Effects of a Wire Mesh on Droplet Size and Velocity Distributions of Cryogenic Sprays

Cryogen spray cooling allows removing large amounts of heat in short periods of time. Previous investigations have shown that stainless steel wire meshes placed between spray nozzle and target surfaces effectively increase uniformity in lateral heat extraction while reducing cooling efficiency. In this study we used phase Doppler particle analysis to assess the effect of a wire mesh on the diameter and velocity radial distributions of cryogen droplets and, consequently, on the surface heat transfer. We measured at 40 mm downstream and various radial locations within steady state spray cones from two different nozzles without and with a mesh at two mesh-nozzle distances. Results show that with the mesh, droplets lose velocity and increase in size. The closer to the center of the spray cone the droplets are, the larger the loss in velocity. As a consequence, the radial velocity profile is more uniform relative to that without a mesh.