Abstract: Disturbances of cooling towers on wind and turbulence field were simulated with a computational fluid dynamics model, Fluent. The influence on atmospheric dispersion was simulated by using a Lagrangian stochastic particle model. With 4 cooling towers and 4 emission stacks, and a typical wind speed of 1.5 m/s at a nuclear power station site, flow disturbances under neutral condition were simulated for three wind directions, i.e., ESE, SSE and SW. Dispersion plumes and their standard deviations were calculated for each wind direction and 2 selected stacks. Results show that, in case of wind direction with least disturbance on the air flow, there can be almost no influence of the cooling tower at the dispersion. While with significant influence of the air flow disturbance, the standard deviations of plumes can be increased for 2 and 1 stability classes in horizontal and vertical direction. The influence is mostly significant within 1 km of downwind distance.

Key words: atmospheric dispersion, cooling tower, numerical simulation, Fluent model, stochastic particle model

摘要： 利用计算流体力学模型Fluent, 模拟多个冷却塔对大气流动和湍流场的作用, 用拉格朗日随机粒子模式进一步模拟其大气扩散影响。针对一个内陆核电厂的设计方案进行模拟, 共有4个冷却塔和4个常规烟囱排放口。取当地典型风速1.5 m/s和中性边界层条件模拟ESE, SSE和SW这3个方向来流的塔体扰动情况。对应各风向各取2个排放位置进行扩散模拟并计算扩散参数。结果显示, 在扰动最小的风向条件下, 冷却塔几乎对扩散没有影响, 扰动严重时水平和垂直扩散参数可分别增大2个和1个稳定度级别, 这种影响在1 km之内最为明显。

关键词: 大气扩散, 冷却塔, 数值模拟, Fluent软件, 随机粒子模式