Abstract: In order to explore the effect of high-temperature oil surface on aqueous film-forming foam (AFFF), a series of experiments using KI25X transformer oil and AFFF were carried out with a special experiment platform. The spreading parameters of AFFF at different initial oil surface temperatures were recorded to compared the spreading behaviors at different oil pool sizes (D=50 cm and 117 cm). The variation of spreading area and spreading rate were analyzed. Results indicate that the spreading shape of D=50 cm oil pool presents central symmetry, and the spreading rate has three stages: rapid increase, linear increase and slow increase. While in the D=117 cm oil pool, the spreading shape presents irregular characteristics, and only two stages of spreading rate: linear increase and slow increase. The initial oil temperature significantly affects the spreading characteristics of AFFF. When the oil pool diameter is D=117 cm, the spreading rate first rises and then decreases with the increase of oil temperature, and the average spreading rate reaches the maximum when the initial oil temperature is 60 ℃. A model for spreading rate is established based on the theory of oil surface spreading, and the foam friction parameter first increases and then decreases with the increase of oil temperature.

Key words: aqueous film-forming foam, foam spreading, oil surface temperature, foam friction parameter