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Strategies for 3D Printing Advanced Hybrid Rocket Fuel Grains and Hybrid-Like Liquid Rocket Motors_Additive Innovation_Fuller

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  • Jerry! Your works are very interesting and applicable onto Experimental Rocketry. I was engaged in similar systems (hybrid pure, tripropellent or Hybrid-Like Liquid Rocket Motor), have developed and have constructed (all Flight Models) 3 small thrust tripropellent hybrid-liquid rocket motors: Me_HL_100_001, Me_HL_50_001 y Me_HL_1000_001 (and more 10 FM of HRM). The majority of models used cast grains from "black paraffin". And here for Me_HL_1000_01 I would be prepare the grain at ABS+paraffin formula made using 3D printing technology. If you want, we can combine our works and efforts. I live in Argentina and I work in INVAP Space-Nuclear Company as space optical instruments adviser. I had very friendly and professional relations (to microhybrids rocket motor discussion) with Bill Colburn. Thank You very much for this publication. I get applicate that onto my work. Thank You very much for this publication. I get applicate that onto my work.
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Strategies for 3D Printing Advanced Hybrid Rocket Fuel Grains and Hybrid-Like Liquid Rocket Motors_Additive Innovation_Fuller

  1. 1. © 2016 The Aerospace Corporation Strategies for 3D Printing Advanced Hybrid Rocket Fuel Grains and Hybrid-Like Liquid Rocket Motors Jerry Fuller, Space Science Applications Laboratory The Aerospace Corporation October 19, 2016 jerry.k.fuller@aero.org
  2. 2. 2 Basics: Major Rocket Propulsion Systems  (A) Liquid - most capable, expensive – Saturn 5, Shuttle Main Engine  (B) Solid - cheap and simple, most common – Tactical missiles, Shuttle SRM Boosters  (C) Hybrid - safe, moderate expense, low performance (thrust, efficiency), rarely used (Virgin Galactic - SpaceShip 1, 2) Rockets are categorized by the phase states of their propellants. These states have a great deal to do with how a rocket is used. Oxidizer/ Fuel Mixture (Solid) Oxidizer (Liquid) Fuel (Solid) Valve Oxidizer Fuel Turbo- pumps (A) (B) (C)
  3. 3. 3 Hybrid Rocket Characteristics Typical Selling Points for Hybrid Rockets Advocates Like to say Hybrids:  Have Medium Performance (ideally near liquids)  Are Easily Shipped - “Responsive”  Can be throttled, re-lit like liquids  Simple, safe and inexpensive The truth is…  We can’t burn them fast enough (low thrust)  They are not as efficient as they should be Oxidizer Valve Fuel
  4. 4. 4 Fuel Grain Production – The Fundamental Problem A Simplified Explanation of Casting • Real castings often involve multiple ports, and stiffening webs • Mandrels must be simple shapes – No undercuts – Little surface area Mold or Liner Mandrel Propellant Grain Port
  5. 5. 5 How We Generally Think of Hybrid Rocket Combustion Similar illustrations appear throughout hybrid rocket literature • Generally we assume gas flow parallel to the fuel surface • We accept that convection will be weak • Burn rate is limited by how fast gases can diffuse across the Flame Pyrolysis by Radiation and Weak Convection Fuel Grain (often HTPB Rubber) FlameSheet Head End Radiation (weak) “Blowing” Conduction (weak) Oxidizer Nozzle End
  6. 6. 6 Traditional Techniques to Improve Performance The techniques used to improve performance have problems too  Wagon Wheel  Low mass fraction  Challenging Fabrication  Chunks and splinters  Swirl Injection  Effect dies out  Slicing and Stacking  Complex  Chunks  Paraffin (wax) as High Regression Rate fuel  Mechanically weak  Ejects unburned fuel (lowering Isp) Patent US5339625 A Patent US6601380 B2
  7. 7. 7 Printed Hybrid (and other) Rockets Major Advances Enabled by Additive Manufacturing
  8. 8. 8 Traditional versus Additive Manufactured Grain Printing allows port shapes that dramatically increase performance MJM Acrylic Fuel Grains • Same – Mass – Dimensions – Cross Section • Helical shape forces convection • Creates 25% more surface area • More efficient • Burns > Twice as Fast AM fuel grains move from Radiation to Forced Convection
  9. 9. 9 Printing Strategies Several Ways to Take Advantage of AM • Print the whole fuel grain – Seamless, monolithic, strong – ABS is as good as traditional HTPB, but… • Friendlier Chemistry – Stronger, Stiffer, Greener – Recyclable scrap • Print just the port, or port and shell – Cast paraffin, HTPB or other fuels – Use printed structures to manipulate oxidizer flow • Turbulence – inducing features • Swirl - inducing features Printed ABS Printed Paraffin Printed Turbulator/ Cast Paraffin
  10. 10. 10 Printing Strategies (cont’d) Several Ways to Take Advantage of AM • Print multiple fuels at once – MJM Acrylic/Paraffin – FFF Multi-Head extruders and Mixing Extruders • Print empty cells and fill with a solid or liquid fuel – Extremely high regression rates are possible – Very powerful fuels can be used • Print empty containers and fill with cast composite solid propellant – Propellants like APCP can be cast as traditional – May offer new grain shape opportunities to combine thrust and efficiency MJM Co-Printed Acrylic/Paraffin Printed Cell Structure for Liquids
  11. 11. 11 Printing Strategies (cont’d) Several Ways to Take Advantage of AM • Print hollow fuel grain • Use cast propellants – Less expensive (currently) – Print flow management features • Swirl, turbulence… – Include oxidizers to make new APCP motors • ABS extrusion temperature too hot for Ammonium Perchlorate • May be able to have higher thrust, longer burn Printed ABS/ Cast Paraffin
  12. 12. 12 Performance Characterization of Hybrid Rocket Fuel Grains with Complex Port Geometries Fabricated Using Rapid Prototyping Technology D. Armold, E. Boyer, B. McKnight, J. D. DeSain, J. K. Fuller, K. K. Kuo, and T. Curtiss International Journal of Energetic Materials and Chemical Propulsion, Vol.13, 2014 0.1 1.0 40 50 60 70 80 90 100 Acrylic Correlation Straight-Port ST-SW 1/8 tpi ST-SW 1/4 tpi ST-SW 1/2 tpi RegressionRate(mm/s) Oxidizer Mass Flux (kg/m 2 -s) 150 Hot-Fire Test Results – Acrylic MJM Increased regression rate through printed features
  13. 13. 13 Performance Characterization of Hybrid Rocket Fuel Grains with Complex Port Geometries Fabricated Using Rapid Prototyping Technology D. Armold, E. Boyer, B. McKnight, J. D. DeSain, J. K. Fuller, K. K. Kuo, and T. Curtiss International Journal of Energetic Materials and Chemical Propulsion, Vol.13, 2014 0.9 1.0 2.0 3.0 50 60 70 80 90 100 Paraffin Correlation SP TRB 1/2 tpi ST-SW 1/8tpi ST-SW 1/4 tpi ST-SW 1/2 tpi Swept HC 1/4 tpi Lg Swept HC 1/4 tpi RegressionRate(mm/s) Oxidizer Mass Flux (kg/m 2 -s) 150 Hot-Fire Test Results – Paraffin MJM Increased regression rate through printed features
  14. 14. 14 Performance Characterization of Hybrid Rocket Fuel Grains with Complex Port Geometries Fabricated Using Rapid Prototyping Technology D. Armold, E. Boyer, B. McKnight, J. D. DeSain, J. K. Fuller, K. K. Kuo, and T. Curtiss International Journal of Energetic Materials and Chemical Propulsion, Vol.13, 2014 2.0 3.0 4.0 40 50 60 70 80 90 100 Paraffin Correlation SP Paraffin SP Par80%/Al20% 1-V TRB Paraffin (1/4 tpi) 3-V TRB Paraffin (1/4 tpi) 1-V TRB Par80%/Al20% (1/4 tpi) RegressionRate(mm/s) Oxidizer Mass Flux (kg/m 2 -s) 1.4 150 Hot-Fire Test Results (cont’d) Increased regression rate through printed features
  15. 15. 15 Test Results- Effects of Pre-Heating Testing of Hybird Rocket Fuel Grains at Elevated Temperatures with Swirl Patterns Fabricated Using Rapid Prototyping Technology Brendan R. McKnight, Derrick Armold2, J. Eric Boyer3, and Kenneth K. Kuo4 John D. DeSain5, Jerome K. Fuller6, Brian B. Brady7, and Thomas J. Curtiss8 50th AIAA Joint Propulsion Conference Significant Increase in Regression Rate without Drop in Isp 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 40 50 60 70 80 90 100 200 Paraffin Correlation Cast Paraffin SP 22C Lg Swept HC 22C (1/4 tpi) Lg Swept HC 50C (1/4 tpi) Cast Paraffin SP 35C Cast Paraffin SP 55C RegressionRate,mm/s Oxidizer Mass Flux, kg/(m^2-s) AM enables faster burning, more efficient paraffin grains
  16. 16. 16 Combing Printed and Cast Propellants Significant Increase in Regression Rate without Drop in Isp Hollow AM grains with flow management features AM hollow grains • Provide Containment, Structure • Allow heating (energy efficient, faster burn) • Provide Flow Management Features (Turbulators, etc.) • Leave the port-positive in place or melt it away Pour (cast) Almost Any Propellant Print Almost Any Port Shape
  17. 17. 17 Combing Printed and Cast Propellants (cont’d) Significant Increase in Regression Rate without Drop in Isp Hollow AM grains with flow management features AM hollow grains accept propellants that are hard to “print” like APCP (ammonium perchlorate composite propellant): • Ammonium Perchlorate and some energetic additives degrade at FDM/FFF temperatures • Crosslinked, Thermoset, HTPB (if you must) • Mechanically weak propellants (paraffin, etc.) • Novel grain shapes realized through AM could allow almost any thrust profile Some Traditional Port Cast Propellant Shapes and their Thrust Profiles
  18. 18. 18 Combing Printed and Cast Propellants (cont’d) Significant Increase in Regression Rate without Drop in Isp Hollow AM grains with flow management features 0 50 100 150 200 250 300 350 400 450 0 2 4 6 8 10 12 14 ABS / Paraffin with Integrated 3-Fin Turbulator and GOX Pre Tank Post Tank Chamber Temp
  19. 19. 19 Combing Printed and Cast Propellants (cont’d) Significant Increase in Regression Rate without Drop in Isp Hollow AM grains with flow management features
  20. 20. 20 Large Printers are Now Capable of Launch Vehicle Size SEEMECNC’S “PARTDADDY” PHOTO COURTESY OF SEEMECNC • New, large format printers (industrial robots) eliminate size constraints for some fuels (CF/ABS) - VERY large prints are possible • Large enclosed printers can print 154Kg (340lb) ABS • Delta printers have stationary build platforms, enabling very large prints A LARGE FFF PRINTER BASED ON INDUSTRIAL ROBOTS PHOTO COURTESY LOCKHEED MARTIN CORPORATION. AN ENCLOSED CARTESIAN FFF PRINTER WITH A HEATED BUILD VOLUME PHOTO COURTESY OF COSINE ADDITIVE, INC. Print size – no longer a limitation
  21. 21. 21 Large Printers are Now Capable of Launch Vehicle Size 2-SEAT CAR BEING PRINTED ON BAAM PHOTO COURTESY OF CINCINNATI INC. • Cincinnati Inc’s BAAM, billed as Largest AM • Print envelope 20 x 7.75 x 6 feet • Carbon Fiber filled ABS material (probably capable of CF/Nylon) Print size – no longer a limitation BAAM PRINTER, PHOTO COURTESY OF CINCINNATI INC.
  22. 22. 22 Hybrid-Like Liquid Rocket Motors First steps toward a (printed) liquid motor in hybrid form
  23. 23. 23 Liquid-Enhanced Hybrid and Hybrid-Like Liquid Motors • Adding small amounts of liquid fuel – Increases combustion temperature, further increasing regression rate for the solid fuels – Increases solid fuel surface area as liquids are consumed • Adding large amounts of liquid fuel – Moves us toward a simpler liquid motor – Allows less expensive, more easily obtained fuels to be used – Will need significant research
  24. 24. 24 Hybrid-Like Liquid Motors Removing Turbopumps = Removing a Major Cost • Can Liquid Motors be made like Hybrids? • Expensive, highly refined “Rocket fuels” like RP1 are unnecessary – RP-1 used to lubricate pumps (typically no pumps on hybrids) – Jet A (commonly available kerosene) – “Bunker Fuel” (Alkane lengths of C= 12 – 70) – Biofuels Oxidizer Fuel Turbo- pumps Fuel Management Structures Fuel
  25. 25. 25 Fuel Metering Strategies • Tapered Port Wall • Stacked Cones • Spiral • Enhanced Hybrid (small amounts of liquid) C) Liquid-Enhanced Hybrid B) SpiralA) Stacked Cone
  26. 26. 26 Post Combustion Chamber Pressure Analogous to thrust, increases with added kerosene Adding kerosene significantly increases burn rate over solid ABS (blowout)
  27. 27. 27 Liquid Fuel Passive Metering Example: Triple Canted Helix + Tapered Port Wall Liquid Fuel Pours Into Port as Port Wall Regresses Thin Port Wall (top) Burns-Through First
  28. 28. 28 Liquid Fuel Passive Metering Example (cont’d): Triple Canted Helix, Tapered Port Wall Burned and Unburned Specimen (50mm diameter) Cut-away showing Canted Spiral and Tapered Port Wall
  29. 29. 29 Post Combustion Chamber Pressure Analogous to thrust, increases with added kerosene (blowout)
  30. 30. 30 Kerosene/SLA Triple Canted Helix, Tapered Port Wall, ~45 g Kerosene
  31. 31. 31 Conclusion (and Caveats) • Novel port shapes and design features are possible though AM • Regression rate (Thrust) can be Doubled • Specific Impulse (Efficiency) can also be increased • Launch-vehicle–size fuel grains are within reach • Inexpensive liquid motors may be possible • A small amount of liquid fuel can enhance Hybrids • Entirely new concepts like heated paraffin motors are enabled • These things are true for SMALL motors • Nobody knows how to passively control the flow of liquid fuel yet • More work is needed, especially at larger scales
  32. 32. 32 Acknowledgements: • The Aerospace Corporation – John DeSain, Brian Brady, Andrea Hsu, Tom Curtis, Cody Shaw, Kevin Dorman – The Aerospace Corporation’s Independent Research and Development program. • Pennsylvania State University
  33. 33. 33 Questions? jerry.k.fuller@aero.org 310-336-5027

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