טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentBresler Jacob
SubjectInvestigation of ABS-Paraffin based 3-D Printed Hybrid
Rocket Fuels
DepartmentDepartment of Aerospace Engineering
Supervisor Professor Benveniste Natan


Abstract

Hybrid rocket systems possess significant performance and safety benefits over both solid and liquid propellant systems.  Despite these advantages, widespread implementation has not yet been achieved due to the low regression rates exhibited by classical fuels such as HTPB, PMMA, Polyethylene, etc.  For over 20 years, it has been known that n-paraffin based fuels could overcome these regression issues, allowing also for significantly reduced manufacturing costs.  Unfortunately, paraffin-based fuels have not seen extended use because of their poor mechanical properties. The use of a combination of a strong polymeric skeleton, like honeycomb or similar, with paraffin could significantly improve the mechanical properties while maintaining the high regression rate of paraffin.

The work presented in this thesis is an investigation of the combustion properties of paraffin grains with embedded structures composed of acrylonitrile butadiene styrene (ABS), manufactured using a Fused Deposition Modeling 3D printer.  The process used for manufacturing these structures does not add any hazards to the overall manufacturing and at no point would specialized equipment or facilities be required.  The goal of this research was to investigate the effect of the skeleton on the regression rate of the grain and the combustion efficiency.

Testing was conducted on the hybrid test stand at the Fine Rocket Propulsion Center using gaseous oxygen as oxidizer.  The addition of the skeleton like structure to the fuel grain was found to increase the regression rate of the paraffin from approximately 1 mm/s for the baseline tests to 1.4-1.6 mm/s for the grains containing embedded structures.  This increased regression rate was accompanied by significant improvements in both the mixing and combustion efficiencies of the paraffin combustion process, which would allow for smaller post combustion chambers to be used in a full scale system.

No research similar to this has been reported in the literature.  Additionally, these were the first experiments conducted at the Technion that utilize additive manufacturing to improve the performance of paraffin wax.