Effect of an Alcohol Resistant Aqueous Film Forming Foam (AR-AFFF) on the Evaporation, Boiling, and Collision Dynamics of a Water Droplet on a Heated Solid Surface.
Effect of an Alcohol Resistant Aqueous Film Forming Foam
(AR-AFFF) on the Evaporation, Boiling, and Collision
Dynamics of a Water Droplet on a Heated Solid Surface.
(880 K)
Manzello, S. L.; Yang, J. C.
Journal of Colloid and Interface Science, Vol. 256,
418-427, 2002.
Keywords:
droplets; alcohol; aqueous films; aqueous foams;
evaporation; water droplets; heated surface
Abstract:
An experimental study is presented for droplets
containing an alcohol resistant aqueous film forming
foam (AR-AFFF) impacting and boiling on a heated
stainless steel surface. A solution of 3% (volume
fraction) AR-AFFF/distilled water was compared to
experiments with distilled water. In addition to these
solutions, 3% AR-AFFF/simulated seawater was used, since
for many naval applications, AR-AFFF is mixed with
seawater. The impaction process was recorded using a
high-speed digital camera at 1000 frames per second. For
each fluid, the droplet impact Weber number was fixed
and the droplet evaporation lifetime was measured as a
function of temperature. Collision dynamics were
investigated for each fluid with the temperature of the
stainless steel surface varied from film evaporation to
film boiling. It was observed that the addition of 3%
AR-AFFF to water reduced the temperature for departure
from nucleate boiling and the Leidenfrost point
dramatically compared to pure water. Droplets were
observed to breakup violently for solutions of AR-AFFF
mixed with simulated seawater at film boiling. The
results demonstrate that the collision dynamics depend
on what type of water is mixed with AR-AFFF.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899