Study on Cavitation Flow in a Nozzle Hole and Its Effect on Spray Characteristics

喷嘴孔空化流及其对喷雾特性影响的研究

• 批准号: 09650242
• 负责人: NISHIDA Keiya
• 金额: $ 1.98万
• 依托单位: HIROSHIMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650242/
• 关键词: Spray; Liquid Atomization; Cavitation; Hole Nozzle

An experimental study was made to clarify the effects of cavitation bubbles' behavior in a nozzle hole on the breakup process of a liquid jet. Effects of superheat of the injection liquid, which promoted the onset of the cavitation bubbles in the nozzle hole, were also investigated. The liquid was injected continuously into the atmospheric air by the nozzle whose hole diameter was 0.5 nun. An ultrasonic transducer was attached to the nozzle to detect the acoustic intensity due to the onset, develop and collapse of the cavitation bubbles. Impedance of the liquid along the cross section of the nozzle hole was measured by a pair of thin electrodes which were installed in the nozzle hole wall from the outside. Breakup length of the liquid jet was measured by an electric resistance method. Microscopic observation was made of the breakup process of the liquid jet. Main results are summarized as follows.(1) The ultrasonic transducer detected the behaviors of the cavitation bubbles, such as the onset, develop and hydraulic flip.(2) The impedance of the liquid in the nozzle hole detected the attachment and the detachment of the liquid flow surface to the nozzle hole wall.(3) Waves on the liquid jet shows a very complicated structure when the injection pressure was a little lower than the hydraulic flip pressure.(4) Waves parallel to the nozzle hole axis were observed when the hydraulic flip occurred. These waves were supposedly related to the reattachment lines of the liquid flow in the nozzle hole.(5) Injection of the superheated liquid made the dispersion of the spray very large and the breakup length very small.(6) The effect of superheat on the spray characteristics is more dominant for the longer hole nozzle than the sorter hole one.

通过实验研究了喷嘴孔内空化气泡的行为对液体射流破碎过程的影响。还研究了喷射液体的润湿性对喷嘴孔中空化气泡产生的影响。通过孔径为0.5mm的喷嘴将液体连续地喷射到大气中。超声换能器连接到喷嘴，以检测由于空化气泡的开始、发展和破裂而引起的声强度。沿着喷孔横截面的液体沿着的阻抗通过从外部安装在喷孔壁中的一对薄电极来测量。用电阻法测量了液体射流的破碎长度。对液体射流的破碎过程进行了微观观察。主要结果总结如下。(1)超声换能器检测空化气泡的产生、发展和水力翻转等行为。(2)喷嘴孔中的液体的阻抗检测液体流动表面与喷嘴孔壁的附着和分离。(3)当喷射压力略低于液体翻转压力时，液体射流上的波呈现出非常复杂的结构。(4)当水力翻转发生时，观察到平行于喷嘴孔轴线的波。这些波被认为与喷嘴孔中液体流的再附着线有关。(5)过热液体的注入使得喷雾的分散度非常大，而破碎长度非常小。(6)长孔喷嘴的雾化特性受湍流度的影响比小孔喷嘴的大。

项目成果

金 壮憲: "直噴式ディーゼル機関用燃料噴射ノズル内の流れの特性とその噴霧挙動への影響 -針弁が上昇過程にある場合-" 自動車技術会論文集. 29・4. 29-34 (1998)

Jong-hyeon Kim：“直喷式柴油发动机喷油嘴中的流动特性及其对喷雾行为的影响 - 当针阀处于向上过程时 -” 日本汽车工程学会汇刊 29。・4.29-34（1998）

Tamaki,N.: "Effects of Cavitation and Internal Flow on Atomization of a Liquid Jet" Atomization and Sprays. Vol.8. 179-197 (1998)

Tamaki,N.：“空化和内部流动对液体射流雾化的影响”雾化和喷雾。

水口貴之: "噴射終了時における直噴ディーゼル機関用燃料噴射ノズルの内部流れと噴流の挙動 -10倍モデルノズルによる観測実験-" 第7回微粒化シンポジウム講演論文集. 203-208 (1998)

Takayuki Mizuguchi：“喷射结束时直喷柴油机燃油喷射喷嘴的内部流动和喷射行为 - 使用 10x 模型喷嘴的观察实验 -”第七届原子化研讨会论文集 203-208（1998）。

Mizuguchi, T.: "End-of-Injection Characteristics of D.I.Diesel Nozzle (Visual Study Using Ten-Times Model Nozzle)" Proceedings of the Japan Society of Mechanical Engineers. No.995-1. 249-250 (1999)

Mizuguchi, T.：“D.I.柴油喷嘴的喷射结束特性（使用十倍模型喷嘴的视觉研究）”日本机械工程师学会会议录。

Tamaki,N.: "Effects of the Internal Flow in a Nozzle Hole an the Breakup Processe of a Liguid Jat" Proceedings of ICLASS-'97. Vol,I. 417-424 (1997)

Tamaki,N.：“喷嘴孔内部流动的影响和液体 Jat 的破碎过程”ICLASS-97 论文集。