Wavelength-modulation spectroscopy in the mid-infrared for temperature and HCl measurements in aluminum-lithium composite-propellant flames

This work presents the design, development, and application of a laser-absorption-spectroscopy diagnostic capable providing quantitative, time-resolved measurements gas temperature HCl concentration in flames metallized composite propellants containing ammonium perchlorate (AP) hydroxyl-terminated polybutadiene (HTPB). utilizes quantum-well distributed-feedback diode laser emitting near 3.27 ?m to measure absorbance spectra using scanned-wavelength-modulation-spectroscopy technique that is insensitive non-absorbing transmission losses caused by metal particulates flame. was applied characterize spatial temporal evolution mole fraction small-scale AP-HTPB either an aluminum-lithium alloy or micron-scale aluminum. Experiments were conducted at 1 10 atm. At both pressures, flame propellant, on time-averaged basis, 80 200 K higher than aluminum propellant (depending location flame) indicating more complete combustion. In addition, reached values 65–70% lower conventional aluminum-propellant highest measurement The pressures showed similar trends reduction but elevated this occurred length scale nearly order magnitude smaller atmospheric pressure. results presented further support use effective reducing produced without compromising performance, thereby making it attractive additive for solid rocket propellants.