Experiments of combinational fans affecting smoke ceiling in an undersea metro interval tunnel VSES

Abstract Based on a case study of the undersea metro interval tunnel, this study proposes a model to evaluate the Ventilation and Smoke Exhaust System (VSES). In the VSES experiments, data of fan frequencies, powers, velocities, and static pressures in carriageways are collected, under the TPTE (Two Pressing-in fans + Two Extracted-out fans), the TPOEL (Two Pressing-in fans + One Extraction fan on the Left side of a smoke ceiling vent) and the TPOER (Two Pressing-in fans + One Extraction fan on the Right side of a smoke ceiling vent) combinations. The results show that the static pressures in both carriageways have fluctuation phenomena and symmetrical distributions, whose axis of symmetry is the smoke ceiling, regardless of combination type. These fluctuations have almost constant static pressures, which are associated with the increase in consumed powers while hardly compensate for the increase in volume flow rates. These rare compensations are essential to evaluate the effects of combinations on the relative shock loss. In order to quantify the differences, this study proposes a VSES performance and a deviation percentage model, and the results show that the TPTE resistance has the smallest shock losses of airflow going through the smoke ceiling vent.