锥形水幕稀释丙烷泄漏扩散的数值模拟研究

Numerical simulation of the water curtain Mitigating propane dispersion

采用CFD软件Fluent对有无水幕作用情况下丙烷泄漏扩散过程进行了数值模拟,探讨了上喷锥形水幕对丙烷扩散的影响,得到了不同情况下丙烷体积分数场、速度场分布,并在此基础上讨论了锥形水幕稀释丙烷泄漏扩散的机理。结果表明:无水幕情况下气体扩散稳定无湍流;水幕开启初期会形成较强的上升气流,随后在水幕周围较大范围造成逆时针流场,当水幕成型后,逆时针流场开始偏转,最终形成复杂的湍流流场;一部分丙烷被上升气流带到水幕上方与空气混合,另一部分丙烷穿过水幕或在湍流扰动下绕到水幕后方与后方空气混合稀释后向出口处扩散;开启水幕后,地面处丙烷体积分数下降非常明显,高处丙烷体积分数略有增加。分析得出锥形水幕稀释丙烷气云扩散机理:上喷锥形水幕在水幕附近形成较强湍流,加快空气流通速率,吸卷更多的空气到水幕处,与水幕处泄漏气体混合,同时湍流加强了周围流场流通速率,防止气体积聚,从而达到稀释气体的目的。

In this paper, natural dispersion and force dispersion of propane with water curtain were simulated by computational fluid dynamic（CFD） method. The impact of upward cone water curtain on propane dispersion was discussed. The distributions of concentration and velocity field were obtained through simulation data. On that basis, the diffusion mechanism of diluting propane dispersion with the upward cone water certain was discussed. A conclusion can be drawn that gas spread steady without turbulence in natural dispersion. At initial time when water curtain was opened, a strong upflow which cut the gascloud into two segments turned up, and then a counterclockwise flow field appeared in a large area around curtain. Direction of motion of propane started to change to inverse hour under the influence of the courterclockwise flow field. As soon as the water curtain took shape, the counterclockwise flow field changed direction, and a complex flow field formed finally. Beneath the complex turbulent, a part of propane was pushed up to mix with air aloft while another part passed through the curtain. The rest moved round the curtain to mix with air behind the water curtain. Then the mixed gas which was diluted by water curtain dispersed to exit. According to the charts ploted by the simulation data, the concentration of propane decreased significantly on ground after the water curtain was opened, while there was a little increase overhead. Based on the simulation, diffusion mechanism of diluting propane dispersion with the upward cone water certain was put forward： upward conical water curtain causes strong turbulent which speeds up the air circulation rate and induces more air inside the spray to mix with escaped gas. Mixing between the gas and air is enhanced. At the same time, turbulent intensifies flow rate to prevent gas from accumulating and achieve the goal of diluting gas.