土壤大气耦合的燃气泄漏扩散数值模拟

Numerical simulations of leakage gas dispersion based on soil and atmosphere coupling

城市燃气管网大多埋于地下,存在很多难以探测的微小泄漏,是城市公共安全的隐患。该文面向城市地下燃气管网泄漏探测和评估的需求,针对土壤和大气中燃气扩散规律的不同,在OpenFOAM中对不同的控制方程分别进行求解,并通过地面的传质通量将土壤和大气中的扩散过程进行耦合。研究泄漏量对压强和浓度分布的影响、地面对流传质系数对浓度分布和地面传质通量的影响,计算泄漏燃气在城市街道峡谷中的分布情况。结果表明:地面传质通量分布对街道峡谷中的甲烷浓度分布影响很小,为埋地燃气管道泄漏的探测和评估提供了参考和依据。

Most urban gas pipelines are buried underground. Small leaks can occur and are difficult to detect, which is a threat to urban public safety. Thus, gas leaks in buried gas lines need to be detected and assessed. The leaks can be located by analyzing the coupled gas dispersion in the soil and atmosphere. Different governing equations were used to model the dispersion in the soil and atmosphere in OpenFOAM. The flows were coupled through the mass flux leaving the ground surface. The models were used to investigate the impact of the leakage rate on the pressure and concentration distribution and the impact of the convective mass transfer coefficient on the concentration distribution and ground mass flux. The gas distribution in an urban street canyon was analyzed to show that the ground mass flux has little effect on the methane distribution in the street canyon. The model can be used as a reference for leak detection and assessments of buried gas pipelines.