Numerical studies on evaluation of smoke control system of underground metro rail transport system in India having jet injection system: A case study

Abstract

The rail based urban transport system is being developed for national capital of India, New Delhi. The smoke control using ventilation in case of fire inside the tunnel, similar to Delhi Metro corridor has been investigated using computational fluid dynamics technique. A section of tunnel having dimensions 400 m long, 5.5 m wide and 6 m high is considered for simulation. The analysis has been carried out by assuming a variable fire source with a peak heat release rate (HRR) of 16 MW, located at the center of the tunnel. Ventilation ducts are located in the ceiling near the tunnel portals and are inclined at 10 degrees to the plane of the ceiling through which fans discharge air. The influence of the fire HRR curve slope on the smoke flow dynamics in a realistic tunnel model fitted with jet injection type longitudinal ventilation system has been investigated. In case of fire two cases are studied: (1) fans activated immediately after detection, (2) fans activated at delayed times to take into account the response time for the fans to achieve its maximum speed. The velocity of supply and exhaust fans necessary to remove smoke in 30 s from the upstream direction is determined. The velocities of fan required to produce desired critical velocity in the longitudinal direction for different HRR of fire is predicted. Keywordstunnel fires, computational fluid dynamics, ventilation, inclined ducts Article History

Optimisation Analysis of Structural Parameters of an Annular Slot Ejector Based on the Coanda Effect

“…eir work showed that when the pressure increases, the potential splash zone tends to move downstream. In recent years, the introduction of the Coanda effect has promoted research into, and development of, annular ejectors [10,[16][17][18][19][20][21][22][23][24][25].…”

“…Jain et al developed a new ejector model with two nozzles to investigate the relationship between the structural parameters (nozzle clearance and throat diameter) and the flow characteristic. ey also suggested that the nozzle clearance has a significant influence on the flow velocity, and the larger the throat diameter is, the faster the mixing layer is developed [10].…”