Effects of orifice size and impinging angle on the characteristics of a like-doublet impinging-jet

Observations and measurements on the spray pattern and size of the like-doublet impinging jets have been conducted in this work by employing photographic imaging technology and laser diffraction particle sizing device. The injector diameter is made skillfully to the size as small as 0.3 mm to investigate its possible improvement in impinging atomization. Purified tap water is used as test liquid, and velocity of impinging jets is up to approximately 50 m/s. Results show that four spray patterns found in this work are somewhat different from those of Heidmann /2/. Velocity distribution of the shedding drops is also presented as bell shape, and a new defined shedding angle is shown that drops are shed out tangentially from the sheet rim periphery. Shedding angle increases linearly with increasing position angle with a sharp change near symmetric axis which reveals that shed drops may penetrate through the symmetric axis from one side into the other. The mean droplet size monotonously decreases with jet velocity for all angles of impingement, and an asymptotic mean drop size is approached in high jets velocity. Comparison with those data observed by Dombrowski and Hooper /5/ shows that an improvement of atomization which is attributed to the orifice size in this work is smaller than that used by previous authors.