Ignition and Combustion of Isopropyl Nitrate Sprays

Abstract

Experimental investigation of spray combustion of the monopropellant nitromethane (NM) assisted by a hot surface is presented. Spray combustion of NM was studied in a constant volume combustion chamber fitted with glow plugs within the chamber pressure range of 1 to 5 bar. The sprays were produced by injecting approximately 0.1 ml of the propellant through a commercial gasoline injector. Ignition was achieved by using two glow plugs placed in a horizontally opposed manner at a distance of 70 mm from the nozzle tip within the chamber. The pressure rise within the chamber was used to elucidate the ignition and combustion processes. The ignition delays were found to be in the order of milliseconds, with high heat release rates accompanying the combustion phenomena. The maximum differential pressures reached during combustion were found to increase with chamber pressure up to 3 bar, and decrease thereafter. The rate of pressure rise achieved after combustion were also found to be dependent on the initial chamber pressures. FTIR spectrometry of the combustion products yielded further insight into the reactions.