圆内开缝圆环形空间自然对流的格子Boltzmann模拟
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摘要
采用耦合热格子Boltzmann模型,对圆内开缝圆环形空间自然对流进行了数值模拟,分析了瑞利数Ra(10~4≤Ra≤10~6)和开缝度S(0.1≤S≤0.4)对环形空间内流动与换热的影响。模拟结果表明:随着瑞利数增加,环形空间内自然对流换热会出现较强的不稳定性,流型转化也较丰富,存在4种流型,稳定的二涡流、四涡流、二涡流和四涡流之间振荡的交变流以及振荡的二涡流;此外,开缝度的改变对环形空间内自然对流换热影响是显著的。随着开缝度的增大,流体更易形成多涡流型,进而增强流体扰动,流动不稳定性增强;另外,增大开缝度虽能增强环形空间内自流换热,但不是开缝度越大越好,而是存在一个最佳临界开缝度。
A coupled thermal lattice Boltzmann model was adopted to simulate the natural convection in an annulus space with an internal slotted circle. The influences of the Rayleigh number and slotted degree on the flow and heat transfer in the annulus space were discussed. The results show that, with the increase of Rayleigh number, the natural convection in the annulus space will appear strongly instable and the flow regime transition is also multiple. There are four kinds of flow patterns: steady two-eddy flow, four-eddy flow, oscillation between two-eddy and four-eddy flow and oscillatory two-eddy flow.In addition, the influence of the variation of slotted degree on the natural convective heat transfer in the annulus space is significant. With the increase of the slotted degree, the fluid is more likely to form a multi-eddy pattern's flow, which in turn increases the fluid disturbance and enhances the flow instability.The results also indicate that increasing the slotted degree can enhance the natural convective heat transfer. But the slotted degree is not the larger the better, there is a critical value.
A coupled thermal lattice Boltzmann model was adopted to simulate the natural convection in an annulus space with an internal slotted circle. The influences of the Rayleigh number and slotted degree on the flow and heat transfer in the annulus space were discussed. The results show that, with the increase of Rayleigh number, the natural convection in the annulus space will appear strongly instable and the flow regime transition is also multiple. There are four kinds of flow patterns: steady two-eddy flow, four-eddy flow, oscillation between two-eddy and four-eddy flow and oscillatory two-eddy flow.In addition, the influence of the variation of slotted degree on the natural convective heat transfer in the annulus space is significant. With the increase of the slotted degree, the fluid is more likely to form a multi-eddy pattern's flow, which in turn increases the fluid disturbance and enhances the flow instability.The results also indicate that increasing the slotted degree can enhance the natural convective heat transfer. But the slotted degree is not the larger the better, there is a critical value.
引文
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[15]黄夫泉,杨茉,余敏,等.封闭圆内开缝圆自然对流换热的振荡特性[J].工程热物理学报,2006,27(2):286-288.
[16]SHEN C Y,YANG M,ZHANG Y W,et al.Effects of slotted structures on the nonlinear characteristics of natural convection in a cylinder with an internal concentric slotted annulus[J].Numerical Heat Transfer,Part A:Applications,2016,70(5):447-459.
[17]ZHANG K,YANG M,ZHANG Y W.Two-and threedimensional numerical simulations of natural convection in a cylindrical envelope with an internal concentric cylinder with slots[J].International Journal of Heat and Mass Transfer,2014,70:434-438.
[18]ZHANG K,YANG M,WANG J,et al.Experimental study on natural convection in a cylindrical envelope with an internal concentric cylinder with slots[J].International Journal of Thermal Sciences,2014,76:190-199.
[19]YANG M,ZHOU Y W,ZHANG Y W,et al.Lattice Boltzmann method simulation of flows in cylinder with internal slotted hollow[J].Journal of Thermophysics and Heat Transfer,2014,28(2):279-286.
[20]SHI Y,ZHAO T S,GUO Z L.Finite difference-based lattice Boltzmann simulation of natural convection heat transfer in a horizontal concentric annulus[J].Computers&Fluids,2006,35(1):1-15.
[21]FATTAHI E,FARHADI M,SEDIGHI K.Lattice Boltzmann simulation of natural convection heat transfer in eccentric annulus[J].International Journal of Thermal Sciences,2010,49(12):2353-2362.
[22]LUO K,YI H L,TAN H P.Eccentricity effect on bifurcation and dual solutions in transient natural convection in a horizontal annulus[J].International Journal of Thermal Sciences,2015,89:283-293.
[23]MEHRIZI A A,FARHADI M,SHAYAMEHR S.Natural convection flow of Cu-Water nanofluid in horizontal cylindrical annuli with inner triangular cylinder using lattice Boltzmann method[J].International Communications in Heat and Mass Transfer,2013,44:147-156.
[24]GUO Z L,SHI B C,ZHENG C G.A coupled lattice BGKmodel for the Boussinesq equations[J].International Journal for Numerical Methods in Fluids,2002,39(4):325-342.
[25]GUO Z L,ZHENG C G,SHI B C.Discrete lattice effects on the forcing term in the lattice Boltzmann method[J].Physical Review E,2002,65:046308.
[26]GUO Z L,ZHENG C G,SHI B C.An extrapolation method for boundary conditions in lattice Boltzmann method[J].Physics of Fluids,2002,14(6):2007-2010.
[2]MORGAN V T.The overall convective heat transfer from smooth circular cylinders[J].Advances in Heat Transfer,1975,11:199-264.
[3]KUEHN T H,GOLDSTEIN R J.An experimental and theoretical study of natural convection in the annulus between horizontal concentric cylinders[J].Journal of Fluid Mechanics,1976,74(4):695-719.
[4]PETRONE G,CHéNIER E,LAURIAT G.Stability of free convection in air-filled horizontal annuli:influence of the radius ratio[J].International Journal of Heat and Mass Transfer,2004,47(17/18):3889-3907.
[5]PROJAHN U,RIEGER H,BEER H.Numerical analysis of laminar natural convection between concentric and eccentric cylinders[J].Numerical Heat Transfer Applications,1981,4(2):131-146.
[6]CHAO C H,CHANG K S,PARK K H.Numerical simulation of natural convection in concentric and eccentric horizontal cylindrical annuli[J].Journal of Heat Transfer,1982,104(4):624-630.
[7]DJEZZAR M,DAGUENET M.Natural steady convection in a space annulus between two elliptic confocal ducts:influence of the slope angle[J].Journal of Applied Mechanics,2006,73(1):88-95.
[8]XU X,SUN G G,YU Z T,et al.Numerical investigation of laminar natural convective heat transfer from a horizontal triangular cylinder to its concentric cylindrical enclosure[J].International Journal of Heat and Mass Transfer,2009,52(13/14):3176-3186.
[9]CIMARELLI A,ANGELI D.Routes to chaos of natural convection flows in vertical channels[J].International Communications in Heat and Mass Transfer,2017,81:201-209.
[10]GALLEGOS A D,MáLAGA C.Natural convection in eccentric spherical annuli[J].European Journal of Mechanics-B/Fluids,2017,65:464-471.
[11]KULEEK P V.Heating and cooling of busburs for large power generators[J].Electric Power Plant,1964,10:39-43.
[12]王国祥,吴清金,王启杰.双半圆大电流封闭母线自然对流换热实验研究[C]//工程热物理论文集.北京:科学出版社,1986:235-240
[13]YANG M,TAO W Q.Numerical study of natural convection heat transfer in a cylindrical envelope with internal concentric slotted hollow cylinder[J].Numerical Heat Transfer,Part A:Applications,1992,22(3):289-305.
[14]杨沫,陶文铨,杨金顺,等.圆内开缝圆环自然对流换热数值解的唯一性[J].工程热物理学报,1995,16(1):91-95.
[15]黄夫泉,杨茉,余敏,等.封闭圆内开缝圆自然对流换热的振荡特性[J].工程热物理学报,2006,27(2):286-288.
[16]SHEN C Y,YANG M,ZHANG Y W,et al.Effects of slotted structures on the nonlinear characteristics of natural convection in a cylinder with an internal concentric slotted annulus[J].Numerical Heat Transfer,Part A:Applications,2016,70(5):447-459.
[17]ZHANG K,YANG M,ZHANG Y W.Two-and threedimensional numerical simulations of natural convection in a cylindrical envelope with an internal concentric cylinder with slots[J].International Journal of Heat and Mass Transfer,2014,70:434-438.
[18]ZHANG K,YANG M,WANG J,et al.Experimental study on natural convection in a cylindrical envelope with an internal concentric cylinder with slots[J].International Journal of Thermal Sciences,2014,76:190-199.
[19]YANG M,ZHOU Y W,ZHANG Y W,et al.Lattice Boltzmann method simulation of flows in cylinder with internal slotted hollow[J].Journal of Thermophysics and Heat Transfer,2014,28(2):279-286.
[20]SHI Y,ZHAO T S,GUO Z L.Finite difference-based lattice Boltzmann simulation of natural convection heat transfer in a horizontal concentric annulus[J].Computers&Fluids,2006,35(1):1-15.
[21]FATTAHI E,FARHADI M,SEDIGHI K.Lattice Boltzmann simulation of natural convection heat transfer in eccentric annulus[J].International Journal of Thermal Sciences,2010,49(12):2353-2362.
[22]LUO K,YI H L,TAN H P.Eccentricity effect on bifurcation and dual solutions in transient natural convection in a horizontal annulus[J].International Journal of Thermal Sciences,2015,89:283-293.
[23]MEHRIZI A A,FARHADI M,SHAYAMEHR S.Natural convection flow of Cu-Water nanofluid in horizontal cylindrical annuli with inner triangular cylinder using lattice Boltzmann method[J].International Communications in Heat and Mass Transfer,2013,44:147-156.
[24]GUO Z L,SHI B C,ZHENG C G.A coupled lattice BGKmodel for the Boussinesq equations[J].International Journal for Numerical Methods in Fluids,2002,39(4):325-342.
[25]GUO Z L,ZHENG C G,SHI B C.Discrete lattice effects on the forcing term in the lattice Boltzmann method[J].Physical Review E,2002,65:046308.
[26]GUO Z L,ZHENG C G,SHI B C.An extrapolation method for boundary conditions in lattice Boltzmann method[J].Physics of Fluids,2002,14(6):2007-2010.