CHARACTERISTIC STUDY ON THE LIKE-DOUBLET IMPINGING JETS ATOMIZATION

Experimental studies on like-doublet impinging jets have been conducted by employing a photographic imaging technology and laser diffraction particle sizing device. The injector diameter is first carefully made as small as 0.3 mm, to determine its possible improvement in impinging atomization. Purified tap water is used as test liquid, and the velocity of impinging jets is approximately 50 m/s. Four spray patterns are found, which is somewhat different from the results of Heidmann [2]. Also, drop velocity distribution is bell shaped, and a newly defined shedding angle shows that drops are throw off tangentially from the sheet rim periphery. Shedding angle increases linearly with increasing position angle, with a sharp change near the axial axis, which reveals that drops shed may penetrate through the axial axis from one side to the other. Mean droplet size decreases sharply with increasing jet velocity in the low jet velocity regime, and flattens when the jet velocity increases sufficiently. For all angles of impingement, a unique mean drop size is found when the jet velocity is high enough. Comparison of data with those observed by Dombrowski and Hooper [5] shows an improvement in atomization which is attributed to the fact that the orifice size in this work is smaller than those used by previous authors.