Spectrally Analyzed Embedded Infrared Fiber Optic Diagnostic of Advanced Composite Propellant Combustion

摘要

This is the final report for a program to extend an embedded- infrared-fiber propellant strand burning diagnostic by replacing bandpass filter detection by spectral detection. This work builds on previous investigations into the chemical and physical processes occurring in the condensed phases of nitramine advanced composite propellants, in which we observed decomposition product gases by infrared absorption in a small volume below the flame front. Detection of infrared absorption spectra along with video camera and embedded thermocouple records allows characterization of the evolution of decomposition regions by correlating time, spatial location, temperature and decomposition species fractions. Much of the effort of the program went into optimizing the sensitivity of the FTIR spectrometer/fiber optic apparatus, and into constructing test articles. The difficulty of these tasks limited us to only a handful of successful burns. The spectra obtained clearly show N2O and CO2, thus confirming our earlier work and adding a new species to those detected previously. Evidence for other gases is less certain.