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This research study explores the use of fast burning hybrid fuels for enhanced propulsion efficiency and reduced environmental impact. Detailed findings and conclusions based on experimental tests are presented, highlighting crucial advancements in fuel-burning theory and performance predictions.
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Fast Burning Hybrid Fuels ASTRO USAFA Student: C1C Tim Brown Advisor: Maj. Lydon
Preview • Motivation • Fuel Burning Theory • Objectives • Predictions • Cavitating Venturi • Experimental Test Set-Up • Results • Conclusions
Motivation • There is growing emphasis on safety, environmental cleanliness, low cost, and safety . • Hybrids suffer from low regression rates
Fuel burning theory Humble, R. W., Henry, G, N., Larson, W, J., Space Propulsion Analysis and Design, Space Technology Series, McGraw-Hill Companies, Inc.,1995.
Objectives • Vary oxidizer mass flow rates to find any oxidizer mass flow dependency • Test the hypothesis that paraffin wax offers high regression potential due to droplets which readily escape from a liquid layer on the surface into the flame zone where they can react with hydrogen peroxide • Calculate a and n from the following equation
Predictions A thermochemistry computer code provided our starting point. Assume: frozen flow, exit pressure of 82.7 kPa, 90% pure HTP, 95% paraffin wax and 5% carbon black One test for each different chamber pressure Gave optimum O/F ratio and predicted Isp GuiPep, Arthur J. Lekstutis, Traxel Labs Inc., Revision 0.04
Predictions • Thrust is adjusted to optimize fuel geometry. • Oxidizer mass flow rate is calculated from: • c* is calculated from the thermochemistry computer code where Isp is greatest. • Chamber pressures are based on oxidizer mass flow rates • Length is calculated from cylinder geometry:
Cavitating Venturi • To ensure that the mass flow rates of oxidizer were as desired during the experiment the cavitating venturi was calibrated at varying pressures using H20.
Experimental Test Set-up 2,000 psi nitrogen tank Water-cooled nozzle Purge system Oxidizer Fuel cartridges easily exchanged Spacer Data acquisition at 1,000 Hz
Experimental Test Set-Up Pressure transducers were inserted pre-CV, post-CV, and chamber The nozzle had a 1.1075 square inch exit area and a .1104 square inch throat area yielding an expansion ratio of 10.03.
Conclusion • Similar tests conducted by Stanford University using gaseous oxygen as the oxidizer achieved regression rates around 2.6 mm/sec for values of 130 kg/m^2-sec. Our regression rate is closer to 3.23 mm/sec for the value of 130 kg/m^2-sec. The hypothesis that paraffin is capable of a high regression rate, especially with hydrogen peroxide, was validated.
Conclusion • The main shortcomings were lower than expected , , and c*. • Difficulty of recovering specimen’s weight after firing as well as calculating web-thickness. Therefore included a 5% loss regression result which is still above expected