Laser diagnostic measurement of solid propellant flame structure for model validation

This paper describes ongoing research efforts directed at understanding the fundamental mechanisms controlling the deflagration of solid propellants which define the ballistic performance. Advanced laser diagnostics are applied to one dimensional and multi-dimensional solid propellant flames. Diagnostics applied include Planar Laser Induced Fluorescence imaging of 2D species and temperature profiles, Raman spectroscopic measurement of majority species absolute concentration profiles, UV-Visible absorption spectroscopic measurement of species number density, and micro-thermocouple measurements of temperature profiles. These techniques are applied to neat energetic materials, such as RDX, as well as composite propellants based on ammonium perchlorate (AP) oxidizer with hydrocarbon fuels. The composite oxidizer/fuel flames are studied in both multi-dimensional sandwich configurations as well as a one dimensional counter flow diffusion flame configuration. Diagnostic measurements of species and temperature profiles are compared with models based on detailed kinetic mechanisms. Experimental and model limitations that limit the quality of the results are discussed. It is shown that the most useful results are obtained when experimentalists, kineticists, and modelers are involved in the experiment design from the very beginning.