Effect of Acoustic Atomization on Combustion Emissions

Measurements of droplet characteristics and gas-phase chemical composition are reported for spray flames produced by a velocity-modulated, pressure-jet atomizer. A piezoelectric driver was used to modulate the velocity of kerosene fuel through a commercially available pressure-jet nozzle. Phase Doppler interferometry was used to me a sure droplet size and velocity in the spray flames. Gas samples were extracted from the spray flames, and concentrations of chemical species were determined using FTIR spectroscopy and a chemilumine scent NO/NOx analyzer. Experiments were performed at two different piezoelectric driving frequencies and compared to a base case without velocity modulation. The effect of velocity modulation on both the spray characteristics and chemical product formation were studied. The results show that velocity modulation decreases overall droplet size and increases mean droplet velocity and number density near the spray. These characteristics increase the flame standoff distance and flame length. However, the spray characteristics resulting from velocity modulation decreases the number of droplets escaping the spray flame unburned.