Design of Smoke Ventilation System for the Kolkata Metro Station Using Computational Fluid Dynamics

Metro Railway in Kolkata is the oldest metro system in India. The Metro Railway Kolkata was constructed progressively from 1972 to 1995, Phase-I a length of 3.04Kms. from Esplanade to Bhowanipur having been completed in 1984. Full length of 16.45Kms was commissioned in 1995. The existing stations and tunnels of Metro Railway, Kolkata are not equipped with effective emergency ventilation system. The project objective was to retrofit the ventilation system to vent out smoke in case of fire scenario in subway station premises. The existing ventilation system is equipped to supply only normal ventilation for human comfort and physiological requirements. The supply air is provided by air-conditioned inlet openings in the station with a capacity of 120 CMS. CFD (Computational Fluid Dynamics) tool FDS (Fire Dynamic Simulator) was used to achieve the capacity and location of emergency ventilation system in the station. Since it was a retrofit job, a lot challenges were faced due to limited space availability. Various design options were evaluated to come up with the optimum design within the given constraints. In the final design Over track exhaust (OTE) was introduced to vent out smoke in case of emergency. The optimized design system can effectively evacuate the smoke, reduce the contamination of poisonous gases and to improve the visibility level inside the underground station to provide assistance to fire fighters by providing a clear smoke free path to approach the fire location. The paper includes the design philosophy used for emergency ventilation system design. The usage of CFD in evaluating the various design options. The CFD simulation results for various successful and unsuccessful cases.