Boron Particle Nonequilibrium Effects in Combusting Ducted Flows

O design of air-breathing propulsion systems will require an adequate description of the mixing and combustion of ducted, fuel-rich, primary streams with secondary air. The primary stream will often contain metal particles such as boron, magnesium or aluminum. Development of a model has been previously reported' for describing combustion of a particleladen jet which is mixing with a subsonic secondary air stream in a duct. This model considered the particles to be in dynamic and thermal equilibrium. This synoptic summarizes an extension of this earlier model to include particle nonequilibrium effects. Particle drag, thermal lag, and particle ignition, melting, and combustion effects are considered. A series of parametric calculations for a typical boron-loaded, air-augmented system shows effects of particle size and secondary duct pressure on metal combustion efficiency. Methods of improving combustion efficiency at low pressure are briefly examined.