Flame Spread Pulsation Characteristics of Transformer Oil Vertical Spill Fire

Abstract

To investigate the effects of fuel discharge rate and initial fuel temperature on flame pulsation characteristics of vertical spill fire, a series of experiments under continuous leakage conditions are conducted on a specially designed experimental setup, for which transformer oil is selected as the fuel. Results show that the vertical spill fire burning area can be divided into three parts. Both the main flame and the flash flame are involved in the flame pulsation behavior, and the essence of the flame pulsation of the vertical spill fire is the periodic alternation of the diffusion flame and the premixed flame. Flame pulsation frequency shows a linear negative correlation with the fuel leakage rate, it decreases from 3.56 Hz (4.98 ml m−1s−1) to 2.439 Hz (15.93 ml m−1s−1), and it has a positive correlation with the initial fuel temperature. As the fuel discharge rate increases, the pulsation amplitude increases while the flame transient spread rate decreases, both of them have no significant correlation with the initial fuel temperature. The ratio of the average flame pulsation amplitude to the maximum pulsation amplitude is between 0.57 and 0.76. The flame transient spread rate shows a negative correlation with the fuel discharge rate, the maximum flame spread velocity reaches 3.17 m/s and 2.85 m/s in the growing phase and shrinking phase respectively. Due to the entrainment effect of the flame plume, the flame transient spread rate in the shrinking phase is higher than that in the growing phase. Analyzed the diffusion process of fuel vapor and the heat transfer mechanism of vertical spill fire, the control of fuel leakage rate and initial temperature on the flame pulsation characteristics is mainly manifested in its influence on the fuel evaporation and diffusion process and the length of preheating area. This work provides data supplement on the flame spread of liquid fuel spill fire.