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

Abstract

An experimental investigation was conducted to characterize the strand combustion of pure isopropyl nitrate (IPN) blended with a known de-sensitizer dibutyl sebacate (DBS). The blend was prepared with 75% IPN mixed with 25% DBS by weight so as to mimic the composition of Otto fuel II. Quartz tubes of 3, 5, 7.5, and 9 mm in diameters were utilized to create the strands of various diameters. The experiments were conducted in a quiescent atmosphere of air and the ambient pressure was varied from 5 to 40 bar in steps of 5 bar. Ignition of the strands was achieved by using a heated 60 μm Nichrome wire dipped in the liquid. The dependence of the linear burning rate of IPN-DBS blends on ambient pressure as well as the strand diameter was elucidated. The temperatures in the flame zone were measured with K-type thermocouples of 250 μm diameter. The ambient pressure variation was investigated for a strand diameter of 5 mm while, the tube diameter variation was studied at 5 and 40 bar pressure. The linear burning rate of IPN-DBS blends in 5 mm diameter tube was found to rise with pressure. The gas phase temperature above the tip of the tube was measured using 250 μm K-type thermocouple. The burning rate of IPN-DBS blends was found to be lower than that of pure IPN as well as Otto fuel II.