重气云团瞬时泄漏扩散的数值模拟研究

事故性泄漏多形成重气云团 ,其扩散行为与非重气云团有很大的不同 ,主要包括重力沉降、空气卷吸、云团加热和向非重气云团转变四个阶段。文中从控制重气云团扩散行为的微分方程入手 ,根据箱模型(boxmodel)及其他一些重气扩散模型 ,如IITHeavyGasModels模型和虚点源模型 ,采用向前插分和牛顿迭代的方法 ,针对ThorneyIslandTrialNo .0 0 8试验进行了数值模拟 ,得到了重气云团外形尺寸 (云团半径和云团高度 )和空气卷吸量随时间的变化关系以及下风向固定点处地面最大浓度值。数值模拟结果较好地反映了重气云团所特有的扩散行为。针对数值模拟结果与试验实测值之间存在的偏差进行了分析 ,结果表明 ,采用该方法进行重气云团瞬时泄漏扩散模拟是可行的 ,且模拟精确度高于IITHeavyGasModels模型

Numerical Simulation Research on Instantaneous Release Dispersion of Heavy Gases

In some release accidents, dense gases are formed, and its dispersion behaviour is more different from passive dispersion. Heavy gas dispersion mainly includes gravitational slumping, entrainment of air, cloud cluster heating and transition to the passive phase. The forward finite difference and Newton iterance are used in the light of box model and other heavy gas dispersion models, such as IIT Heavy Gas Models and virtual point source model, to solve the differential equations of controlling heavy gas cloud dispersion behaviour in order to simulate the Thorney Island Trial 008 to obtain the relationship between the shape character (cloud cluster radius and cloud cluster height) and the time after release, the relationship between air entrainment quality and the time after release and predict maximum mole component at various downwind distance on the ground level from the release point. The simulation results well reflect the special dispersion behaviour of heavy gas cloud. Analysis are made to interpret the difference between simulation results and experimental data, and the results indicate that the method which is used to simulate the dispersion behavior of heavy gas cloud is feasible and the precision is higher than that of IIT Heavy Gas Models.