Combustion of AP/HTPB laminate propellants

M Quinn Brewster, G. M. Knott, B. T. Chorpening

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The combustion of AP/HTPB laminate propellants has been investigated experimentally and theoretically. The experiments used simultaneous UV emission and transmission imaging to obtain information about the flame structure and the burning surface profile. The modeling used both analytic calculations based on simple Shvab-Zeldovich mixing theory with finite Peclet number and numerical computations based on finite-rate chemistry with simplified kinetics and a free surface. Both pure and oxygenated binders (loaded with fine AP) were considered. Variations in Peclet number and O/F ratio were achieved through varying binder thickness and fine-AP loading. The experimental images made it possible to see the spatial relationship between the diffusion flame structure and the nonplanar contour of the burning surface. The free-surface model showed the ability to correctly predict relative protrusion and recession of AP and binder as well as diffusion flame shape. Both experimental and theoretical results showed that fine-AP loading has a pronounced effect on the UV-active diffusion flame structure. For the same approximate binder thickness and Pe, adding fine-AP to the binder causes the flame height to decrease and the leading edge to shift from the AP region toward the AP/binder interface, in accordance with Shvab-Zeldovich mixing theory. Binder width and pressure also affect diffusion flame structure in a predictable manner for both pure and oxygenated binders: increasing binder width increases the height of the UV-active diffusion flame while pressure has a weak effect. Numerical simulations, however, show that pressure has a strong effect on the leading edge of the diffusion flame, in terms of increasing volumetric heat release rate, which translates into increased burning rate. The simulated steady-state burning rate pressure sensitivity is found to be in the same range as the experimental observations, 0.3 to 0.5, without the use of arbitrary, non-integer overall reaction orders, only bimolecular kinetics.

Original languageEnglish (US)
Title of host publication37th Joint Propulsion Conference and Exhibit
StatePublished - 2001
Event37th Joint Propulsion Conference and Exhibit 2001 - Salt Lake City, UT, United States
Duration: Jul 8 2001Jul 11 2001


Other37th Joint Propulsion Conference and Exhibit 2001
CountryUnited States
CitySalt Lake City, UT


ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Aerospace Engineering
  • Control and Systems Engineering
  • Electrical and Electronic Engineering
  • Mechanical Engineering

Cite this

Brewster, M. Q., Knott, G. M., & Chorpening, B. T. (2001). Combustion of AP/HTPB laminate propellants. In 37th Joint Propulsion Conference and Exhibit