Physical characteristics on high-pressure combustion and propelling process of bulk-loaded energetic liquid

Abstract The objective of this study is to analyze high-pressure combustion characteristics of liquid propellant and projectile motion problem of the bulk-loaded propellant gun (BLPG). The BLPG described utilizes a mixture of hydroxyl ammonium nitrate and hydrocarbon fuel to replace gunpowder typically used in such guns. The motivation for such a development is to discard the need for a shell casing whereby carrying only propellant and bullets will reduce both the mass and volume per shot. The combustion processes of the bulk-loaded energetic liquid propellant are transient and mainly controlled by turbulent mixing of gas–liquid, thus resulting in the instability of interior ballistics of the BLPG. In this work, direct measurements of the pressure variation and projectile velocity with multiple chamber geometries on the combustion process of bulk-loaded liquid propellant are performed using quartz pressure transducer and timing device. The results indicate that better ballistic repeatability is achieved with the stepped-wall structure for the combustion chamber of the BLPG and a useful degree of controlling pressure oscillation is also achieved by this stepped-wall geometry. Moreover, based on this background, the numerical simulation is devoted to a special combustion issue under transient high-pressure and high-temperature condition, namely studying steady combustion mechanism in a stepped-wall combustion chamber with full monopropellant on one end of that is stationary and the other end can move with a high speed. The numerical results present utilizing the stepped-wall geometry in the combustion chamber itself can exert boundary control on combustion evolution during part of the interior ballistic cycle and the steps can induce an increase in the radial turbulent flow components causing a faster burn time to the chamber wall that lead to a reduction in the gas–liquid surface area, which is the postulated source of instabilities that have resulted in pressure variations.