The reaction of a fire plume to a droplet spray

The reaction of a fire plume to an applied water spray is crucial to fire suppression. While considerable research has been devoted toward fire plumes without suppression, and some computer simulations of fire suppression have provided insight, little experimental data exist detailing how the structure of a fire plume changes during suppression. Experiments were performed in which 5, 15 and 50 kW gas burner fires were exposed to a spray from one of three spray sources. Flow rates from the nozzles or fire sprinkler ranged from 6 to 106 L/min. Contours of infrared (IR) intensity of the fire plume show that the plume decreases in height and increases in width with the increasing strength of the applied spray. Based on the height of the maximum fluctuations of IR intensity, the thermal plume height decreases with increasing spray strength, but the overall projected area of the plume changes very little. The plume height depends on the ratio of the drag of the droplets on the air to the momentum of the plume, allowing the results to be generalized to typical fire suppression applications.