Abstract：
Ventilation is paramount in sanitary and stormwater sewer systems to mitigate odor problems and avert pressure surges. Existing numerical models have constraints in practical applications in actual sewer systems due to insufficient airflow modeling or suitability only for steady-state conditions. This research endeavors to formulate a mathematical model capable of accurately simulating various operational conditions of sewer systems under the natural ventilation condition. The dynamic water flow is modeled using a shock-capturing MacCormack scheme. The dynamic airflow model amalgamates energy and momentum equations, circumventing laborious pressure iteration computations. This model utilizes friction coefficients at interfaces to enhance the description of the momentum exchange in the airflow and provide a logical explanation for air pressure. A systematic analysis indicates that this model can be easily adapted to include complex boundary conditions, facilitating its use for modeling airflow in real sewer networks. Furthermore, this research uncovers a direct correlation between the air-to-water flow rate ratio and the filling ratio under natural ventilation conditions, and an empirical formula encapsulating this relationship is derived. This finding offers insights for practical engineering applications.
摘要：
在卫生和雨水下水道系统中，通风对于减轻气味问题和避免压力波动至关重要。由于气流建模不足或仅适用于稳态条件，现有的数值模型在实际下水道系统中的实际应用中受到限制。这项研究努力制定一个数学模型，能够准确地模拟自然通风条件下下水道系统的各种运行条件。使用冲击捕获MacCormack方案对动态水流进行建模。动态气流模型融合了能量和动量方程，规避费力的压力迭代计算。该模型利用界面处的摩擦系数来增强对气流中动量交换的描述，并为气压提供逻辑解释。系统分析表明，该模型可以很容易地适应复杂的边界条件，便于将其用于真实下水道网络中的气流建模。此外，这项研究揭示了在自然通风条件下，空气与水流量比与填充比之间的直接相关性，并推导出了包含这种关系的经验公式。这一发现为实际工程应用提供了见解。
