Burn rate characterization of desensitized isopropyl nitrate blends

A study regarding the linear burning rates of strands of blended liquid monopropellants was conducted in a pressurized vessel. The blends consisted of the monopropellant isopropyl nitrate (IPN) and the desensitizer dibutyl sebacate (DBS) while an established monopropellant Otto fuel II (OF-II) was also tested. Additional experiments were performed to determine and compare the temperature profiles in the liquid and gas phases of the propellants under study using S-type thermocouples. The study was conducted in a quiescent atmosphere of air with the ambient pressure varying within the range of 10-100 bar. The liquid strands were created using quartz tubes with an inner diameter of 5 mm and a thickness 1 mm. Profiles of regressing surfaces and the derived burning rates were plotted with pressures varying from atmospheric to 100 bar for IPN-DBS blends and OF-II. Furthermore, the experimental results of IPN-DBS blends have been compared against the theoretical predictions of a semi-empirical model, with a reasonable match between the two. A blend of 90% IPN with 10% DBS (by mass) was found to be an excellent candidate to replace OF-II.