Ammonium perchlorate/(H₂ + CO) gaseous fuel diffusion flame studies

Counterflow diffusion flame experiments and modeling results are presented for a fuel mixture consisting of CO and H₂ flowing against decomposition products from a solid ammonium perchlorate (AP) pellet. The flame zone simulates the diffusion flame structure that is expected to exist between reaction products from fine AP crystals and a hydrocarbon binder with the decomposition products from large AP crystals, characteristic of a bimodal AP propellant. Quantitative species and temperature profiles have been measured for a mixture of two fuels, hydrogen and CO, and one strain rate, given by a separation of 5 mm, between the fuel exit and AP surface. Species measured included CN, NH, NO, OH, N₂, O₂, CO₂, H₂, CO, HCl, and H₂O. Temperature was measured using a combination of a thermocouple at the exit, spontaneous Raman scattering measurements throughout the flame, OH rotational population distributions, and NO vibrational population distributions. The burning rate of the AP was also measured for this flame's strain rate. The measured 12 scalars are compared with predictions from a detailed gas-phase kinetics model consisting of 86 species and 531 reactions. Model predictions are found to be in good agreement with experiment and illustrate the type of kinetic features that may be expected to occur in propellants when AP particle size distributions are varied.