Experimental Study of Vapor Plume Motion and Flame Propagation Characteristics During Ignition of Oil on a Hot Flat Surface

In the aircraft engine, auxiliary power unit and other areas, hot surfaces are generated due to fuel combustion, power transmission and other reasons. Meanwhile, these areas may have the potential for oil leakage. When the leaked oil contacts these hot surfaces, it may be ignited to form a fire, threatening the aircraft’s safety. In this paper, evaporation and ignition experiments of oil leakage on a flat hot surface were carried out, and the vapor plume movement and flame propagation characteristics were investigated. Furthermore, the relationship between the hot surface temperature and the ignition core height and ignition delay time was studied. By the PIV technique, the velocity distribution of the vapor plume was studied. The flame transient development process and the flame propagation speed were quantitatively analyzed. The results show that the vapor plume velocity increased rapidly with height, then remained relatively stable, and eventually decreased gradually. Overall, the plume velocity shows a “cap-shaped” horizontal distribution. After ignition, the flame first expands in a spherical shape and then propagates in the vertical direction. The vertical upward propagated flame velocity is greater than the downward, and the corresponding velocities are 100.6 ~ 496.42 cm/s and 66.71 ~ 192.51 cm/s, respectively.