基于实验与仿真的三维水下气体泄漏预测与安全评估研究

水下气体羽流特性是海底气体泄漏风险评估的重要基础。为准确预测水下气体羽流行为，基于计算流体动力学(CFD)方法，建立1种考虑气体卷吸湍流特性的三维水下气体羽流数值预测模型；采用欧拉-欧拉流体体积模型捕捉气液作用界面，以大涡模拟(LES)方式预测羽流上浮及卷吸过程中的湍流特性，从而实现对水下气体羽流行为的预测；搭建小尺度实验平台，对比仿真与实验条件下的气体羽流形态，验证数值模型的可行性及预测精度；应用建立的数值模型对工程条件下的水下气体泄漏事故进行预测和评估，以某浅层气井喷事故为例，评估水下气体羽流上浮时间、海面影响范围和涌流高度。结果表明:基于欧拉多相流与大涡模拟的数值模型对水下气体羽流预测结果与实验具有较好的吻合度，该模型能够较好捕捉羽流的湍流特性，可为水下气体泄漏羽流行为评估提供参考。

Study on three dimensional prediction and safety assessment of underwater gas leakage based on experiment and simulation

The underwater gas plume characteristics are the important basis of risk assessment on submarine gas leakage.To accurately predict the underwater gas plume behavior,a three dimensional numerical prediction model of underwater gas plume considering the gas entrainment turbulence characteristics was established based on the computational fluid dynamics (CFD) method.The gas liquid effect interface was caught by using the Eulerian Eulerian fluid volume model,and the turbulence characteristics during the plume rising and entrainment processes were predicted by the large eddy simulation (LES) approach,so as to realize the prediction on the underwater gas plume behavior.A small scale experimental platform was established to compare the gas plume patterns under the simulation and experiment conditions,then the feasibility and prediction precision of numerical model were verified.The established numerical model was applied to predict and assess the underwater gas leakage accident under the engineering conditions,and the rising time,sea surface influence range and fountain height of underwater gas plume were assessed by taking a shallow gas well blowout accident as an example.The results showed that the prediction results of underwater gas plume by the numerical model based on the Eulerian multi phase flow and LES agreed well with the experimental results.The numerical model is capable of catching the turbulence characteristics of plume well,which can provide reference for the assessment of underwater gas leakage plume behavior.