Expansion of Insoluble Gas Nucleus in Delayed Expandable Foam

摘要

Delayed expandable foam (DEF) is a new material that can significantly extend the range of foam curtain in electromagnetic waves interference, fire extinguishing and pollution wash down, etc. This paper studied the expansion of insoluble gas nucleus (IGN) in supersaturated solution of DEF. The radius and volume of IGN as well as DEF was calculated using double membrane model of mass transfer. Results show that the size of IGN raises steadily over time meanwhile the bulk volume of DEF is nearly invariable when both initial radius r_0 and number density ψ of IGN are small enough. This is called the volume sensitivity effect. At this stage, the time delay reduces linearly with r_0 and the square root of ψ. Accordingly, the time delay of DEF expansion can be adjusted by setting initial radius and number density of IGN. This research can provide theoretical basis for DEF development.