MECHANICAL ENGINEERING MS THESIS DEFENSE BY BERKE ÖZNALBANT

Title: Fuel Grain Modeling and Optimization for Hybrid Propulsion Systems using Additive Manufacturing

Speaker: Berke Öznalban

Time: August 10, 2023, 11.00

Place: Hybrid Meeting

Thesis Committee Members:

Assoc. Prof. Arif Karabeyoğlu (Advisor, Koç University)

Prof. Metin Muradoğlu (Koç University)

Prof. Onur Tunçer (Istanbul Technical University)

Abstract:

Hybrid propulsion systems have garnered significant interest in recent years due to their potential to offer a safer and cheaper alternative to traditional solid and liquid rocket engines. A key component of these systems is the fuel grain, which plays a vital role in the performance and efficiency of the propulsion system. However, the practical feasibility of hybrid propulsion has been hindered by the low regression rates. This thesis focuses on the improvement of regression rates in hybrid rocket fuel grains through the utilization of additive manufacturing. Acrylonitrile Butadiene Styrene (ABS) exhibits a lower regression rate compared to conventional fuels like paraffin or HTPB, making it a promising candidate for this study. Additive manufacturing allows for the production of complex geometries that were previously unattainable with traditional manufacturing techniques. This study explores the impact of the grid infill structure with different porosities on the performance of ABS fuel grains. Nitrous oxide was employed as the oxidizer for the firing tests of 3D-printed ABS fuel grains. The findings show that utilizing a lower infill ratio inside the fuel grain increases the regression rate significantly while ensuring combustion stability and structural integrity. The lower fuel mass caused by the porosities can be compensated using a fuel grain with a smaller port diameter without compromising strength.