In urban stormwater systems, a rapid increase in water inflow can cause the entrapment of air pockets and subsequent ejection of air/water mixture, commonly known as storm geysers. In this study, a three-dimensional computational fluid dynamics model was built based on a lab model, which consisted of an upstream pipe and a downstream pipe with different invert elevation (i.e. a drop), connected by a chamber with a riser on the top. The effects of the downstream pipe characteristics, location of the entrapped air pocket, and its volume on the pressure variation were examined. With the downstream pipe flowing in full, two mechanisms that possibly trigger geyser events were simulated and experimentally validated: (1) a rapid inflow front in the upstream pipe with the flow changing from free surface flow to pressurized flow, and (2) the air pocket releasing in a pressurized system. For the first mechanism, the pressure surge in the chamber was related to the capacity of the downstream pipe for the increased flow rate. For the second mechanism, a smaller air pocket in the upstream pipe can generate a higher pressure during the geyser event due to the reduced damping effect on the pressure variation. A larger pressure drop was observed for a larger volume of released air. Lower peak pressure was generated for an air pocket closer to the chamber due to the shorter duration for pressure to build up before the air pocket reached the chamber.

在城市雨水系统中，进水量的快速增加会导致气穴的滞留和随后的空气/水混合物喷出，通常称为风暴间歇泉。本研究基于实验室模型建立了三维计算流体动力学模型，该模型由一个上游管道和一个下游管道组成，具有不同的倒置高度（即落差），由顶部带有立管的腔室连接。 . 检查了下游管道特性、截留气穴的位置及其体积对压力变化的影响。随着下游管道完全流动，模拟和实验验证了两种可能触发间歇泉事件的机制：（1）上游管道中的快速流入前沿，流动从自由表面流动变为加压流动，(2) 在加压系统中释放气穴。对于第一种机制，腔室中的压力波动与下游管道增加流量的能力有关。对于第二种机制，由于减少了对压力变化的阻尼效应，上游管道中较小的气穴可以在间歇泉事件期间产生更高的压力。对于较大体积的释放空气，观察到较大的压降。由于在气穴到达腔室之前建立压力的持续时间较短，因此靠近腔室的气穴产生了较低的峰值压力。由于减少了对压力变化的阻尼效应，上游管道中较小的气穴可以在间歇泉事件期间产生更高的压力。对于较大体积的释放空气，观察到较大的压降。由于在气穴到达腔室之前建立压力的持续时间较短，因此靠近腔室的气穴产生了较低的峰值压力。由于减少了对压力变化的阻尼效应，上游管道中较小的气穴可以在间歇泉事件期间产生更高的压力。对于较大体积的释放空气，观察到较大的压降。由于在气穴到达腔室之前建立压力的持续时间较短，因此靠近腔室的气穴产生了较低的峰值压力。