ATOMIZATION CHARACTERISTICS OF HIGH?FLOW VARIABLE?ORIFICE FLOODING NOZZLES

Abstract

Droplet spectra factors for variableorifice flooding nozzles in quasistatic air were investigated to possibly aidthe reduction of spray drift, and to provide a basis for future atomizer design. A laserdiffraction instrument measured thedroplet size spectra of water sprays through orifices with diameters ranging from 1.14 to 6.35 mm. Spray discharge flow ratesup to 40 L min 1 were measured with a Coriolistype sensor. Nozzles produced an array of droplet size spectra with volumemedian diameters (Dv0.5) ranging from 296 to 1062 m. For singleorifice flooding nozzles, orifice diameter was the mostimportant factor positively correlated with droplet size spectra factors, except the Dv0.9. For flooding nozzles utilizing twoorifices in series, the magnitude of difference between the two orifice diameters was the most important factor positivelycorrelated with droplet size spectra factors. In addition, twoorifice flooding nozzles had strong negative correlationsbetween pressure and droplet size factors, whereas singleorifice flooding nozzles had strong positive correlations betweenflow rate and droplet size factors. A unique flowpressure phenomenon, in which flow decreased or remained steady withincreasing pressure, was observed for some orifices and pressures, possibly due to orifice inlet limiting conditions. The useof regression coefficients predicted most droplet size spectra factors with coefficients of determination (r 2 ) ranging from 0.72to 0.91, except for low r 2 values (0.11 to 0.50) associated with the Dv0.9 of singleorifice nozzles.