Burn Rate Characterization of Iso-propyl Nitrate Blends: Part I

Abstract

An experimental investigation was conducted to characterize the combustion of a pure monopropellant isopropyl nitrate (IPN). Quartz tubes of 3, 5, 7.5, and 9 mm inner diameter were utilized to create the strands of varying dimensions. The experiments were conducted in a quiescent atmosphere of air and the ambient pressure was varied from atmospheric pressure to 40 bar in steps of 5 bar. Ignition of the IPN strands was achieved by using a heated 60 μm Nichrome wire dipped in the liquid. The dependence of the linear burning rate of pure IPN on ambient pressure as well as the strand diameter was elucidated. The temperatures in the flame zone and liquid phase were measured by K-type thermocouples of 250 and 75 μm diameters respectively. The ambient pressure variation was investigated for strand diameter of 5 mm, while the tube diameter variation was studied at 1, 10, 20 and 40 bar pressure. The linear burning rate of pure IPN strands of 5 mm diameter was found to exhibit staged behavior where a steep rise in burning rate with pressure was observed after an initial decreasing trend. The linear burning rate was found to reduce with increasing tube diameter. The effect of IPN monopropellant flame was prominently observed only for pressures higher than 10 bar.