Examining Port Geometry/Solid Loading for Additively Manufactured Fuels in Hybrid Rockets
Gregory Young, Terrence L. Connell, Kyle Fennell, Steve Possehl, Michael J. Baier
Abstract
In this study, the effects of fuel port geometry and fuel additives on the performance characteristics of additively manufactured solid fuels in a hybrid rocket are explored. Static rocket motor firings were used to examine the performance characteristics, such as fuel regression rate and efficiency. Using a baseline fuel of poly(methyl methacrylate) (PMMA), a traditional center-perforated fuel grain as well as elliptical and swirl-elliptical port geometries were considered. The effect of aluminum as a solid fuel additive to the center-perforated fuel grain and the swirl-ellipse geometry was also investigated. Custom 3-D printer filament was developed, enabling the manufacture of fuels containing 10 and 25 wt % nano-aluminum as well as 25 wt % micron-sized aluminum allowing for a direct comparison of aluminum particle concentration and size. The swirl-ellipse geometry alone improved regression rates by about 35%, while exhibiting similar efficiency as the center-perforated fuel grain. The combination of the addition of nano-aluminum and the swirl-ellipse geometry resulted in an overall regression rate increase of about compared to the baseline PMMA center-perforated grain geometry.