Fire Safety Science Digital Archive

The national capital of India, New Delhi has experienced a phenomenon growth in population in the last few decades. This resulted in development of rail based urban transport system for Delhi. The first phase of the project under execution comprises of 62.5 km of route length of which 12.5 km is underground and is called the Metro corridor. Therefore it becomes essential to study the evacuation procedures in this type of tunnel. Keeping this in mind, the present Research work is undertaken. The Proposed research work will investigate the fire dynamics in a section of underground tunnel, approximately similar to Metro corridor using Computational Fluid Dynamic (CFD) Technique. The objective of the paper is to evaluate the emergency ventilation strategies of a section of tunnel. All Metro underground stations are approximately 300 m long and 20 m wide. Ventilation fans are located at the stations and not inside the tunnels. For analysis, it is assumed that the fire source of 4 MW is located at the center of the tunnel. In the event of fire it is assumed that the train will pass through and reach the station. Hence, dynamics of fire inside tunnel without train is only studied. The numerical model used is first verified using experimental results from Steckler experiment. The model is then used to simulate the fire environment inside the tunnel. The results of CFD simulations are compared with those of empirical correlations available in the literature. The effectiveness of smoke ventilation system is then studied. For this the effect of ventilation flow rate, both uniform and non-uniform airflow in tunnel, on thermal environment inside the tunnel has been studied. This helps in determining the critical velocity necessary to prevent back layering. A ventilation scenario where both inlet and exhaust fans are activated is also studied.