| Compressed air foam systems (CAFS) has been reported as a newly developed high performance technique for fire fighting. The systems are characterized by a substantial delivery momentum, high stability of compressed air foam ( CAF ), narrow distribution of bubbles sizes, wide foam expansion ratios by adjusting flow rate of foam solution and compressed air for suppressing different kinds of fires.The present paper describes the construction of an experimental device of CAFS. The experimental study isabout the basics of classifying the pattern of compressed air foam, foam properties, deciding optimum flow parameters of compressed air and foam solution working in the CAFS, and designing of mixerin CAFS.Characters of CAF are swayed with many factors.The mixing method of compressed air and foam solution, area of jet flow in mixer as well as mixing pressure were found to be key elements, which influence foam quality and fire-retardation properties.Basing on strong supports of experimental data, this paper ascertains the lowest acceptable concentration of foam solution when CAF is for the use of fire suppression and establishment of fire break and the concentration range of foam solution for generating dry or wet foam.Flow parameters of compressed air and foam solution are critical to types and performances of CAF. The experimental system is able to generate different flow patterns of gas-fluid two-phase and different types of compressed air foam. Analyses of numerous experimental data, induces mathematic equation of dividing line of the pattern of CAF and educes dependent relationship of compressed-air output and foam solution flux. These will be of great importance to design series of applied CAFS for forest fire suppression. |
