Citation

Prahl JM, Wendt B. Fire Safety J. 1988; 14(1-2): 101-111.

Copyright

(Copyright © 1988, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The discharge flow pattern from fire sprinkler heads in modeled in a nondimensional description which emphasizes a sprinkler's ability to evenly distribute spray over a maximum possible floor area. An axisymmetric model sprinkler, consisting of a jet impinging normal to and at the center of a flat disk, employs the disintegration of the resulting film to produce the droplet sprays. Measurements of the sheet breakup radius show that it is proportional to the negative one-third power of the Weber number based on jet diameter. The discharge distribution is varied by controlled axial vibrations of the disk. Nondimensional sheet breakup radii and radial flow distributions correlate with the ratio of the disk driving frequency to the frequency of maximum growth of sinuous waves. Flow patterns from the model apparatus are compared with those from a commercial fire sprinkler. An analytical model to predict droplet trajectories and consequent discharge distributions shows qualitative agreement with the measured flow patterns for an assumed Rosin-Rammler droplet size distribution about a volume mean droplet diameter in the accepted range of previous investigators.