Mechanics Reviews,2014.66(3):030802.
[7]Kinet M,Knaepen B,Molokov S.Instabilities and transition in magnetohydrodynamic flows in ducts with electrically conducting walls[J].Phy.Rev.Lett.,2009,103(15):154501.
[8]Krasnov D,Boeck T,Braiden L,et al.Numerical simulations of MHD flow transition in ducts with conducting Hartmann walls:Limtech Project A3 D4(TUI)[M].KIT Scientific Publishing,2016.
[9]谭忠权,毛洁,刘克.磁流体管流的直接数值模拟研究[J].核聚变与等离子体物理,2016,36(4):309-314.
[10]Mao J,Zhang K,Liu K.Comparative study of different subgrid-scale models for large eddy simulations of magnetohydrodynamic turbulent duct flow in OpenFOAM[J].Computers&Fluids,2017,152:195-203.
[11]Kobayashi H.Large eddy simulation of magnetohydrodynamic turbulent duct flows[J].Phys.Fluids,2008,20(1):273-374.
[12]Kobayashi H.Large eddy simulation of magnetohydrodynamic turbulent channel flows with local subgrid-scale model based on coherent structures[J].Phys.Fluids,2006,18(4):045107.
[13]Hiromichi K,Hiroki S,Yoshihiro O.Turbulent duct flows in a liquid metal magnetohydrodynamic power generator[J].J.Fluid Mech.,2012,713:243-270.
[14]毛洁,王浩,刘克,等.基于OpenFOAM的投影法磁流体求解器开发与验证[J].核聚变与等离子体物理,2018,38(1):15-20.
[15]Ni M J,Munipalli R,Morley N B,et al.A current density conservative scheme for incompressible MHD flows at a low magnetic Reynolds number.Part I:On a rectangular collocated grid system[J].J.Comput.Phys.,2007,227(1):174-204.
[16]Ni M J,Munipalli R,Huang P,et al.A current density conservative scheme for incompressible MHD flows at a low magnetic Reynolds number.Part II:On an arbitrary collocated mesh[J].J.Comput.Phys.,2007,227(1):205-228.