A retrofitting solution for geyser eruptions in storm sewer systems: experimental and numerical analysis

Geyser eruptions in storm sewer systems pose significant risks to urban infrastructure and public safety, driven by rapid air–water interactions and pressure surges. This study introduces a retrofitting system designed to mitigate geyser eruptions by enhancing air–water separation and stabilizing flow dynamics. The experimental setup, combined with numerical simulations, replicates field-scale conditions to evaluate the system's performance under varying air and water flow scenarios. Results demonstrate that the retrofitting system effectively reduces geyser heights, transitioning violent eruptions into moderate or non-eruption conditions, even under high-pressure gradients. Without retrofitting, violent eruptions occur when the air-to-water pressure head gradient (SAD) exceeds 5%. With retrofitting, eruptions remain moderate even at SAD>10%. The system achieves this by minimizing the formation of large air bubbles, controlling pressure fluctuations, and directing air to escape through designated pathways. Notably, the retrofitting system maintains its efficacy across varying conduit configurations and lengths, ensuring adaptability to diverse urban stormwater systems.