A study of laser and pressure-driven response measurements for solid propellants at low pressure

This work was part of a larger program aimed at understanding and modeling propellant combustion and its interaction with changes in pressure and velocity in a typical rocket motor. A pressure driven combustion facility was developed and used to measure pressure-coupled amplitude and phase response during combustion of propellant samples at low pressure. Laser-driven experiments were also performed in a different chamber to measure propellant response at atmospheric pressure. A CO₂ laser was used to ignite and sustain combustion during laser and pressure-driven combustion and also served as a source of oscillatory laser flux during laser-driven combustion. The primary objective behind these laser-driven experiments was verification of the hypothesis in the literature that suggests the laser and pressure-driven propellant responses are analogous to each other.; Advanced homogeneous propellants like HMX and heterogeneous AP composite propellants were tested under laser and pressure-driven experiments at pressures of 1, 2 and 3 atmosphere.; One-dimensional energy balance analyses in addition to steady-state temperature measurements were used to evaluate the effects of condensed-phase heat release and gas-phase heat feedback on the propellant response amplitudes. Steady-state species measurements were used to validate gas-phase chemical mechanisms for HMX and the AP/HTPB propellants. These validated mechanisms were then used in a one-dimensional premixed flame code to obtain the steady and unsteady components of the gas-phase heat feedback.; Laser-driven response experiments on HMX showed that the response amplitude decreased with an increase in pressure. The unsteady component of the laser flux induces an unsteady component of the gas-phase heat feedback that is out of phase with the laser flux. Comparisons with the numerical data of BYUs' Erikson showed that the numerical model predicted a laser-driven response that is three times lower than the measured laser-driven response and predicts a pressure-driven response that is 50–70% lower than the measured pressure-driven response. Erikson believes this is due to poorly resolved condensed-phase kinetics and poor temperature sensitivity data. The analytical model of Culick also under-predicted the measured pressure-driven response profiles for HMX. Hence the analytical model of Iribicu and Williams was derived and provides reasonable agreement with the experimental values for pressure-driven response amplitude. (Abstract shortened by UMI.)...