Droplet combustion of kerosene augmented by stabilized nanoaluminum/oxidizer composite mesoparticles

摘要

Inclusion of energetic and chemically active nanoparticles into liquid fuels and propellants is known to affect resultant combustion dynamics. Recently, the activity of such nanoparticle additives has been promoted using electrospray to preassemble said particles into nitrocellulose-bound mesoparticle (MP) clusters of either nanoaluminum (nAl) or oxygen-carrying nanoparticle primaries. In either case, stability in kerosene with TOPO surfactant and isolated droplet burning rates estimated in a free-droplet combustion experiment increase substantially with the MP additive architecture. Burning rates benefit from violent physical mixing of droplet systems which occurs when the carried nanoparticles are energetic and/or chemically active, causing gas generation, additive transport to the flame, energy or oxygen release, and further gas liberation accelerating the process. In this study, this same physical underlying mechanism is seen superimposed with the effects of another advantage of electrospray particle assembly: MP composition flexibility. By mixing nAl with oxide nanoparticles to form composite MPs, these novel additives for hydrocarbons are employed to modify kerosene and their effects are found to be dependent on the oxidizer chosen. Most notably, nAl/CuO MPs show evidence of interparticle thermite reaction in the droplet system yielding a cooperative benefit of the two constituents relative to either alone in MPs. Use of oxidizer co-additives and the MP architecture with nAl represents a flexible and promising method of overcoming low burning rates of hydrocarbons with high as-received nAl loadings and provides expansive means of tunability to tailor nanofuel properties. (C) 2019 The Combustion Institute. Published by Elsevier Inc. All rights reserved.