Simultaneous Measurements of Drop Size and Velocity in Large-Scale Sprinkler Flows Using Particle Tracking and Laser-Induced Fluorescence.
Simultaneous Measurements of Drop Size and Velocity in
Large-Scale Sprinkler Flows Using Particle Tracking and
Putorti, A. D., Jr.; Everest, D. A.; Atreya, A.
NIST GCR 03-852; 56 p. July 2003.
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sprinklers; drop sizes; lasers; fluorescence; velocity
This paper reports an experimental technique that is
developed for instantaneous planar measurement of
droplet size and velocity for dilute sprays in general
and sprinkler sprays in particular. This particle
tracking technique relies on photographic measurements
of two-color fluorescence or fluorescence and Mie
scattering from droplets to determine their size and
velocit),. Measurements were made in a plane that passes
through the vertical axis of symmetry of an
axis-symmetric sprinkler spray. Drop velocities and drop
sizes down to 200 ~m were measured from the digitized
double-exposed photographs of sprinkler sprays. The
directional ambiguity was resolved by color
differentiation. A combination ot-fluorescence and Mie
scattering was investigated for a 250 mm x 350 mm
measurement area, while two-color fluorescence was
investigated for 460 mm x 540 mm measurement area. Dye
selection and concentrations were determined by testing
the fluorescence output of various water tracer dyes.
Collection optics and laser powers were varied to
optimize the color differentiation and maximize the
resolution for drop size measurements.