Simplified Modeling Of Sprinkler Head Fluid Mechanics
Free (open access)
249 - 260
T. M. Myers, A. W. Marshall & H. R. Baum
Simplified modeling of sprinkler head T. M. Myers, A. W. Marshall & H. R. Baum University of Maryland, College Park, USA Abstract Understanding the atomization of fire sprinkler sprays fills a critical gap in the modeling of fire suppression systems. Previous research by the authors has shown instability models and spatio-stochastic transport models can paint most of the sprinkler spray picture, but require input in the form of thickness and velocity of unstable fluid sheets. The model outlined makes use of a free streamline model of the flow which can be constructed based on a description of the water jet as a potential flow. The free stream-lines separating the jet from the surrounding air take the form of vortex sheets with the air assumed to be at rest. Any solution so obtained is an exact solution of inviscid flow equations with interior flow an exact solution to the Navier-Stokes equations. There is considerable literature describing two-dimensional free streamline flows, with most problems being solved through the use of the hodograph method. In three dimensions, the hodograph method and complex variable techniques are no longer available.Instead a mathematical model can be formulated using Green’s functions in conjunction with free streamline constant pressure assumptions regarding the surface of the flow. The resulting mathematical model allows for the determination of a flow field over a sprinkler head of arbitrary geometry and input conditions. Knowledge of the sprinkler head flow field provides insight into the impact of sprinkler head geometry and fluid velocity as well as providing the necessary inputs for a complete spatio-stochastic model of fire sprinkler sprays. Keywords: atomization, fire, fluid potential, free stream, Green’s function, spray, sprinkler.
Keywords: atomization, fire, fluid potential, free stream, Green’s function, spray, sprinkler.