The laser- and pressure-driven thrust response functions of HMX (cyclotetramethylene tetranitramine) at pressures near 1 atm were measured during laser-supported combustion at mean CO2 laser heat fluxes of 35 and 60 W/cm2. During laser-driven testing, the laser flux was modulated at ±15 W/cm2 at driving frequencies ranging from 4 to 250 Hz. Pressure-driven thrust measurements were made with a 10% peak-to-peak variation about the mean chamber pressure at driving frequencies ranging from 4 to 100 Hz. Measured steady-state temperature profiles and numerical predictions of the temperature profiles in the gas-phase reaction zone were used to estimate steady and unsteady heat feedback, respectively. Trends in the experimental results are consistent with a condensed-phase response to the unsteady heat fluxes and with results in the literature from similar experiments. Differences in trends with changing mean heat flux between the laser- and pressure-driven results are explained using the unsteady heat feedback estimates. The experimental results are compared to an analytical model, which used one-step reactions in the condensed phase and gas phase, and numerical modeling results that used detailed gas-phase chemistry. The agreement between the analytical model and the data was found to be better than that between the numerical modeling results and the data.
All Science Journal Classification (ASJC) codes
- Aerospace Engineering
- Fuel Technology
- Mechanical Engineering
- Space and Planetary Science