Influence of Smoke Exhaust Volume and Smoke Vent Layout on the Ceiling Centralized Smoke Exhaust Effect in Tunnel Fires

Abstract

This research focuses on the impact of smoke exhaust volume and smoke vent layout, which are two crucial factors affecting the smoke control efficiency in tunnels, on the smoke exhaust effect in tunnel fires. Numerical simulation methods are employed to investigate the impact of changing the smoke exhaust volume and the smoke vent number on the smoke exhaust performance in a curved tunnel with a ceiling centralized smoke exhaust system. This research primarily examines the length of the smoke distribution, the smoke temperature under the ceiling, the vertical visibility, and the exhausted smoke mass flow rate. The findings indicate that, in a tunnel with a single-side ceiling centralized smoke exhaust mode, an imbalance in smoke distribution occurs between the upstream and downstream of the fire source. The upstream area experiences a higher amount of smoke, while the downstream area has thinner smoke. Increasing the smoke exhaust volume yielded positive effects on smoke control, as evident in the reduced the smoke spread range, and improved the smoke exhaust efficiency. The influence of changing smoke vent number on the smoke exhaust effect was dependent on the smoke exhaust volume. When the smoke exhaust volume was excessive, altering the number of smoke vents had a minimal impact on smoke exhaust, while in cases with small smoke exhaust volumes, changes in smoke vent numbers obviously influenced the smoke control effect. Therefore, selecting an appropriate smoke exhaust volume and raising the smoke vent number can effectively optimize the performance of the ceiling centralized smoke exhaust system.