2015 年 50 巻 2 号 p. 255-261
In spray combustion, spray flame is formed in a position slightly away from an injection nozzle. In order to simulate spray combustion, it is important to predict precisely the distance called the flame lift-off length (set-off length). In this study, the effect of combustion conditions on the flame lift-off length was investigated using experimental results conducted with light oil and kerosene. A Single fuel spray was injected into a constant volume combustion vessel and self-ignited in high-temperature gas. Pressure, temperature, density of the internal gas, and injection pressure of the fuel were chosen as the combustion conditions considering the operation of the actual combustion equipment and engines. The combustion processes were observed with a high speed video camera. For the purpose of applying calculation models for the simulation of spray combustion, empirical formulas were derived. The formulas showed good correlation between the length and the combustion conditions. The formulas showed that the length of light oil is longer than that of kerosene only in the higher range of pressure and temperature of the ambient gas.