Fuel Regression Characteristics of Axial-Injection End-Burning Hybrid Rocket Using Nitrous Oxide

• Published in: Journal of propulsion and power 2022-09, Vol.38 (5), p.759-770
• Main Authors: Okuda, Ryota, Komizu, Kodai, Tsuji, Ayumu, Miwa, Takumi, Fukada, Mai, Yokobori, Shuichi, Soeda, Kentaro, Kamps, Landon, Nagata, Harunori
• Format: Article
• Language: English
• Subjects: Combustion; Firing (igniting); Fuel regression; Fuels; Nitrous oxide; Oxidizing agents; Oxygen; Rockets; Storage vessels; Weight reduction
• ISSN: 1533-3876; 0748-4658; 1533-3876
• DOI: 10.2514/1.B38318

This is an investigation of fuel regression characteristics in an axial-injection end-burning hybrid rocket using nitrous oxide. Experiments were conducted using 38 mm cylindrical fuel grains with an array of 0.8 mm ports made from curable resin. Previous studies of end-burning hybrid rockets used gaseous oxygen as oxidizer. Nitrous oxide may be more suitable than gaseous oxygen for use in space-based missions because of the weight savings associated with the oxidizer storage vessels, supply system, and motor mass. In this study, two types of nozzle closures were employed to increase the initial chamber pressure and promote the formation of stabilized combustion in multiport fuels. The results of 12 firing tests showed that the regression rates when using nitrous oxide as the oxidizer were as high as that from previous research (0.61–4.5 mm/s at 0.25–0.75 MPa) using gaseous oxygen as the oxidizer. These high regression rates were nearly five times higher than that of experiments using single-port fuels. It is clear from a visualization experiment that fuel flakes break off and travel downstream in solid form during firing, which could cause the fuel regression rate of multiport fuels to be higher than that of single-port fuels.