Development of Liquid Atomization lnduced by Laminar-Turbulent Transition of Free Liquid Film Flow and Elucidation of the Atomization Mechanism

自由液膜流层流-湍流转变诱导液体雾化的进展及雾化机理的阐明

• 批准号: 08650219
• 负责人: AZUMA Tsuneo
• 金额: $ 1.41万
• 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: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650219/
• 关键词: Laminar-turbulent transition; Llquid atomization; Liquid film flow; Radial flow; Boundary layr; lnstability; 自由液膜流; 安定性; 放射状流れ; 速度分布; 境界層

The disintegration of a radially thinning liquid sheet into drops, which is induced directly by the transition from laminar to turbulent flow, is investigated.The liquid sheet in the present experiment is generated as follows ; a radial liquid film flow is formed by a tap water issue from a thin cylindrical gap, which is constructed by the end of a circular pipe and the flat surface of a circular plate, to suppress the turbulence of the flow to the utmost. The liquid film flows radially outward on the plate, detaching from the peripheral edge of the plate, and then the liquid flows outward as a radially thinning liquid sheet in still air.Although the liquid aheet is laminar with a smooth liquid surface under the low Reynolds number flow, the transition of the thin liquid sheet begins to occur at a location of several millimeters downstream of the plate edge at high Reynolds number flow, being attributable to the velocity profile having an inflection point dueto the removal of the shear … More stress on the wall. The intensity of the turbulence increases with the Reynolds number, and the turbulence begins to sporadically perforate the liquid sheet at a immediately downstream location from the plate edge. A further increase in the number of perforation with the discharge Reynolds number causes to decreasing in sizes of webs and strands, and finally, the configuration of the web of strand does not appear in the liquid sheet and the transition results in the sudden breakup of the sheetinto drolets and clumps. The sizes of droplets are several tens micrometers and those of clumps are several hurdreds to some thousands micrometers.Although the quality of the disintegration rises further with the stagnant pressure, there are two limitations. The one is that the liquid film flow at the plate edge must have a fully developed velocity distribution, and the other is that no transition occurs in the flow on the plate. Flow conditions for the effective disintegration directly due to the transition of the liquid sheet are also clarified. Less

研究了径向变薄液膜的解体过程，液膜是由层流向湍动转变而产生的。实验中的液膜是由自来水从圆管末端和圆板的平面构成的细长圆柱形缝隙中喷出，形成径向液膜流动，以最大限度地抑制流动的湍流。液膜在平板上径向向外流动，与平板边缘分离，然后液体在静止空气中以径向变薄的液膜形式向外流动。尽管在低雷诺数流动下液膜是层流的，液面光滑，但在高雷诺数流动时，薄液膜在平板边缘下游几毫米处开始发生转变，这是由于剪切…的去除导致速度分布具有拐点。墙上的压力更大。湍流的强度随着雷诺数的增加而增加，并且在紧邻平板边缘的下游位置，湍流开始零星地穿透液膜。随着出流雷诺数的增加，穿孔数进一步增加，导致片状和片状尺寸减小，最终片状网状结构不再出现在液膜中，这种转变导致片状片状物突然碎裂成细小和块状。液滴大小几十微米，团块大小从几千微米到几千微米。尽管随着滞留压力的增加，崩解质量进一步提高，但存在两个局限性。一是平板边缘的液膜流动必须具有完全发达的速度分布，二是平板上的流动不发生转折。阐明了液膜转变直接产生有效解体的流动条件。较少

项目成果

T.AZUMA and T.WAKIMOTO: "Breakup and Drop Formation of a Radial Liquid Sheet Induced by Laminar-Turbulent Transition" Proc.3rd Int.Conf.on Multiphase Flow,ICMF′98. (to be published). (1998)

T.AZUMA 和 T.WAKIMOTO：“层流湍流转变引起的径向液体层的破裂和液滴形成”Proc.3rd Int.Conf.on Multiphase Flow，ICMF′98（待出版）。

Tsuneo AZUMA: "Instability and Transition in a Radial Boundary Layer Flow" JSME CENTENNIAL GRAND CONGRESS,Proc.Int.Conf.on Fluid Engineering,. 1. 339-344 (1997)

Tsuneo AZUMA：“径向边界层流中的不稳定性和过渡”JSME 百年大大会，Proc.Int.Conf.on 流体工程，。

脇本 達郎、東 恒雄: "放射状自由液膜流れの乱流遷移による液体微粒化に関する研究" 日本機械学会論文集(B編). 64(to be published). (1998)

Tatsuo Wakimoto、Tsuneo Higashi：“径向自由液膜流湍流转变引起的液体雾化研究”，日本机械工程师学会会刊（B 版）（1998 年）。

Tsuneo AZUMA and Tatsuro WAKIMOTO: "Breakup and Drop Formation of a Radial Liquid Sheet Induced by Laminar-Turbulent Transition" Proc.3rd Int.Conf.on Multiphase Flow, ICEF'98. (to bu published). (1998)

Tsuneo AZUMA 和 Tatsuro WAKIMOTO：“层流-湍流转变引起的径向液体层的破裂和液滴形成”Proc.3rd Int.Conf.on 多相流，ICEF98。

Tatsuro WAKIMOTO and Tsuneo AZUMA: "Liquid Atomization of a Radial Liquid Sheet Due to Transition to Turbulence" Trans.of Japan Soc.Mech.Engrs. (in Japanese). (to be published).

Tatsuro WAKIMOTO 和 Tsuneo AZUMA：“由于过渡到湍流而导致径向液体层的液体雾化” Trans.of Japan Soc.Mech.Engrs。