Influence of injection parameters on combustion time of boron particle in hot gas flow

Abstract

The basic experimental studies on boron combustion are done with the same general scheme of the experiment. Boron particles are injected in to flat flame burner products with a help of the transporting jet of a cold nitrogen, boron particle combustion process is registered with a number of optical methods. It is proposed that boron particle is injected in to the main hot gas flow instantly, combustion takes place at flame temperature and predefined oxygen concentration, influence of the transporting cold nitrogen jet is ignored. Recent combustion models are based mostly on that type of experiment and characterized with high complexity and low prediction level. In our study we reconstruct particle injection conditions for several basic experimental papers. It is shown that in all experimental setups ignition, combustion and even total particle burn out takes place in a wake of cold nitrogen jet. This area is characterized with much lower gas temperature and oxygen concentration than the main flat burner flow. Total temperature decrease can be about several hundred degrees, oxygen concentration can be seriously 30-50% lower than used in previous analysis of experimental result. Ignition and transition to second stage of combustion temperatures are found with a help of the test particle trajectory and temperature tracking. It is shown that analysis of boron particles injection influence on gas temperature and oxygen concentration is obligatory for future combustion model.