Since its inception, metal 3D printing has found many useful applications in the field of astronautical engineering and rocket fabrication. One such component that has been a topic of interest is the rocket fuel injector, a component critical to the rocket’s combustion efficiency and performance. Since the first successful hot-fire test of a metal 3D printed injector in 2013, advancements in metal additive manufacturing are continuously being made, allowing for accessibility and practical usage among private companies and government entities alike.
This dissertation investigates the applications of metal AM techniques to rocket swirl injector design and its effect on injector performance. Research into different types of metal AM techniques was conducted, followed by a comparative analysis of these techniques and commonly used metals available for commercial use from companies such as Xometry and Protolabs. Furthermore, an examination of the mathematical fundamentals of swirl injector geometric parameters and performance characteristics was performed. This combined with the acquired knowledge of metal AM techniques and metals, enabled the design of both a swirl injector and manifold assembly that was subsequently tested.
Cold flow testing of the metal 3D printed swirl injectors, including layer thicknesses of 30 μm and 60 μm, along with an FDM PLA print of a layer thickness of 0.10 m were conducted across multiple trials to produce a scatter plot and extrapolate an average mass flow rate and discharge coefficient. The results indicated that layer thickness affects these two performance characteristics, with the greatest mass flow rate and discharge coefficient being achieved by the metal injector of 60 μm. However, limitations including budget and timeframe were noted, which prevented a proper testing system and precise measurement devices from being utilised. Nevertheless, the findings recorded and evaluated within this study serve as an excellent foundation for future research into metal AM applications for rocket fuel injectors.