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Presentation on UV emissions spectroscopy of the hydroxyl radical in PMMA hybrid rocket motor plumes.

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  • ASGC Presentation

    1. 1. Ultraviolet Emission Spectroscopy of the Hydroxyl Radical in Miniscale PMMA Hybrid Rocket Motor Exhaust Plumes Kellen Harkness Department of Chemistry Harding University ASGC Conference – 20 April 2007
    2. 2. Background <ul><li>Hybrid rocket motors </li></ul><ul><ul><li>Stable, cheap fuel </li></ul></ul><ul><ul><li>Need constant oxidizer flow for use </li></ul></ul><ul><ul><li>SpaceShipOne </li></ul></ul><ul><li>Harding’s involvement </li></ul><ul><ul><li>Development of spectroscopic method </li></ul></ul><ul><ul><ul><li>Miniscale </li></ul></ul></ul><ul><ul><ul><li>Safe </li></ul></ul></ul><ul><ul><ul><li>Inexpensive </li></ul></ul></ul><ul><ul><ul><li>Fast </li></ul></ul></ul>
    3. 3. Subject Matter <ul><li>Fuel: Polymethylmethacrylate (PMMA), or Plexiglas </li></ul><ul><ul><li>Transparent </li></ul></ul><ul><ul><li>Chemically simple, clean burning </li></ul></ul><ul><ul><li>Easy to obtain </li></ul></ul><ul><ul><li>Easy to machine </li></ul></ul><ul><li>Oxidizer: Gaseous oxygen </li></ul><ul><ul><li>Chemically simple </li></ul></ul><ul><ul><li>On hand </li></ul></ul>(C 5 O 2 H 8 ) n + 6 n O 2 -> 5 n CO 2 + 4 n H 2 O
    4. 4. UV Emission Spectroscopy <ul><li>What is it? </li></ul><ul><ul><li>Measurement of electronic transitions </li></ul></ul><ul><li>The hydroxyl radical </li></ul><ul><ul><li>Formed by several reactions </li></ul></ul><ul><ul><li>Common, high energy intermediate for combustion processes </li></ul></ul><ul><ul><ul><li>A 2 Σ  X 2 Π </li></ul></ul></ul><ul><li>Common problems </li></ul><ul><ul><li>“ Gaussianization” </li></ul></ul><ul><ul><li>Self-absorption </li></ul></ul>
    5. 5. Experiments Performed <ul><li>Irradiance vs. Oxidizer flow rate </li></ul><ul><li>Irradiance vs. Time </li></ul><ul><li>Mapping the plume for · OH concentration </li></ul>
    6. 6. Instrumentation & Setup <ul><li>Rocket motors </li></ul><ul><ul><li>PMMA </li></ul></ul><ul><ul><ul><li>100 mm length </li></ul></ul></ul><ul><ul><ul><li>6.35 mm bore </li></ul></ul></ul><ul><ul><li>Rocket stand </li></ul></ul><ul><ul><ul><li>Adjustable in two directions </li></ul></ul></ul><ul><li>Spectrometers </li></ul><ul><ul><li>StellarNet EPP2000 UV-Vis </li></ul></ul><ul><ul><li>StellarNet EPP2000 UV5-HR </li></ul></ul><ul><ul><li>Viewing area: 8 mm 2 </li></ul></ul>
    7. 7. Data Collection Software <ul><li>SpectraWiz </li></ul><ul><ul><li>Collect data from spectrometers </li></ul></ul><ul><ul><li>Exports to file </li></ul></ul><ul><li>Matlab </li></ul><ul><ul><li>Integrate spectral data </li></ul></ul><ul><ul><li>All spectra integrated from 306.24 nm to 324.57 nm </li></ul></ul><ul><ul><li>Used the trapezoidal rule for integration </li></ul></ul><ul><li>Excel </li></ul><ul><ul><li>Correlation </li></ul></ul><ul><ul><li>Illustration </li></ul></ul>
    8. 8. Results <ul><li>Effect of oxidizer flow rate on irradiance </li></ul>
    9. 9. Results <ul><li>Mapping the plume for · OH radical </li></ul><ul><ul><li>Measured in a 2D planar grid </li></ul></ul><ul><ul><ul><li>6.35 mm spacing radially, 12.7 mm spacing axially </li></ul></ul></ul>
    10. 10. Results <ul><li>Effect of burn time on irradiance </li></ul><ul><ul><li>Linear relationship </li></ul></ul>
    11. 11. Conclusions <ul><li>Effect of oxidizer flow rate </li></ul><ul><ul><li>Irradiance is highest at around 0.017 mol/s O 2 </li></ul></ul><ul><li>Mapping the hydroxyl radical </li></ul><ul><ul><li>The hydroxyl radical can be found in a smaller envelope than the visible area of the plume </li></ul></ul><ul><ul><li>Irradiance peaks close to 25 mm axial distance, 0 mm radial distance </li></ul></ul><ul><li>Effect of time </li></ul><ul><ul><li>Irradiance generally increases linearly with time </li></ul></ul>
    12. 12. Future Studies and Ideas <ul><li>Thrust measurements </li></ul><ul><ul><li>Farbar, E.; Louwers, J.; Kaya, T.; “Investigation of Metallized and Nonmetallized Hydroxyl Terminated Polybutadiene/Hydrogen Peroxide Hybrid Rockets”, Journal of Propulsion and Power, Vol. 23, No. 2 </li></ul></ul><ul><li>Temperature measurements </li></ul><ul><li>Spectroscopy of other gases/materials </li></ul>
    13. 13. References <ul><li>Wilson, Edmond W., Jr.; Mackey, James E.; Keller, Brett D.; Goertzen, Elaine J.; Clements, Sheryl A.; Rivenbark, Charles F., II; Cox, Calvin; “OH Emission Spectra of Hybrid Rocket Motors using PMMA and HTPB,” 41 st AIAA/ASME/ASEE Join Propulsion Conference, Tucson, AZ, 10-13 July 2005 </li></ul><ul><li>Dieke, G.H.; Crosswhite, H.M.; 1961 J. Quant. Spectroscp. Radiat. Transfer 2 97 </li></ul><ul><li>de Izarra, Charles; “UV OH spectrum used as a molecular pyrometer”; J. Phys. D: Appl. Phys. 33 (2000) </li></ul><ul><li>Pellerin, S.; Cormier, J.M.; Richard, F.; Musiol, K.; Chapelle, J.; “A spectroscopic diagnostic method using UV OH band spectrum”, J. Phys. D: Appl. Phys. 29 (1996) </li></ul>
    14. 14. Acknowledgement <ul><li>Arkansas Space Grant Consortium </li></ul><ul><li>NASA/EPSCoR </li></ul><ul><li>Harding University </li></ul><ul><li>Dr. Wilson </li></ul>

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