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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.


pdf icon 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.