ChBE Seminar Series: Andre Marshall
Tuesday, November 2, 2010
11:00 a.m.-12:15 p.m.
Room 2110, Chemical and Nuclear Engineering Bldg.
Professor Sheryl Ehrman
A Comprehensive Methodology for Characterizing Sprinkler Sprays
Department of Fire Protection Engineering
University of Maryland
Sprinklers are widely used in fire suppression applications. The suppression performance of these sprays is determined by their ability to penetrate the fire to reach burning surfaces below, while dispersing water throughout the hot fire environment. Spray penetration and dispersion are governed by the initial drop size and velocity characteristics of the spray, which depend on the injection conditions and sprinkler configuration. In this study, the initial spray is fully characterized using a laser-based shadowgraphy and particle tracking velocimetry system producing nearly a million simultaneous drop size/velocity realizations for each sprinkler spray. Near-field spray characteristics are established from local measurements, which are mapped in a spherical coordinate system consistent with the kinematics of the spray. A novel data compression scheme is introduced to generate analytical functions describing the sprinkler spray based on the measurements. These functions are useful for initiating the sprinkler spray in computational fluid dynamics (CFD) based spray dispersion and fire suppression modeling. This framework also reveals physical characteristics of the initial spray not easily recognized from raw data. The near-field spray measurements and associated data compression approach are validated by comparing volume density measurements 1 m below the sprinkler with volume density predictions generated from spray dispersion calculations initiated with the analytical spray functions.