1. Student: C1C Tim Brown Advisor: Maj. Lydon Fast Burning Hybrid Fuels

2. Preview Motivation Fuel Burning Theory Objectives Predictions Cavitating Venturi Experimental Test Set-Up Results Conclusions

3. Motivation There is growing emphasis on safety, environmental cleanliness, low cost, and safety. Hybrids suffer from low regression rates Advantages over solids Advantages over liquids ThrottlingSimpler SafetyCheaper Restart/Shut- down

4. 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.

5. 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

6. 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

7. 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:

8. Predictions Motor Number12345 Initial Mass (kg)0.4620.50.6140.6250.823 Initial inner port diameter (cm)2.54 2.862.54 Length (cm)8.41 10.510.613.8 Chamber Pressure (kPa)2068.4 3447.4 4826.3 O/F ratio5.8 6.31 Isp (s)240.5 255.4 262.6 Thrust (N)384.8 524.9 660.6 mdot ox (kg/s)0.14 0.18 0.22 c* (m/sec)1622

9. 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.

10. 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

11. 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.

12. Results

16. Motor Number12345 Final Mass (kg)0.3030.3590.4790.3660.538 Final inner port diameter (cm)4.464.425.124.174.9 Chamber Pressure (kPa)21201774269821793114 O/F ratio2.73.954.031.893.22 Isp (s) 97103151101136 Thrust (N)175170276220340 mdot ox (kg/s)0.135 0.1490.1440.194 c* actual (m/sec)8197491032704872 Efficiency0.5050.4620.6360.4340.538 rdot (mm/s)4.433.52.875.283.63 rdot using web thickness (mm/s)2.632.222.652.222.5 rdot assuming 5% loss of final mass (mm/s)4.123.162.315.013.38 Gox (kg/m-s^2)131.19131.89111.62154.31162.4

17. 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.

18. 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

19. Questions?