Experimental investigation on spark ignition of linear combustor at low pressure conditions

Abstract

In order to explore the influence of low pressure on ignition process, the ignition performance of a linear combustor with five burners was experimentally investigated at ambient temperature and low pressure. At air pressure drops of 1%, 2% and 3%, the influence of low pressure on the lower boundary of the ignition equivalence ratio and ignition delay have been carried, and the high-speed camera was used to record the flame propagation at various time. The results indicate that the minimum ignition equivalence ratio increases with the decrease of pressure. And, the lower the pressure, the more obvious the influence of pressure on the ignition boundary. At the same air pressure, the minimum ignition equivalent ratio decreases with the increase of the air pressure drop. For the process of ignition delay, the air pressure mainly affects the evaporation of droplets and the chemical delay process, and the air pressure drop mainly affects the physical delay stage. For the process of flame propagation, the flame moves between adjacent burners in a symmetrical pattern under various pressures. The air pressure mainly affects the ignition delay process, and the air pressure drop influences the ignition delay and the flame propagation in the early stage (the light-around from single burner to three-burners). The time needed to achieve stable combustion is the shortest at the air pressure drop of 2%.