Article ID Journal Published Year Pages File Type
270419 Fire Safety Journal 2007 11 Pages PDF
Abstract

Computational fluid dynamics (CFD) calculations were carried out to design total flooding fire tests in a 28 m3 compartment for an ultra fine water mist (<10 μm). The exit momentum of the mist produced by a proprietary ultrasonic generator technology was extremely low with a mist discharge velocity below 1 m/s. The mist was discharged with multiple floor outlets equally spaced around the centrally located 120 kW pool-like gas fire. The transport of mist and its interaction with the fire was simulated by Fluent, a commercial CFD model. Lagrangian Discrete Phase Model (DPM) was used for droplets. Simulation predicted extinguishment within 10 s with a mist delivery rate of 1 l/min. However, in total flooding fire tests conducted, extinction times were more than 5 min. Additional computations approximating the ultra fine mist (UFM) as a dense gas agreed well with the observed transport timescales of minutes indicating that UFM behaves like a gas. Further, the mist–fire interaction needs a multi-phase Euler–Euler approach with a droplet vaporization model.

Related Topics
Physical Sciences and Engineering Engineering Civil and Structural Engineering
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