ATOMIZATION CHARACTERISTICS OF IMPINGING LIQUID JETS

The atomization characteristics of sheets formed by both laminar and t urbulent impinging jets were experimentally studied as a function of n ow and injector geometric parameters. In particular, sheet breakup len gth along the sheet centerline, distance between adjacent waves appare nt on the sheet, and drop-size distributions were measured over a Webe r number range between 350-6600 and a Reynolds number range between 2. 8 x 10(3) to 2.6 x 10(4). A linear stability-based model was used to d etermine the most unstable wave number and the corresponding growth ra te factor on two-dimensional thinning inviscid and viscous sheets. The se wave characteristics were used to predict both the sheet breakup le ngth and the resulting drop sizes. A second model, applicable for a lo w Weber number regime, in which sheet disintegration is controlled by stationary antisymmetric waves, was used to predict the shape of the s heet formed by two impinging liquid jets. The linear stability-based t heory predictions of breakup length did not agree in trend or magnitud e with experimental measurements. However, for Weber numbers less than 350, the measured breakup length for laminar impinging jets was withi n 50% of that predicted by the stationary antisymmetric wave-based mod el. Finally, drop-size predictions based on linear stability theory ag reed in trend, but not in magnitude, with the measured drop sizes. The contrast between the sheet atomization characteristics of Laminar vs turbulent impinging jets suggest that the initial conditions of the im pinging jets significantly influence the sheet breakup mechanism. Also , the comparison between experimental results and theoretical predicti ons indicates that the impact wave generation process at the jet impin gement point needs to be incorporated in the theoretical models for sh eet atomization.