权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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

基于自由液膜流层流-湍流转变的新型雾化技术的开发及崩解机理的阐明

基本信息

批准号：
10650185
负责人：
AZUMA Tsuneo
金额：
$ 2.18万
依托单位：
Osaka City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650185/
关键词：
Laminar-Turbulent Transition Atomization Liquid Film Flow Instability Droplet Boundary Layer 境界層

项目摘要

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.

水通过喷嘴和圆盘之间的小间隙从喷嘴径向排出，形成液膜，其中即使在液体表面上也形成层流边界层型速度分布，并且液膜径向流入空气中。在由此形成的径向液体片中，当液膜薄且排出雷诺数大时，在层流-湍流转变之后立即产生大量穿孔，结果，液膜被雾化。对转变发生点附近的详细观察表明，液膜的转变、穿孔和雾化是通过以下过程发生的。（1）出现波纹状同心波（D波），并通过D波的三维转换形成波状不规则性。（2）在凸部和细粒波（SL波）集中形成（层流-湍流转变）。通过颗粒波的集中形成波状液体聚集体。由于膜的凹部变薄而形成薄膜。(3)膜上的穿孔以及穿孔的扩大。通过液体聚集体周边部分的微突出物的分离，形成尺寸为20-30mm的液滴(微突出物分离型破碎)。 (4)液体聚集体变形为单条液体线，并通过液体线的破碎形成尺寸为300-500mm的液滴(液体聚集体崩解型破碎)。我们澄清，当由于高放电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；我们还展示了由于微突出分离型破碎而发生雾化的条件。