Uniformity of swirled sprays formed with nozzles of varying surface roughness

Nonuniformity of hollow conical sprays has been determined experimentally f or different values of surface roughness of the injection nozzle of swirl a tomizers. The discharge coefficient of the atomizers has also been evaluate d for the different surface roughnesses. Nonuniformity was found to be enha nced as the surface roughness of the nozzle increased. The extent over whic h the nonuniformity persisted, however, decreased with increase of the surf ace roughness. A nonuniformity parameter was defined to characterize the ma ss flow variations along the circumference of the spray. Sprays having nonu niformity coefficient less than 0.02 were seen to be formed when the thickn ess of the liquid film in the nozzle exceeded the surface roughness by a fa ctor of about 1000.