METHODS TO INCREASE VELOCITY OF MAKEUP AIR FOR ATRIUM SMOKE CONTROL - A CFD STUDY

Abstract

NFPA 92 currently restricts the velocity of makeup not exceed 1.0 m/s in atria smoke control systems. This requirement imposes a restriction on atria design due to the need for large area makeup vents. The objective of the research project is to evaluate the effects of velocity and location of makeup airflow on potential design fires within atria using Fire Dynamics Simulator 6.0 (FDS). A series of simulations are developed with fire size, makeup air vent flow velocity, and makeup air vent location as primary variables. The numerical results are analyzed in terms of possible adverse changes on smoke layer depth and fire spread propensity. The analysis is formulated in terms of a simplified engineering design tool, which allows for makeup air to exceed the 1.0 m/s limitation. The design tool proposed determines a modified volumetric exhaust rate for the system configuration, by a factor related to the smoke production increase.