Experimental Study on Smoke Exhaust Performance of Multi-fan Combination in Subsea Tunnel

In order to realize the efficient smoke exhaust of tunnel ventilation system with multi-fan combination, a 1 :10 scale test model was established. Its engineering prototype is the Wagui section tunnel of Metro Line 1, which runs under Qingdao Jiaozhou Bay. Based on the experiment model, the fan power consumption, wind velocity and static pressure in the carriageway are measured to quantify the impact of four fan combinations and their operating parameters on the flow field parameters in the tunnel. The research shows that there is airflow stagnation in the area around the smoke outlet. The airflow stagnation is the external representation of the balance relationship between the inertial force and the pressure difference force. In order to measure the airflow stagnation effect, the Eu expression is derived using the dimensionless criterion. Using this expression, the smoke exhaust performance of four fan combinations is compared. The results show that the smoke exhaust performance of the four fans combination is the best, the three fans combination are the second, and the smoke exhaust performance of the two fans combination is the worst. This shows that opening the exhaust fan can significantly improve the ventilation and smoke exhaust capacity of the system.