Combustion of Spherical Agglomerates of Titanium in Air. III. Motion of Agglomerates and the Effect of Blowing Velocity on Nanosized Combustion Products and Burning Time

The combustion of monodisperse titanium particles with a characteristic size of 38 and 320 μm moving in air was studied. Pyrotechnic samples generating monodisperse particles were burned in a chamber with a nozzle to impart an initial velocity to the burning particles. The particles were accelerated by the jet of gaseous combustion products discharged from the nozzle. The maximum path-averaged particle velocity relative to the ambient air was 7.9 m/s. Combustion of moving particles was carried out in a quartz tube 2 m long. At the end of the combustion, combustion products (oxide aerosol) were sampled from the tube using a thermophoretic precipitator. Size distribution functions of nanometer-sized spherule particles were determined by processing electron micrographs of samples. The velocity and burning time of burning particles were determined by video recording at a speed of 300 fps. It was found that increasing the velocity of motion of agglomerate particles with a diameter of 320 μm relative to the gas from 0.9 to 7.9 m/s leads to a decrease in the size of the spherules from 28 to 19 nm and to a decrease in the burning time from 0.45 to 0.26 s.