Experiments have been made in the laboratory, in a ventilated small model rodyway, to explore the factors controlling the proportion of sprayed liquid converted into foam, the filling of the model roadway with foam and the back-pressure exerted on the ventilation by the net and foam-plug. The following conclusions are reached.
1) It is shown by experiments that there is an upper airspeed limit for adequate filling of the model roadway with foam, the limit being about 50m/min for one net design.
2) The degree of filling a model roadway with foam has been characterized by the “Leak ratio”.
3) The back-pressure of the net is comprised of two components. The first component (h1) is independent of airspeed. The second component (h2) is due to the aerodynamic resistance of the net and increases linearly with airspeed.
4) If the air speed through the roadway is constant, the degree of filling a roadway with foam is effected by the characteristces of the foam agents solusion.
