This study focused on increasing the efficiency of the smoke exhaust system of an extra-wide(eight-lane,dual-directional)immersed tunnel with a specific quantity of exhaust.The Shenzhen-Zhongshan immersed tunnel was s...This study focused on increasing the efficiency of the smoke exhaust system of an extra-wide(eight-lane,dual-directional)immersed tunnel with a specific quantity of exhaust.The Shenzhen-Zhongshan immersed tunnel was selected as the application example.A numerical simulation based on fire dynamics simulator was conducted.In the model,the concrete structure of the main body of the immersed tubes was not altered.The adoption of supplementary exhaust ducts increased the efficiency from 73%to 98%under the condition of no longitudinal wind.When a 50-MW fire occurred between two adjacent ducts,with a longitudinal wind velocity of 2 m/s,the efficiency reached 88%or more when the two ducts were opened.Furthermore,a safety evacuation path was developed.The results suggest that the addition of supplementary exhaust ducts combined with a rational longitudinal wind velocity is necessary for an extra-wide immersed tunnel.展开更多
In case of an emergency fire in vehicle tunnel, the ventilation system should be operated effectively to control the thermal fume and smoke inside tunnel. However, it is quite difficult to predict every kind of emerge...In case of an emergency fire in vehicle tunnel, the ventilation system should be operated effectively to control the thermal fume and smoke inside tunnel. However, it is quite difficult to predict every kind of emergency fire by fire tests because the actual movement of thermal fume and smoke is affected by many factors such as ventilation system, structure of the tunnel, etc., especially for tunnels equipped with transverse ventilation system on which rare experimental and numerical studies have been found so far. In this paper, a three dimensional numerical simulator using LES turbulence model is developed to simulate the movement of thermal fume induced by emergency fire in vehicle tunnel. The SMAC method is employed to calculate the pressure and velocity fields. The upwind differnece scheme with the third order accuracy is applied for the discretization of convection terms of the governmental equations. As the applications of the present simulator, the behavior of thermal fume induced by emergency fire in a vehicle tunnel with two direction traffic is analyzed. It is confirmed that the partial transverse ventilation system is more effective than the longitudinal ventilation system under large and small velocities of longitudinal bulk flow inside tunnel. Simulation result also shows that remaining the velocity of longitudinal bulk flow near zero around fire source can provide the best working condition for partial transverse ventilation system.展开更多
基金Project supported by the National Key R&D Program of China(No.2018YFC0808103)。
文摘This study focused on increasing the efficiency of the smoke exhaust system of an extra-wide(eight-lane,dual-directional)immersed tunnel with a specific quantity of exhaust.The Shenzhen-Zhongshan immersed tunnel was selected as the application example.A numerical simulation based on fire dynamics simulator was conducted.In the model,the concrete structure of the main body of the immersed tubes was not altered.The adoption of supplementary exhaust ducts increased the efficiency from 73%to 98%under the condition of no longitudinal wind.When a 50-MW fire occurred between two adjacent ducts,with a longitudinal wind velocity of 2 m/s,the efficiency reached 88%or more when the two ducts were opened.Furthermore,a safety evacuation path was developed.The results suggest that the addition of supplementary exhaust ducts combined with a rational longitudinal wind velocity is necessary for an extra-wide immersed tunnel.
文摘In case of an emergency fire in vehicle tunnel, the ventilation system should be operated effectively to control the thermal fume and smoke inside tunnel. However, it is quite difficult to predict every kind of emergency fire by fire tests because the actual movement of thermal fume and smoke is affected by many factors such as ventilation system, structure of the tunnel, etc., especially for tunnels equipped with transverse ventilation system on which rare experimental and numerical studies have been found so far. In this paper, a three dimensional numerical simulator using LES turbulence model is developed to simulate the movement of thermal fume induced by emergency fire in vehicle tunnel. The SMAC method is employed to calculate the pressure and velocity fields. The upwind differnece scheme with the third order accuracy is applied for the discretization of convection terms of the governmental equations. As the applications of the present simulator, the behavior of thermal fume induced by emergency fire in a vehicle tunnel with two direction traffic is analyzed. It is confirmed that the partial transverse ventilation system is more effective than the longitudinal ventilation system under large and small velocities of longitudinal bulk flow inside tunnel. Simulation result also shows that remaining the velocity of longitudinal bulk flow near zero around fire source can provide the best working condition for partial transverse ventilation system.
