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COLLEGE OF ENGINEERING Chemical, Biological & Environmental Engineering Background Mathematical Pressure Model • Chamber pressure → launch altitude • Three important pressure regions • Pressure model based on simplified mass balance • M = fuel grain and oxidizer mass • = oxidizer flowrate • = combustion products flowrate Testing and Data Collection Setup Fuel Development: Where to Start? • Literature: paraffin wax base, metal additives • Strong reducing agents: LiAlH 4 , CaH 2 • Require safe handling procedures = − HYBRID ROCKET FUEL DEVELOPMENT E. Allan-Cole, C. Truong, A. Vazquez, M. Wilson Sponsor: Dr. Nancy Squires Methods Additives were handled in a purge bag filled with an inert gas (N 2 ). Paraffin wax was grated to decrease the melting time. Additives were then added to molten wax in purge bag. Fuels were then poured into Solo cups and allowed to cool. Fuels were re-melted and casted using a lathe to achieve a cylindrical shape. Hybrid Motors • Solid cylindrical fuel grain (approx. 700 g) • Liquid oxidizer (N 2 O) • Fuel/oxidizer separation allows for oxidizer flow adjustments • Melt layer – small liquid droplets sheared from fuel grain surface → greater surface area, faster combustion. OPPORTUNITY The hybrid team has not fully explored the use and performance of hybrid rocket solid fuels. ISSUE The OSU American Institute of Aeronautics and Astronautics (AIAA) student rocketry team is designing, building, and launching a hybrid rocket for the first time in school history. OBJECTIVE Develop and create two recipes for solid hybrid rocket fuel. Collect experimental thrust data to assess fuel performance. Hybrid Rocket Motor – liquid oxidizer flows through combustion chamber and reacts with solid fuel. Exhaust gas exits through nozzle. Fuel Grain L = 12”, D = 2” Melt Layer Small liquid droplets result in greater surface area Results Acknowledgments • Dr. Squires (MIME) - Project sponsorship and background info • OSU CBEE, MIME, AIAA - Sponsorship and funding • Max Flansberg – Project direction • Dr. Harding - Project support, class instruction Paraffin/LiAlH 4 fuel has a higher total impulse than paraffin/Al fuel. Investigation of different compositions of LiAlH 4 is recommended. Conclusions Experimental test stand and subscale motor (left) and nitrous oxide supply system (right). Tubing and valves connect the N 2 O tank to the subscale motor. Methods Thrust Results and Total Impulse • LiAlH 4 → higher thrust • Al → more even burn, lower thrust Chamber Pressure (psig) Burn Time (s) Chamber Pressure (psig) Burn Tests • 1 g sample burned • Longest sustained burn: - Re-melt LiAlH 4 @ 350 s Burn test experimental set up 20 wt% Aluminum 14 wt% LiAlH 4 (foamy) 14 wt% LiAlH 4 (re-melt) 14 wt% CaH 2 40 wt% gasoline Napalm Original Recipe 12% LiAlH 4 30% Aluminum 250 200 150 100 50 0 0 1 2 3 4 5 6 7 8 9 10 817 lbf•s 534 lbf•s Time (s) Thrust (lbf)
