LNG重气连续点源泄漏扩散的数值模拟研究

针对LNG重气云团连续点源泄漏扩散， 结合箱模型和IIT-2模型分析了LNG云团的扩散特性。①首先，选取不同的气象条件，对扩散过程的速度、空气卷吸量、温度和高度进行数值模拟，讨论了不同大气条件下云团的流动规律、空气卷吸和气化过程等对云团扩散过程和方式的影响。数值模拟表明：一般情况下，LNG云团温度在分钟数量级达到了大气温度，进入被动扩散阶段；E级大气条件下，径向速率衰减较慢，进入被动扩散的过程非常缓慢；LNG气化过程不明显，重气效应未完全消失，不利于LNG云团的稀释和冲淡。②进而计算了下风向固定点处地面最大浓度值，并与Maplin Sands Fields Trial扩散实验的对比，验证了LNG重气扩散预测模型的可行性和合理性。③最后，分析了风速、泄放速率和大气条件对LNG扩散距离和爆炸上下限浓度扩散范围的影响。

NUMBERIC SIMULATION OF THE DISPERSION FOR CONTINUOUS RELEASE OF LNG HEAVY GAS

Aiming at the dispersion for continuous release of LNG heavy gas, combining Box Model and IIT-2 Heavy Gas Models, this paper has analyzed the character of LNG continuous release. Firstly, flow velocity, air entrainment, temperature and diffuse height in different atmospheric condition has been simulated. And the effect of flow regular, vapor process and air entrainment acted on the dispersion process and ways has been discussed. The simulation shows: general run of things, LNG vapored in several minutes and entered into passive diffusion. But in E grade of atmospheric condition, radial velocity of cloud cluster degenerated very slow and the vaporation of cloud cluster was not evident, which lead to LNG cloud cluster was with the heavy gas effect and was relatively difficult to enter into passive diffusion. All these were not beneficial to the dilution of LNG. Then, ground surface concentration in fixed point has been calculated. Compared with the Maplin Sands Fields Trial experiment, the result has proved forecast feasibility of LNG dispersion model. Finally, the effect of wind velocity, leakage rate and atmospheric condition acted on the total diffusion length and diffusion length in explosion concentration range has been discussed.