고산소-저기압 환경에서 JetA1 액체연료의 최소 점화에너지 측정 및 고체연료의 화염전파 특성에 관한 연구

Abstract

In the present study, the ignition characteristics of liquid fuel and flame spread on solid fuel were experimentally investigated under atmospheric conditions similar to those inside the first stage of launch vehicles. To quantify ignitability as ignition characteristics, the minimum ignition energy (MIE) for liquid fuel was defined and measured under elevated oxygen concentrations and reduced atmospheric pressures which are the most probable conditions during the space launch vehicle’s operating process. The experimental results demonstrate that the measured MIE decreased with increasing the oxygen concentration for given atmospheric pressures. When the atmospheric pressure was reduced from 1 atm to 0.2 atm at the fixed oxygen concentration, the measured MIE was found to vary with P-2 but the lowest MIE was observed at 0.8 atm. The characteristics of flame spread were also investigated to provide fundamental knowledge to prevent fires and explosions of vehicles during launching operations. To this end, the rate of flame spread on the solid fuel was measured at elevated oxygen concentrations and reduced atmospheric pressures. A 0.18 mm diameter optical fiber was used as a solid fuel. The experimental results indicated that elevated oxygen concentrations can increase the rate of flame spread while increasing the atmospheric pressures to 1 atm can lead to decreases in the rate of flame spread. The increases in the rate of flame spread with pressure is due mainly to reductions in the convective heat loss that are clarified through an analysis of the pressure dependence on the convective heat transfer coefficient.