Development of New Atomization Technique Based on Laminar-Turbulent Transition of Free Liquid Film Flow and Elucidation of Disintegration Mechanism

水从喷嘴通过喷嘴和圆盘之间的小间隙径向变化，形成液膜，其中即使在液体表面也形成层流边界层型速度分布，并且液膜径向流入空气。在这样形成的径向液膜中，当液膜较薄且放电雷诺数较大时，在层流-湍流转变之后立即产生大量穿孔，结果液膜被雾化。对相变发生点附近的详细观察表明，液膜的相变、穿孔和雾化是通过以下过程发生的：(1)出现波纹同心波(D波)，并通过D波的三维转换形成波状不规则结构：(2)在凸起部分集中形成(层流-湍流转变)细颗粒波(SL波)，通过颗粒波的集中形成波状液体聚集体。由于薄膜凹陷部分变薄而形成薄膜。(3)薄膜上的穿孔和穿孔的扩大。通过分离液体聚集体外围部分的微凸起形成尺寸为20-30 mm的液滴(微凸起分离型破碎)。(4)液体聚集体变形为单片状液体链，并通过液束破裂形成尺寸为300-500 mm的液滴(液体聚集体解体)。此外，我们还阐明了当由于高雷诺数或圆盘旋转而在圆盘上发生转变时，穿孔被高度抑制；我们还给出了由于微凸起分离型破碎而发生雾化的条件。

Water is radially dischanged from a nozzle through a small gap between the nozzle and a disk to form a liquid film in which laminar boundary layer type velocity distribution is developed even on the liquid surface, and the liquid film flows radially into the air. In the thus formed radial liquid sheet, a large number of perforations are generated immediately after the laminar-turbulent transition when the liquid film is thin and the discharge Reynolds number is large, and as a result, the liquid film is atomized. Detailed observation of the point near the occurrence of transition revealed that the transition, perforation and atomization of the liquid film occur by the following process.(1) Appearance of the rippled concentric waves (D waves) and formation of wavy irregularities by three-dimensional conversion of the D waves.(2) Concentrated formation (laminar-turbulent transition) of the fine-granular waves (SL waves) at the convex part and formation of the wavy liquid aggregates by concentration of the granular waves. Formation of thin membranes due to the thinning of the concave parts of the film.(3) Perforation at the membranes and expansion of the perforations. Formation of droplets of 20-30 mm in size by separation of the microprojections at the peripheral parts of the liquid aggregates (microprojection separation-type breakup).(4) Deformation of the liquid aggregates into monoliform liquid strands and formation of drops of 300-500 mm in size by the breaking of the liquid strands (liquid aggregate disintegration-type breakup).In addition, we clarified that when transition occurs on a disk due to a high discharge Reynolds number or disk rotation, perforation is highly suppressed ; we also showed conditions in which atomization occurs due to microprojection separation-type breakup.