混合LES-RANS模型在结晶器钢液流场模拟中的应用
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摘要
采用了一种新的混合LES-RANS(大涡模拟-雷诺平均模型)湍流模型模拟结晶器中钢液的流场.模型通过修正湍流黏度系数对水口和结晶器内湍流进行过滤,对大尺度的湍流直接采用Navier-Stokes方程求解计算,对小尺度的脉动采用标准k-ε模型进行计算.该模型能避免RANS的过分耗散并且能捕捉到更多的瞬态湍流信息.模型通过对连铸结晶器内液态金属GaInSn模型速度进行测量验证,速度测量方法为超声波多普勒测速仪(UDV)测速法.新模型与实验测量值吻合程度明显好于RANS模拟的结果,能更准确地预测结晶器和水口内的湍流行为.结晶器内瞬态流动特征表明,水口两侧流体呈周期性的偏流,周期约为5s.
A novel hybrid LES-RANS( large eddy simulation-Reynold average Navier-Stokes) turbulent model was introduced to simulate fluid flow in a mold. The model employs the method of grid filtering which calculates the Navier-Stokes equation directly for large-scale eddies and calculates the standard k-ε equations for small-scale fluctuations by modifying the turbulent viscosity coefficient to simulate the flow field of molten steel. The modified eddy viscosity in the LES-RANS model can avoid the excessive diffusive nature of the RANS model and capture the transient features of turbulent flow. In this work,turbulent flow in a liquid metal( GaInSn) model of continuous casting was measured by ultrasonic Doppler velocimetry( UDV). It is shown that compared with the RANS model,the results of the LES-RANS model are more identical with measured data,so the LES-RANS model can more accurately predict the turbulence structure. The characteristics of transient flow in the mold show that bias flow at the two sides of the nozzle changes periodically and the period is about 5 s.
A novel hybrid LES-RANS( large eddy simulation-Reynold average Navier-Stokes) turbulent model was introduced to simulate fluid flow in a mold. The model employs the method of grid filtering which calculates the Navier-Stokes equation directly for large-scale eddies and calculates the standard k-ε equations for small-scale fluctuations by modifying the turbulent viscosity coefficient to simulate the flow field of molten steel. The modified eddy viscosity in the LES-RANS model can avoid the excessive diffusive nature of the RANS model and capture the transient features of turbulent flow. In this work,turbulent flow in a liquid metal( GaInSn) model of continuous casting was measured by ultrasonic Doppler velocimetry( UDV). It is shown that compared with the RANS model,the results of the LES-RANS model are more identical with measured data,so the LES-RANS model can more accurately predict the turbulence structure. The characteristics of transient flow in the mold show that bias flow at the two sides of the nozzle changes periodically and the period is about 5 s.
引文
[1]Liu Z Q,Li B K,Jiang M F,et al.Modeling of transient twophase flow in a continuous casting mold using Euler-Euler large eddy simulation scheme.ISIJ Int,2013,53(3):484
[2]Liu Z Q,Li B K,Jiang M F,et al.Large eddy simulation of unsteady argon-steel two phase turbulent flow in a continuous casting mold.Acta Metall Sin,2013,49(5):513(刘中秋,李宝宽,姜茂发,等.连铸结晶器内氩气/钢液两相非稳态湍流特性的大涡模拟研究.金属学报,2013,49(5):513)
[3]Thomas B G,Mika L J,Najjar F M.Simulation of fluid flow inside a continuous slab casting machine.Metall Mater Trans B,1990,21(2):387
[4]Chaudhary R,Ji C B,Thomas B G,et al.Transient turbulent flow in a liquid-metal model of continuous casting,including comparison of six different methods.Metall Mater Trans B,2011,42(5):987
[5]Ji C B,Li J S,Tang H Y,et al.Effect of EMBr on flow in slab continuous casting mold and evaluation using nail dipping measurement.Steel Res Int,2013,84(3):259
[6]Li B K,Liu Z Q,Qi F S,et al.Large eddy simulation for unsteady turbulent flow in thin slab continuous casting mold.Acta Metall Sin,2012,48(1):23(李宝宽,刘中秋,齐凤生,等.薄板坯连铸结晶器非稳态湍流大涡模拟研究.金属学报,2012,48(1):23)
[7]Cui G X,Xu C X,Zhang Z S.Progress in large eddy simulation of turbulent flows.Acta Aerodyn Sin,2004,22(2):121(崔桂香,许春晓,张兆顺.湍流大涡数值模拟进展.空气动力学学报,2004,22(2):121)
[8]Morse A P.Axisymmetric Free Shear Flows with and without Swirl[Dissertation]London:University of London,1980
[9]Johansen S T,Wu J Y,Shy W.Filter based unsteady RANS computations.Int J Heat Fluid Flow,2004,25(1):10
[10]Lilly D K.A proposed modification of the Germano subgrid-scale closure method.Phys Fluids,1992,4(3):633
[11]Cho H H,Goldstein R J.An improved low-Reynolds-number k-εturbulence model for recirculating flows.Int J Heat Mass Transfer,1994,37(10):1495
[12]Wood P E,Chen C P.Turbulence model predictions of the radial jet:a comparison of k-εmodels.Can J Chem Eng,1985,63(2):177
[13]Chen T,Liu W D,Sun M B,et al.Parametric study on the blending function in transition zone of the LES/RANS method.Chin J Theor Appl Mech,2012,44(3):487(陈逖,刘卫东,孙明波,等.LES/RANS方法混合函数特性研究.力学学报,2012,44(3):487)
[14]Abe K,Kondoh T,Nagano Y.A new turbulence model for predicting fluid flow and heat transfer in separating and reattaching flows:Ⅰ.Flow field calculations.Int J Heat Mass Transfer,1994,37(1):139
[15]Wang H Q,Bao Y P.Numerical simulation on a slab continuous casting mould.J Univ Sci Technol Beijing,2012,34(3):270(王海奇,包燕平.板坯连铸结晶器数值模拟.北京科技大学学报,2012,34(3):270)
[16]Takeda Y.Development of an ultrasound velocity profile monitor.Nucl Eng Design,1991,126(2):277
[17]Bai H,Thomas B G.Turbulent flow of liquid steel and argon bubbles in slide-gate tundish nozzles:PartⅠ.Model development and validation.Metall Mater Trans B,2001,32(2):253
[18]Ji C B,Li J S,Yang S F,et al.Large eddy simulation of turbulent fluid flow in liquid metal of continuous casting.J Iron Steel Res Int,2013,20(1):34
[2]Liu Z Q,Li B K,Jiang M F,et al.Large eddy simulation of unsteady argon-steel two phase turbulent flow in a continuous casting mold.Acta Metall Sin,2013,49(5):513(刘中秋,李宝宽,姜茂发,等.连铸结晶器内氩气/钢液两相非稳态湍流特性的大涡模拟研究.金属学报,2013,49(5):513)
[3]Thomas B G,Mika L J,Najjar F M.Simulation of fluid flow inside a continuous slab casting machine.Metall Mater Trans B,1990,21(2):387
[4]Chaudhary R,Ji C B,Thomas B G,et al.Transient turbulent flow in a liquid-metal model of continuous casting,including comparison of six different methods.Metall Mater Trans B,2011,42(5):987
[5]Ji C B,Li J S,Tang H Y,et al.Effect of EMBr on flow in slab continuous casting mold and evaluation using nail dipping measurement.Steel Res Int,2013,84(3):259
[6]Li B K,Liu Z Q,Qi F S,et al.Large eddy simulation for unsteady turbulent flow in thin slab continuous casting mold.Acta Metall Sin,2012,48(1):23(李宝宽,刘中秋,齐凤生,等.薄板坯连铸结晶器非稳态湍流大涡模拟研究.金属学报,2012,48(1):23)
[7]Cui G X,Xu C X,Zhang Z S.Progress in large eddy simulation of turbulent flows.Acta Aerodyn Sin,2004,22(2):121(崔桂香,许春晓,张兆顺.湍流大涡数值模拟进展.空气动力学学报,2004,22(2):121)
[8]Morse A P.Axisymmetric Free Shear Flows with and without Swirl[Dissertation]London:University of London,1980
[9]Johansen S T,Wu J Y,Shy W.Filter based unsteady RANS computations.Int J Heat Fluid Flow,2004,25(1):10
[10]Lilly D K.A proposed modification of the Germano subgrid-scale closure method.Phys Fluids,1992,4(3):633
[11]Cho H H,Goldstein R J.An improved low-Reynolds-number k-εturbulence model for recirculating flows.Int J Heat Mass Transfer,1994,37(10):1495
[12]Wood P E,Chen C P.Turbulence model predictions of the radial jet:a comparison of k-εmodels.Can J Chem Eng,1985,63(2):177
[13]Chen T,Liu W D,Sun M B,et al.Parametric study on the blending function in transition zone of the LES/RANS method.Chin J Theor Appl Mech,2012,44(3):487(陈逖,刘卫东,孙明波,等.LES/RANS方法混合函数特性研究.力学学报,2012,44(3):487)
[14]Abe K,Kondoh T,Nagano Y.A new turbulence model for predicting fluid flow and heat transfer in separating and reattaching flows:Ⅰ.Flow field calculations.Int J Heat Mass Transfer,1994,37(1):139
[15]Wang H Q,Bao Y P.Numerical simulation on a slab continuous casting mould.J Univ Sci Technol Beijing,2012,34(3):270(王海奇,包燕平.板坯连铸结晶器数值模拟.北京科技大学学报,2012,34(3):270)
[16]Takeda Y.Development of an ultrasound velocity profile monitor.Nucl Eng Design,1991,126(2):277
[17]Bai H,Thomas B G.Turbulent flow of liquid steel and argon bubbles in slide-gate tundish nozzles:PartⅠ.Model development and validation.Metall Mater Trans B,2001,32(2):253
[18]Ji C B,Li J S,Yang S F,et al.Large eddy simulation of turbulent fluid flow in liquid metal of continuous casting.J Iron Steel Res Int,2013,20(1):34