Particle behavior in solid propellant rocket motors and plumes

Abstract

The particle size distribution inside the combustion chamber and the changes that occurred across the exhaust nozzle were measured in a subscale solid propellant rocket motor with a 2% aluminized end-burning propellant grain and a highly underexpanded nozzle. A combination of diagnostic techniques were used. Size distributions in the exhaust plume were determined by a Single Particle Counter, a Malvern 2600 ensemble particle sizer, and by Scanning Electron Microscope (SEM) examinations of particles collected on a timed exposure impact probe. Size distributions inside the combustion chamber were determined by Malvern 2600 measurements through windows at the nozzle entrance, SEM examinations of particles collected from the nozzle entrance wall, and exhaust plume measurements of a helium quenched motor. It was determined that agglomeration processes dominated in the flow from the center of the combustion chamber up to the nozzle entrance. Particle breakup processes dominated particle behavior from the nozzle entrance, through the nozzle, and into the exhaust.