PIV Measurements of Droplet Transport in a Homogeneous Turbulent Flow over a Cylinder

Abstract

Particle image velocimetry (PIV) measurements were carried out in the droplet-laden, homogeneous turbulent flow over both an unheated and heated cylinder, and body-centered cube (BCC) arrangement of spheres. Transport of both water droplets and aerosol particles was characterized upstream and downstream of these obstacles. Data were recorded for the cylinder at ambient temperature and after being heated to 423 K to estimate the effects of the hot cylinder surface on droplet transport. The results indicate that smaller droplets are entrained into the recirculation region behind the cylinder while the larger droplets impact the cylinder surface, accumulate and drip off, and/or rebound off the surface and disperse radially outward into the free stream. The Weber number was too low to lead to droplet shattering. Significant cooling of the cylinder surface from the initial preset temperature, which resulted from spray impingement, was observed for the heated cylinder, in addition to the presence of a vapor stream downstream of the cylinder along the shear layer region between the recirculation zone and free stream. For the BCC (with a blockage ratio of about 64 %), there was both transport of droplets and seed particles around and through the BCC, as well as significantly more liquid accumulation and dripping than for the cylinder.