TY - GEN
T1 - Flame and surface structure of laminate propellants with coarse and fine ammonium perchlorate
AU - Fitzgerald, R. P.
AU - Genevieve, P.
AU - Brewster, M. Q.
N1 - Funding Information:
Support for this work from the University of Illinois through the Department of Mechanical and Industrial Engineering and the Hermia G. Soo Professorship as well as the U.S. Department of Energy (UIUC-ASCI Center for Advanced Simulation of Rockets (CSAR)) through the University of California under Subcontract B341494 is gratefully acknowledged. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the U.S. Department of Energy, the National Nuclear Security Agency, or the University of California. Many thanks go to Ben Chorpening for his contributions to experimental imaging of pure binder laminates as well as to Greg Knott, Tom Jackson, and Pascal Genevieve for their work in developing the computational model.
PY - 2003
Y1 - 2003
N2 - The combustion of two-dimensional laminate propellants of ammonium perchlorate (AP) and hydroxyl-terminated polybutadiene (HTPB) is investigated experimentally and theoretically. The experiments use UV emission and transmission imaging to obtain simultaneous information about flame structure and burning surface profile for pressures ranging from 2 to 55 atm. The modeling uses numerical computations based on finite-rate chemistry with simplified kinetics and a free surface. Results show that flame-surface structure is a function of length scale (in this case, fuel-layer thickness), pressure, and equivalence-ratio disparity between the non-premixed fuel and oxidizer regions (binder-matrix equivalence ratio). Factors that promote split (diffusion) flamesurface structure are large length-scale, high pressure, and large equivalence-ratio disparity. The opposite factors (including oxygenating the binder) promote merged (premixed) flame-surface structure. For oxygenated binder loaded to the monomodal-AP limit (fine-AP/binder = 76:24) the transition thickness between split and merged structure is 5 to 10 times larger than that for pure binder. A correlation is shown between this transition and the optimal thickness that maximizes regression rate (at a given pressure). It has been determined both computationally and experimentally through the use of triple-layer laminates that the flame-surface structure at the center of the laminate is relatively uninfluenced by the outer boundary conditions. This provides firm justification for using the simpler, single fuel layer laminates to validate computational simulations through characterizing the effects of pressure, thickness, and binder equivalence ratio on flame and burning surface structure.
AB - The combustion of two-dimensional laminate propellants of ammonium perchlorate (AP) and hydroxyl-terminated polybutadiene (HTPB) is investigated experimentally and theoretically. The experiments use UV emission and transmission imaging to obtain simultaneous information about flame structure and burning surface profile for pressures ranging from 2 to 55 atm. The modeling uses numerical computations based on finite-rate chemistry with simplified kinetics and a free surface. Results show that flame-surface structure is a function of length scale (in this case, fuel-layer thickness), pressure, and equivalence-ratio disparity between the non-premixed fuel and oxidizer regions (binder-matrix equivalence ratio). Factors that promote split (diffusion) flamesurface structure are large length-scale, high pressure, and large equivalence-ratio disparity. The opposite factors (including oxygenating the binder) promote merged (premixed) flame-surface structure. For oxygenated binder loaded to the monomodal-AP limit (fine-AP/binder = 76:24) the transition thickness between split and merged structure is 5 to 10 times larger than that for pure binder. A correlation is shown between this transition and the optimal thickness that maximizes regression rate (at a given pressure). It has been determined both computationally and experimentally through the use of triple-layer laminates that the flame-surface structure at the center of the laminate is relatively uninfluenced by the outer boundary conditions. This provides firm justification for using the simpler, single fuel layer laminates to validate computational simulations through characterizing the effects of pressure, thickness, and binder equivalence ratio on flame and burning surface structure.
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M3 - Conference contribution
AN - SCOPUS:84894837636
SN - 9781624100994
T3 - 41st Aerospace Sciences Meeting and Exhibit
BT - 41st Aerospace Sciences Meeting and Exhibit
T2 - 41st Aerospace Sciences Meeting and Exhibit 2003
Y2 - 6 January 2003 through 9 January 2003
ER -