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Detonation Research for Propulsion Applications

Detonation Research for Propulsion Applications. J. E. Shepherd, E. Schultz, J. Austin, T. Chao, E. Wintenberger, P. Hung Graduate Aeronautical Laboratories California Institute of Technology Pasadena, CA 91125 USA.

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Detonation Research for Propulsion Applications

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  1. Detonation Research for Propulsion Applications J. E. Shepherd, E. Schultz, J. Austin, T. Chao, E. Wintenberger, P. Hung Graduate Aeronautical Laboratories California Institute of Technology Pasadena, CA 91125 USA Sponsored by ONR MURI “Multidisciplinary Study of Pulse Detonation Engines” PSU/CIT/Princeton Team Midyear Review, San Jose, CA, February 10-11, 2000 California Institute of Technology Graduate Aeronautical Laboratories

  2. Activities at Caltech • Cellular structure characterization • Initiation • Diffraction • Structural and thermal response California Institute of Technology Graduate Aeronautical Laboratories

  3. Cellular Structure • Purpose: characterize detonations in JP-5, JP-8, JP-10 fuels (l measurement) California Institute of Technology Graduate Aeronautical Laboratories

  4. CIT 288-mm Detonation Tube Tube modifcations: 1. Redesigned using FEM 2. Stronger flange-tube connections 3. Thicker flanges 4. Double number of fasteners 5. Heating system a) 8 zones of control b) 10 kW total power 6. Higher temperature seals California Institute of Technology Graduate Aeronautical Laboratories

  5. Detonation initiation • DDT time scale analysis • Ideal vs real performance with DDT California Institute of Technology Graduate Aeronautical Laboratories

  6. DDT Scaling California Institute of Technology Graduate Aeronautical Laboratories

  7. Ideal PDE Impulse Computation by H. Hornung using Amrita (AMR) q/RT1 = 40, g = 1.2 Taylor-Zeldovich IC California Institute of Technology Graduate Aeronautical Laboratories

  8. Diffraction • Test series with H2, C2H4, C3H8 fuels • Ar, He, N2, CO2 dilution. • Model development California Institute of Technology Graduate Aeronautical Laboratories

  9. Structural response • Response of tube to detonation loading California Institute of Technology Graduate Aeronautical Laboratories

  10. CIT Presentations • Structural response (Joe Shepherd) • Diffraction (Eric Schultz) • DDT and ideal performance (Jo Austin) California Institute of Technology Graduate Aeronautical Laboratories

  11. Progress to Date • 288-mm tube modifications started • mechanical changes done • Diffraction study in 38-mm tube done • kinetics validation, model development • Preliminary DDT time scale study • Impulse, P(t) measurements initiated • 2D transient FEM studies California Institute of Technology Graduate Aeronautical Laboratories

  12. Structural Response of Detonation Tubes J. E. Shepherd, T. Chao, P. Hung - GALCIT California Institute of Technology Graduate Aeronautical Laboratories

  13. Goals • Modeling of thermo-elastic response of tubes to detonation loading • 3D FEM computations with imposed detonation or shock loading • Develop design criteria • Experiments to examine failure mechanisms and thresholds California Institute of Technology Graduate Aeronautical Laboratories

  14. Flexural Wave Excitation • Traveling loads (shock or detonation) excite flexural waves in tubes • Resonance associated with waves traveling at flexural wave speed • Deformations can be up to 4X static equivalent California Institute of Technology Graduate Aeronautical Laboratories

  15. Flexural Wave Excitation 1.5 mm thick steel tube, 25 mm F, 0.5 m long Critical velocity 927 m/s, shock speed 950 m/s 2D Axi-symmetric explicit FEM California Institute of Technology Graduate Aeronautical Laboratories

  16. Amplification factor Measured strain (hoop) 10-4 0 4 6 8 2 U (m/s) t (ms) Loading by Flexural Waves Experiments in Caltech 288-mm detonation tube California Institute of Technology Graduate Aeronautical Laboratories

  17. Future Directions • More realistic tube configuration • Use gas dynamic simulations to provide boundary conditions • Investigation of stress concentrations • Coupling to thermal effects • Comparison with measurements in model tubes California Institute of Technology Graduate Aeronautical Laboratories

  18. Schedule I California Institute of Technology Graduate Aeronautical Laboratories

  19. Schedule II California Institute of Technology Graduate Aeronautical Laboratories

  20. Schedule III California Institute of Technology Graduate Aeronautical Laboratories

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