基于大涡模拟的烟塔合一烟气排放数值模拟研究  

Numerical study of flue gas diffusion for natural draft dry cooling tower with flue gas injection based on large eddy simulation

作　　者：刘志勇 丁力 朱文斌 徐振 王志刚 杨光俊 LIU Zhi-yong;DING Li;ZHU Wen-bin;XU Zhen;WANG Zhi-gang;YANG Guang-jun(Shanxi Intermational Energy Yuguang Coal and Power Co.,Ltd.,Yangquan 045100,Shanxi,China;State Power Environmental Protection Research Institute,Nanjing 210031,China)

机构地区：[1]山西国际能源裕光煤电有限责任公司,山西阳泉045100 [2]国电环境保护研究院有限公司,南京210031

出　　处：《安全与环境学报》2020年第6期2334-2343,共10页Journal of Safety and Environment

基　　金：国家自然科学基金项目(41873016);国家重大科学仪器设备开发专项(2014YQ060537)。

摘　　要：为了更准确地预测污染物的扩散和分布特性,采用计算流体力学(Computational Fluid Dynamics,CFD)方法研究自然通风干式冷却塔(Natural Draft Dry Cooling Tower,NDDCT)烟塔合一烟气扩散问题,采用大涡模拟(Large Eddy Simulation,LES)对流场和污染物质量分数场进行预测,并与非定常雷诺平均N-S(Unsteady Reynolds Average NavierStokes,URANS)进行对比,着重分析污染物质量分数脉动与速度脉动的关系。结果表明,采用LES方法模拟得到的冷却塔内壁污染物最大质量分数约为URANS结果的43倍,污染物质量分数与流场速度密切相关;2种方法得到的流场差别较大,特别是冷却塔出口和下风向位置。与URANS相比,LES可以捕捉到小尺度、高频率的流场脉动。This given paper intends to investigate the effects and the applicability of the computational fluid dynamics(short for CFD below)simulation of the pollutant emission in a natural draft dry cooling tower(NDDCT)with the flue gas injection.To make a more accurate prediction of the diffusion and distribution characteristic features of the pollutant,we have made a large eddy simulation(LES)to predict the flow field and that of the pollutant mass fraction field through a comparison with the unsteady Reynolds average Navier-Stokes(URANS)and made an emphatic analysis of the relationship between the pollutant mass fraction pulsation and the velocity fluctuation.The results of our comparative analysis show that the results of the mass flow and the thermos transfer of the cooling tower can be simulated by the URANS method,which is similar to those of LES.However,in terms of the pollutant diffusion simulation,the results of the URANS remain not yet ideal even if the unsteady algorithm is used.For instance,the maximum value of LES has been found about 43 times as that of URANS for the prediction of the pollutant mass fraction in the inner side of the cooling tower whereas the pollutant mass fraction has been closely related to the local flow field velocity.Besides,the URANS differs greatly from the LES in the flow field prediction,especially at the outlet and in the downwind direction of the cooling tower.And,what is more,in the URANS,the independent variable of the momentum equation is time average velocity,which reflects the flow field fluctuation by the turbulent kinetic energy.Hence,the turbulent kinetic energy can only be reflected in the momentum equation as an energy source moving and transformation term.And,in such a situation,even through the unsteady simulation,the URANS model can only be made to recognize some large-scale pulsating flow situations.At the same time,in the LES,the independent variable of the momentum equation can only serve as an instantaneous velocity,and,so,LES can only help to simulate and find m

关 键 词：环境工程学 自然通风干式冷却塔 烟气 污染扩散 非定常雷诺平均N-S方程 大涡模拟 

分 类 号：X511[环境科学与工程—环境工程] X513