Combustion Characteristics of Ramjet Fuel Grains with Boron and Aluminum Additives

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Combustion Characteristics of Ramjet Fuel Grains with Boron and Aluminum Additives

Jung, Woosuk / Baek, Seungkwan / Park, Juhyeon / Kwon, Sejin

An experimental investigation of the effect of boron (B) and aluminum (Al) additives to fuel-rich propellant for a solid fuel ramjet application was performed. In this research, depending on the composition of metal particles, three types of fuel grains with 15 wt % ammonium perchlorate particles were prepared and tested. To provide a short ignition delay, an ignition support material consisting of $NC / {BKNO}_{3}$ and a composite propellant were coated on the fuel grain. For the test, an oxidant gas having a controlled temperature and pressure and an oxygen composition close to that of the air in a ramjet combustor was supplied using an ethanol-blended hydrogen peroxide ( $H_{2} O_{2}$ ) gas generator. Air simulant gas was supplied with an average mass flow rate near $150 g / s$ and a Mach number of 0.21 in the fuel grain port. Through the test, the noticeable effect of B particles on combustion was confirmed by a high regression rate over $0.5 mm / s$ and combustion efficiency over 80%. Al particles were not effective additives individually; however, Al particles contributed to the ignition of B. In addition, metal oxide particle deposits on the nozzle confirmed the existence of a two-phase flow.