CFD simulations of the effects of HVAC-induced flows on smoke detector response.

Rapid activation of fire protection systems in response to a growing fire is one of the important factors required to provide for life safety and property protection. Airflow due to the heating, ventilating, and air-conditioning (HVAC) system can significantly modify the flow of smoke along the ceiling and must be taken into consideration when a particular system is designed. At present, the standards used to guide the design of fire protection systems contain very little quantitative information concerning the impact of airflow produced by HVAC systems. This paper describes the results of a project that used computational fluid dynamics (CFD) to simulate smoke movement in response to H VAC-induced airflows. The HVAC simulations included ceiling-mounted slot diffusers, wall-mounted slot diffusers, high sidewall diffusers, and ceiling diffusers from which airflow drops to the floor, in combination with rectangular and slot returns. The CFD model was modified to calculate smoke detector activation times throughout the fire driven flow field.