In order to study the diffusion behavior of gas in the atmosphere under the unsteady leakage condition of buried gas pipeline,the CFD was applied to solve the diffusion equations of soil and atmosphere respectively based on the unsteady leak-age big-hole model of gas pipeline. The numerical simulation of leakage and diffusion was carried out by coupling the soil and atmosphere environment with the ground diffusion flux of propane,and the calculation results were compared with the numeri-cal simulation results of the above-ground leakage and diffusion. It showed that under the conditions of coupling simulation, the wind speed was still the main factor influencing the diffusion distance and height of propane,and the influence of temper-ature and relative humidity on the diffusion of propane were relatively small. Compared with the buried leakage,both the dif-fusion distance and height of above-ground leakage under different conditions had the error, in which the error of diffusion distance were generally larger,while the error of diffusion height were larger in some individual cases. The simulation results under the condition of above-ground leakage were relatively larger,which would cause significant influence on the accuracy of accident prediction and assessment.%为了研究埋地燃气管道泄漏燃气在非稳态泄漏条件下的扩散行为,基于燃气管道非稳态泄漏大孔模型,应用CFD分别求解土壤和大气扩散方程,通过丙烷地面扩散通量耦合了土壤和大气环境,进行了泄漏扩散的数值模拟,所得模拟计算结果与地上泄漏扩散数值模拟结果进行了对比分析.研究结果表明:耦合模拟条件下,风速仍是影响丙烷扩散距离和高度的主要因素;温度和相对湿度对丙烷扩散有相对较小的影响;与埋地泄漏相比,不同条件下地上泄漏的扩散距离和扩散高度均有误差,水平扩散距离误差普遍较大,扩散高度个别情况下误差较大;地上泄漏条件下的模拟结果数值偏大,对事故的预测和评估准确性会产生显著影响.
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