Studies on the performance of airblast atomizer under varying geometric and flow conditions

Abstract

Performance of an ah-blast atomizer operated at atmospheric pressure is evaluated through the drop size measurement using a laser light scattering system, Overall spray characteristics tie presented for varying mass flow rates of fluids and geometric parameters such as size of air nozzle, type of air approach passage (convergent and straight exit) and liquid post recess in the air nozzle cavity. The variation in Sauter mean diameter (SMD)’ in the spray is presented as a function of velocity ratio, relative air velocity, mass ratio, and momentum ratio. Weber number and Momentum ratio of air to liquid jet are shown to play important role in the atomization under varying mass flow rate of water and size of air nozzle respectively. Hence, these parameters are proposed as the correlating parameters for the first approximation of SMD under varying conditions of mass flow rate and the size of air nozzle. The use of convergent exit air nozzle is reported to reduce ‘drop sizes only for the case of large air nozzles, and does not prove to be advantageous in case of small air nozzles. The liquid post recess in the air nozzle cavity leads to increased drop sizes with the convergent exit and has little effect with the straight exit. The correlation with momentum ratio remains valid irrespective of the geometric variations.