Experimental Study On Characteristics Of Fluid Dynamic Ultrasonic Atomizer

The application situation and problems of oil atomizer were analyzed in this paper. Based on the analysis, the principles and characteristics of fluid dynamic ultrasonic atomizer were introduced, and a set of ultrasonic atomizers were designed. Then spray and burning experiments of the ultrasonic atomizers were conducted. Through spray experiments, the influence of pressure of compressed air, water pressure and air-liquid-rate(ALR) on atomization diameter and atomization angle was analyzed. Further more, the characteristic of the granularity distribution along the nuzzle axis was studied. The experiments showed that: the fluid dynamic ultrasonic atomizer had a well atomization effect on both water and oil, and the Sauter Mean Diameter(SMD) of the atomizers were about 10~20μm; with the increase of pressure of compressed air, both the atomization diameter and atomization angle decreased, and the higher of the air pressure the less of the trend of decrease; with the decrease of pressure of water, both the atomization diameter and atomization angle increased, and the higher of the water pressure the less of the trend of increase; both atomization diameter and atomization angle decreased with the ALR increasing, but when ALR increases to a certain number, both of them would have little change, and this ALR regards as the best one; with the increase of the distance between the test point and ultrasonic nuzzle, the atomization diameter increased, and the larger distance the less of the trend of increase.Based on the spraying experiments, a contrast experiment of characteristics between fluid dynamic ultrasonic atomizer and traditional external mixing air blast atomizer was designed. It was found that: the atomization diameter of ultrasonic atomizer was obviously lower then traditional atomizer, and ultrasonic atomizer had a much bigger adjust ratio; with the increase of the distance between test point and ultrasonic nuzzle, the atomization diameter of ultrasonic atomizer increased, while the atomization diameter of traditional atomizer decreased first and then increased; the atomization angle and atomization length of both the ultrasonic atomizer and the traditional atomizer had the similar changes with the change of air pressure and water pressure, the different was that the ultrasonic atomizer had a bigger atomization angle and a shorter atomization length.In addition to the spraying experiments, a burning experiment of the ultrasonic atomizer proceeded. The burning experiment showed that: the fluid dynamic ultrasonic atomizer had a so well atomization effect on 250# heavy oil that it could be burn at 70~80℃in cold furnace, and the heavy oil could burning steadily with an air pressure of 0.4MPa; during the burning experiment, the concentration of NOx and SO2 were high in the smoke, and this situation should be avoid in the design of ultrasonic atomizer for the future.Through spray and burning experiments, the paper summarized characteristics of fluid dynamic ultrasonic atomizer, analyzed the advantage and disadvantage of the ultrasonic atomizer, and put up advices for the design of ultrasonic atomizer.