Homi Bhabha National Institute (HBNI), IGCAR, Tamil Nadu, Kalpakkam, India
P. Mangarjuna Rao
Computational Simulation Section, Safety Engineering Division Fast Reactor Technology Group Indira Gandhi Centre for Atomic Research, Kalpakkam − 603102, India; Homi Bhabha National Institute, IGCAR, Kalpakkam, Tamil Nadu, India
Reactor Design & Technology Group, Indira Gandhi Center for Atomic Research, Kalpakkam, Tamil Nadu, India
The burning rate of pool fire and its interactions with the vent flow will decide the thermal transients inside a compartment and also the extent of fire hazard to the compartment. The flow of gas through the vents of a compartment induced by a thermal source is important in predicting the fire behaviour which influences the heat release rate of the fire and the combustion products formed. Also, the flow of air through the vents is very important in the design of natural ventilation systems. In this study, a 3D CFD-based numerical model has been developed to evaluate the thermal conditions inside a single vertical vent compartment with a known fire using Fire Dynamics Simulator (FDS) code. Numerical simulations were carried out for a diesel fire located in the middle of compartment with a vertical vent out in a 64 m3 room, in order to investigate the influence of vents on the thermal transients in a compartment. The pool fire is simulated using the specified heat release rate method based on experiments. The numerical predictions were compared with the benchmark experimental results. The main parameters of interest are the heat release rate, mass flow rate of the air, gas temperature variation along the height of the compartment, door way temperatures, ceiling gas temperatures and the average hot gas layer temperature variation with time. The available analytical correlations for the mass flow rate, gas temperatures are evaluated and compared with numerically predicted results. The grid sensitivity analysis is also carried out for obtaining the grid-independent results. This work can be extended to include simulations of a pool fire in a multi-compartment connected with vents, which is essential for reactor cells fire hazard analysis (FHA).