SPRAY CHARACTERISTICS AND ENERGY ANALYSIS OF N-HEPTANE ATOMIZATION BY HEATED AIR IN A MINI AIR-BLAST ATOMIZER

Abstract

Liquid fuel atomization plays an important role in fuel combustion of gas turbine engines and internal combustion engines. To reveal the interaction of atomizing air temperature (AAT) and air-liquid mass ratio (ALR) during the air-blast atomization process, <i>n</i>-heptane atomization in an air-blast atomizer is carried out experimentally at AAT &#61; 300 K-450 K and ALR &#61; 0.9-2.9. The spray cone angle (&phi;) presents a three-stage featured with rising ALR and enters the stable stage of 25&deg;-26&deg;. ALR played a decisive role in droplet size and velocity, while the AAT effect is ancillary and has a notable performance at part of conditions. The AAT effect on droplet size is more obvious at low ALR, while the effect on droplet velocity is strengthened as ALR increases. The same conclusion is also obtained in the analyses of droplets kinetic energy and surface energy. This discovery inspires us to increase AAT to compensate for the atomization performance decrease caused by reducing ALR. It can reduce the air pump load while stabilizing the atomization performance for large air mass flow condition. Even at low liquid mass, increasing AAT yields a visible improvement.