Combustion studies of laminate propellants of AP and HTPB with UV/IR imaging and spectroscopic diagnostics

The flame and burning surface structure of laminate propellants has been investigated using ultraviolet and infrared emission imaging as well as infrared imaging spectroscopy of emission and absorption. Laminates of hydroxyl-terminated-polybutadiene (HTPB) and ammonium perchlorate (AP), which are a geometric simplification of heterogeneous propellants, allow a more fundamental investigation of effects of pressure and AP particle size on overall combustion behavior.; Studies of the flame and burning surface structure through the imaging of electronically excited OH have concentrated on quantifying regimes of premixed and non-premixed combustion for oxygenated binder (loaded with 2-mum AP particles) laminates at pressures of 1-55 atm. General results follow similar trends of pure binder laminates in that higher pressure and larger fuel-layer-thicknesses lead to split, protruding fuel layers supported by leading edge diffusion flames; however the transition thickness at which the regimes change is an order of magnitude larger for oxygenated binder laminates. A correlation between the transition conditions and the optimal thickness maximizing burning rate has been found, verifying the usefulness and necessity of validating computational models with the regime data if full predictive capability is to be obtained.; Infrared images of burning laminates have also been captured at wavelengths over a range of emitting vibrational-rotational transitions of hydrogen chloride (HCl) near 3520 nm. Supplemented by imaging spectroscopy at 3300-3900nm, the spatial extent and general source of emission have been determined. Emitting HCl is prevalent throughout the burning gap, while continuum emission is the primary source of emitted intensity in the diffusion flame and the intermittent flamelet near the leading edge. This flamelet has been observed to support and regulate a relatively unstable burning surface at pressures near 4.4 atm.; A non-intrusive diagnostic technique of imaging spectroscopy has been developed and used to study vibrational-rotational transitions of HCl in order to measure associated temperatures at different locations in the gas phase and to test for thermal equilibrium. Experimental spectra have been compared with results from a spectral model to reveal that the path of observation is neither optically thin, nor isothermal.