坡屋面建筑周围放射性物质扩散的数值模拟
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摘要
坡屋面建筑分布广泛,周围风场分布复杂,为解决放射性物质的绕流扩散问题,运用Open FOAM对坡屋面建筑周围的不可压缩稳态流场进行了三维数值模拟,增加组分扩散方程,研究了入流风速和屋顶倾角对放射性物质扩散的影响。结果表明,入流风速越大,放射性物质扩散越充分。坡屋面建筑排布影响风场分布,进而影响烟羽形状。当上游建筑的屋顶倾角在15°左右、下游建筑的屋顶倾角在25°左右时,在竖直截面上,速度流线沿下游建筑背风坡面爬升,烟羽抬升较高,烟羽呈上扬型;在水平截面上,顺时针涡旋和逆时针涡旋对称分布,导致烟羽对称分布,此时污染范围最小,扩散作用最为显著。可见合理的建筑布局可以减小放射性污染事件对周围环境造成的危害。
To prevent the radioactive material from diffusing to the surrounding slope-roof buildings,this paper has done a 3-D numerical simulation by using an open source software named Open FOAM,intended usually for the computational fluid dynamics( CFD) based on the SIMPLE algorithm. For the said purpose,it is necessary to take into account the effect of the emission rate on the concentration of the radioactive material and the pollutant convection diffusion equation. In addition, we have also made an exploration of the influence of the flow-in wind velocity and the sloping degree of the building roof on the radioactive material. The results of our simulation show that,with the increase of the inflow wind velocity,the diffusion of radioactive material would be enhanced,too. What is more,the wind direction across the building canyons is also likely to affect the concentration distribution near the wall in the vertical section. Besides,if the wind comes parallel to the wall,it would also be smooth for the radioactive material to be brought out of the canyon. On the other hand,the building layout itself can also affect the smoke plume shape. For example,suppose the roof inclination of the upstream building tends to be about 15° whereas the downstream building were to be about 25°,it would be easy for the wind to blow up in a streamlining direction along the leeward slope of the downstream building. And,accordingly,the smoke plume would be brought up high with the plume ascending,thus,the radioactive material can be diffused more sufficiently. As to the horizontal section,the vortex on the leeward side of the downstream building is related to its layout. If the roof slopes of the upstream and downstream buildings are the same( both 25° or both 15°),the main vortex would be clockwise. But,when the roof slope of the upstream building is greater than that of the downstream one( α1= 25°,α2= 15°),the main vortex would be in turn counterclockwise. Moreover,if the roof inclination of the upstream building is less than that of the downstream one( α1= 15°,α2= 25°),it would be possible for the clockwise vortex and that of counterclockwise to be distributed symmetrically,which helps to result in the symmetry of the plume,so that the range of pollution can be made to the minimum degree.
To prevent the radioactive material from diffusing to the surrounding slope-roof buildings,this paper has done a 3-D numerical simulation by using an open source software named Open FOAM,intended usually for the computational fluid dynamics( CFD) based on the SIMPLE algorithm. For the said purpose,it is necessary to take into account the effect of the emission rate on the concentration of the radioactive material and the pollutant convection diffusion equation. In addition, we have also made an exploration of the influence of the flow-in wind velocity and the sloping degree of the building roof on the radioactive material. The results of our simulation show that,with the increase of the inflow wind velocity,the diffusion of radioactive material would be enhanced,too. What is more,the wind direction across the building canyons is also likely to affect the concentration distribution near the wall in the vertical section. Besides,if the wind comes parallel to the wall,it would also be smooth for the radioactive material to be brought out of the canyon. On the other hand,the building layout itself can also affect the smoke plume shape. For example,suppose the roof inclination of the upstream building tends to be about 15° whereas the downstream building were to be about 25°,it would be easy for the wind to blow up in a streamlining direction along the leeward slope of the downstream building. And,accordingly,the smoke plume would be brought up high with the plume ascending,thus,the radioactive material can be diffused more sufficiently. As to the horizontal section,the vortex on the leeward side of the downstream building is related to its layout. If the roof slopes of the upstream and downstream buildings are the same( both 25° or both 15°),the main vortex would be clockwise. But,when the roof slope of the upstream building is greater than that of the downstream one( α1= 25°,α2= 15°),the main vortex would be in turn counterclockwise. Moreover,if the roof inclination of the upstream building is less than that of the downstream one( α1= 15°,α2= 25°),it would be possible for the clockwise vortex and that of counterclockwise to be distributed symmetrically,which helps to result in the symmetry of the plume,so that the range of pollution can be made to the minimum degree.
引文
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[12]TANG Xiuhuan(唐秀欢),YANG Ning(杨宁),BAO Lihong(包利红),et al.CFD simulation of the radioactive gas dispersion in Xi'an pulsed reactor site environment[J].Journal of Safety and Environment(安全与环境学报),2014,14(5):133-140.
[13]DUAN Zhongshan(段中山),YUAN Tao(袁涛),FENG Xiaojie(冯孝杰),et al.Simulation study on diffusion of smoke cluster from dirty bomb explosion in subway station[J].Radiation Protection(辐射防护),2016,36(5):279-284.
[14]YUE Di(乐地),LI Nianping(李念平),SU Lin(苏林),et al.Numerical simulation of wind environment in the urban areas[J].Journal of Safety and Environment(安全与环境学报),2012,12(3):259-264.
[15]HANNA S R,HANSEN O R,ICHARD M,et al.CFD model simulation of dispersion from chlorine railcar releases in industrial and urban areas[J].Atmospheric Environment,2009,43(2):262-270.
[16]MAZZOLDI A,HILL T,COLLS J J.CFD and Gaussian atmospheric dispersion models:a comparison for leak from carbon dioxide transportation and storage facilities[J].Atmospheric Environment,2008,42(34):8046-8054.
[17]ZHENG T,NI S,SHEN S,et al.Numerical study of radioactive pollutants dispersion in radioactive“dirty bomb”events[C]//Proceedings of the International Conference on Information Systems for Crisis Response and Management,Rio de Janeiro,Brasil:ISCRAM Association,2016.
[18]CHEN Jianguo(陈建国),PAN Siming(潘思铭),LIU Yi(刘奕,)et al.Numerical prediction and transportation study of poisonous gas transport on complex terrain[J].Journal of Tsinghua University:Science and Technology(清华大学学报:自然科学版),2007,47(3):381-384.
[19]KOUTSOURAKIS N,BARTZIS J G,MARKATOS N C.Evaluation of reynolds stress,κ-ε,and RNGκ-ε,turbulence models in street canyon flows using various experimental data sets[J].Environmental Fluid Mechanics,2012,12(4):379-403.
[20]DALY B J,HARLOW F H.Transport equations in turbulence[J].Physics of Fluids,1970,13(13):2634-2649.
[21]SABATINO S D,BUCCOLIERI R,PULVIRENTI B,et al.Flow and pollutant dispersion in street canyons using FLUENT and ADMS-Urban[J].Environmental Modeling&Assessment,2008,13(3):369-381.
[22]WANG Y,HUANG H,HUANG L.Numerical study of leaked natural gas dispersion within an urban street canyon considering the distribution of ground surface flux[C]//Proceedings of the International Conference on Civil Engineering and Urban Planning,Beijing:CEUP Association,2015.
[23]YANG Rui(杨锐),ZHANG Jing(张婧),SHEN Shifei(申世飞),et al.Numerical investigation of the impact of different configurations and aspect ratios on dense gas dispersion in urban street canyons[J].Journal of Tsinghua University:Science and Technology(清华大学学报:自然科学版),2007,12(3):345-351.
[24]HUANG Yuandong(黄远东),JIN Xin(金鑫),JIN Mingxia(金铭霞),et al.Influence of turbulence models and Schmidt number on numerical simulation of pollutant dispersion in a street canyon[J].Journal of University of Shanghai(上海理工大学学报),2009,31(2):133-138.
[25]BAIK J J,KIM J J.A numerical study of flow and pollutant dispersion characteristics in urban street canyons[J].Journal of Applied Meteorology,1999,38(11):1576-1589.
[2]SUN Zhikuan(孙志宽).Study on Gauss plume diffusion model again[J].Environment and Sustainable Development(环境与可持续发展),2013,38(5):107-109.
[3]STOCKIE J M.The mathematics of atmospheric dispersion modeling[J].Siam Review,2011,53(2):349-372.
[4]PASQUILL F.The estimation of the dispersion of windborne material[J].Australian Meteorological Magazine,1961,90:33-49.
[5]CLARK M J,SMITH F B.Wet and dry deposition of chernobyl releases[J].Nature,1988,332(6161):245-249.
[6]HUH C A,HSU S C,LIN C Y.Fukushima-derived fission nuclides monitored around Taiwan:Free tropospheric versus boundary layer transport[J].Earth and Planetary Science Letters,2012,319/320:9-14.
[7]KORSAKISSOK I,MATHIEU A,DIDIER D.Atmospheric dispersion and ground deposition induced by the fukushima nuclear power plant accident:a local-scale simulation and sensitivity study[J].Atmospheric Environment,2013,70(4):267-279.
[8]YU M,OHARA T,NISHIZAWA M.Atmospheric behavior,deposition,and budget of radioactive materials from the Fukushima Daiichi Nuclear Power Plant in March 2011[J].Geophysical Research Letters,2011,38(7):136-147.
[9]SRINIVAS C V,VENKATESAN R,BAKARAN R,et al.Regional scale atmospheric dispersion simulation of accidental releases of radionuclides from Fukushima Dai-ichi reactor[J].Atmospheric Environment,2012,61(12):66-84.
[10]MIAO Yucong(缪育聪),LIU Shuhua(刘树华),CHEN Bicheng(陈笔澄),et al.Simulating urban flow and dispersion in Beijing by coupling a CFD Model with the WRF Model[J].Advances in Atmospheric Sciences(大气科学进展),2013,30(6):1663-1678.
[11]HU Xiaofeng(胡啸峰),HUANG Hong(黄弘),SHEN Shifei(申世飞).Simulations of atmospheric dispersion of radioactive materials with the urban canopy model[J].Journal of Tsinghua University:Science and Technology(清华大学学报:自然科学版),2014,54(6):711-718.
[12]TANG Xiuhuan(唐秀欢),YANG Ning(杨宁),BAO Lihong(包利红),et al.CFD simulation of the radioactive gas dispersion in Xi'an pulsed reactor site environment[J].Journal of Safety and Environment(安全与环境学报),2014,14(5):133-140.
[13]DUAN Zhongshan(段中山),YUAN Tao(袁涛),FENG Xiaojie(冯孝杰),et al.Simulation study on diffusion of smoke cluster from dirty bomb explosion in subway station[J].Radiation Protection(辐射防护),2016,36(5):279-284.
[14]YUE Di(乐地),LI Nianping(李念平),SU Lin(苏林),et al.Numerical simulation of wind environment in the urban areas[J].Journal of Safety and Environment(安全与环境学报),2012,12(3):259-264.
[15]HANNA S R,HANSEN O R,ICHARD M,et al.CFD model simulation of dispersion from chlorine railcar releases in industrial and urban areas[J].Atmospheric Environment,2009,43(2):262-270.
[16]MAZZOLDI A,HILL T,COLLS J J.CFD and Gaussian atmospheric dispersion models:a comparison for leak from carbon dioxide transportation and storage facilities[J].Atmospheric Environment,2008,42(34):8046-8054.
[17]ZHENG T,NI S,SHEN S,et al.Numerical study of radioactive pollutants dispersion in radioactive“dirty bomb”events[C]//Proceedings of the International Conference on Information Systems for Crisis Response and Management,Rio de Janeiro,Brasil:ISCRAM Association,2016.
[18]CHEN Jianguo(陈建国),PAN Siming(潘思铭),LIU Yi(刘奕,)et al.Numerical prediction and transportation study of poisonous gas transport on complex terrain[J].Journal of Tsinghua University:Science and Technology(清华大学学报:自然科学版),2007,47(3):381-384.
[19]KOUTSOURAKIS N,BARTZIS J G,MARKATOS N C.Evaluation of reynolds stress,κ-ε,and RNGκ-ε,turbulence models in street canyon flows using various experimental data sets[J].Environmental Fluid Mechanics,2012,12(4):379-403.
[20]DALY B J,HARLOW F H.Transport equations in turbulence[J].Physics of Fluids,1970,13(13):2634-2649.
[21]SABATINO S D,BUCCOLIERI R,PULVIRENTI B,et al.Flow and pollutant dispersion in street canyons using FLUENT and ADMS-Urban[J].Environmental Modeling&Assessment,2008,13(3):369-381.
[22]WANG Y,HUANG H,HUANG L.Numerical study of leaked natural gas dispersion within an urban street canyon considering the distribution of ground surface flux[C]//Proceedings of the International Conference on Civil Engineering and Urban Planning,Beijing:CEUP Association,2015.
[23]YANG Rui(杨锐),ZHANG Jing(张婧),SHEN Shifei(申世飞),et al.Numerical investigation of the impact of different configurations and aspect ratios on dense gas dispersion in urban street canyons[J].Journal of Tsinghua University:Science and Technology(清华大学学报:自然科学版),2007,12(3):345-351.
[24]HUANG Yuandong(黄远东),JIN Xin(金鑫),JIN Mingxia(金铭霞),et al.Influence of turbulence models and Schmidt number on numerical simulation of pollutant dispersion in a street canyon[J].Journal of University of Shanghai(上海理工大学学报),2009,31(2):133-138.
[25]BAIK J J,KIM J J.A numerical study of flow and pollutant dispersion characteristics in urban street canyons[J].Journal of Applied Meteorology,1999,38(11):1576-1589.