EFFECT OF SURFACE ROUGHNESS ON ATOMIZATION CHARACTERISTICS OF PREFILMING ATOMIZER

The influence of surface roughness on the breakup mode and atomization behavior of prefilming atomizers was investigated experimentally. A prefilmer, defined as a nozzle that generates a thin fuel film subsequently sheared into droplets at the trailing edge by high-speed airflow, was examined under varying roughness conditions. The characteristics of liquid accumulation downstream of the prefilmer and the wave dynamics of the liquid film were quantitatively analyzed, along with droplet size measurements in the secondary atomization region. The results reveal that surface roughness significantly affects the liquid accumulation area and plays a pivotal role in the initial atomization process. Two distinct breakup modes were identified: liquid film breakup and accumulation breakup, with lower surface roughness favoring the former. Increased surface roughness leads to a thicker liquid film, higher surface wave frequency, and reduced breakup length. However, due to the considerable distance of the secondary atomization region from the prefilmer, roughness exhibits minimal influence on the downstream Sauter mean diameter (SMD). Additionally, at a fixed air velocity, variations in fuel flow rate do not affect the SMD in the secondary atomization region. These findings offer insights for optimizing the design and performance of prefilming atomizers in practical engineering applications.