Development of Lattice-Augmented Fuels for Hybrid Rocket Applications
Hybrid rocket propulsion systems, which utilize a solid fuel and liquid oxidizer, are among the safest and simplest rocket propulsion systems that can be developed. Despite these attractive qualities, the commercialization of the technology has been slow due to difficulties associated with scaling designs from lab-scale demonstration motors to functional propulsion systems for launch vehicles. The introduction of liquefying solid fuels, such as paraffin wax, have helped overcome some of the scaling issues traditionally associated with hybrid rockets, but a number of key challenges relating to combustion efficiency and the structural properties of wax-based fuels remain. The current work explores these challenges through the use of an additively-manufactured lattice embedded within the fuel grain. A novel process of generating three-dimensional gyroid surfaces with the desired properties has been developed that allows for lattices to be manufactured using fused deposition modeling (FDM) from a variety of thermoplastics. The application of lattice-augmented fuels to hybrid rocket systems at a number of scales is considered. An extensive series of tests were conducted on an optically accessible slab burner to characterize the regression characteristics of lattice augmented fuels. Lattice-augmented fuels were also demonstrated at a larger scale using a 4-kN nitrous oxide/paraffin hybrid rocket motor. Studies at this scale analyzed the regression rate of the fuel as well as methods of improving the combustion efficiency. A passive mixing device located in the combustion chamber was used to improve the combustion efficiency of the wax-based fuel by over 40%. Finally, lattice-augmented fuels were demonstrated in-flight during a series of sounding rocket flights which compared the performance of non-augmented to augmented fuels. The thesis has shown that the proposed strategy for improving wax-based fuels using lattice-augmentation performs well across a number of motor scales and can be successfully applied to an operational hybrid rocket system.
hybrid rocket, propulsion, combustion
Hill, C. (2022). Development of Lattice-Augmented Fuels for Hybrid Rocket Applications (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.