高周波脈動流中の気液界面から飛散分裂する液滴群の挙動の統計評価とモデリング

高频脉动流中从气液界面散射和破碎的液滴行为的统计评估和建模

• 批准号: 21K03858
• 负责人: 尾形 陽一
• 金额: $ 2.5万
• 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: 2021
• 资助国家: 日本
• 起止时间: 2021-04-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-21K03858/
• 关键词: 気液二相流; 流体不安定性; 微粒化; モデリング; 脈動流; エンジン

今年度の研究計画である実機エンジン条件を模擬した，直管と曲り管内の変動気流場における評価，および飛散・分裂の数値モデルの構築とシミュレーションへの応用を行うため，風洞を用いて矩形断面直管内気流変動と壁面近傍の乱流強度計測，および前年度に実施した矩形断面直管内の定常・脈動気流中を流れる薄液膜から生じる飛散液滴の分裂機構・飛散発生条件を基に，曲管を流れる液膜からの液滴飛散・分裂挙動計測を行い，曲り部の気相分布との相関性を調査した．矩形直管では分裂発生の閾値気相流速を超えると，液膜から空間分布に偏り無く管内で飛散が発生するが，曲管では気相が曲り部に流入直後，局所的に気相が加速される領域で振幅の大きい波も生成され，直管で飛散が生じない流入速度でも高頻度で飛散・分裂が生じる．一方，曲り内側の気相剥離領域および曲り外側では直管の閾値速度より減速される領域が現れ，飛散も生じないことから，気相分布と飛散領域の相関が明らかとなり，流速に空間分布が有る場合も直管の飛散条件が局所的に適用可能であることが分かった．しかし，直管では生じない壁面からの反射波，波同士の干渉の効果も現れ，管の大きい曲り角では顕著になることから，曲り角もしくは曲率半径の組込みが必要と考えられる．また，多数の飛散計測から飛散サイズと分裂時間の統計評価を行い，単一液滴分裂と直管・曲管での液膜飛散分裂の類似・相異を調査した．気相流速の増加に伴い分裂時間は短くなり，単一液滴の流体力学的時間スケールの傾向と整合する一方，分裂が生じる臨界ウェーバー数は液膜の方が大きく，分裂時間は曲り部で直管より短くなる傾向も得られ，基礎データとしてモデル構築に応用出来る．

This year's research plan is to simulate the conditions of the actual machine, evaluate the dynamic potential flow in the straight pipe and the curved pipe, and measure the turbulence intensity near the dynamic wall surface in the straight pipe with rectangular cross section. In the past year, the steady and pulsating flow in a rectangular cross-section straight pipe was investigated. The thin liquid film was separated from the droplet by the mechanism of droplet separation. The conditions of droplet separation were based on the flow in a curved pipe. The phase distribution and correlation of the curved part were investigated. In rectangular straight pipes, the threshold phase velocity of splitting generation is exceeded, the liquid film is distributed in space, there is no scattering generation in the pipe, and in curved pipes, the phase is accelerated in the straight pipe, the amplitude of the wave is large, and the scattering generation in straight pipes is high. In one direction, the inner side of the curve has a phase separation field. The outer side of the curve has a threshold velocity of the straight pipe. The deceleration field is present. The dispersion field is generated. The phase distribution and the correlation of the dispersion field are bright. The spatial distribution of the velocity is available. The dispersion condition of the straight pipe is applicable. The reflection wave from the wall surface of the straight pipe is generated, and the reflection wave from the wall surface of the straight pipe is generated. The reflection wave from the wall surface of the straight pipe is generated. The reflection wave from the wall surface of the straight pipe is generated. The reflection wave from the wall surface of the straight pipe is generated. The reflection wave from the wall surface of the straight pipe is generated. In addition, statistical evaluation of dispersion time and dispersion measurement of most liquid droplets was conducted to investigate the similarity and difference of liquid film dispersion and dispersion of single liquid droplet and straight and curved tubes. The increase of gas phase velocity is accompanied by short splitting time, the hydrodynamic time of a single droplet, the tendency of integration, the critical number of liquid films, the large splitting time, the short splitting time, and the use of basic liquid structures.

项目成果

矩形管内の定常・脈動気流を受ける液膜飛散分裂挙動の研究

矩形管内稳态和脉动气流下液膜散射和破碎行为研究

• 发表时间: 2022
• 作者: 丸岡 朋貴;謝哲也;西田 恵哉;川口 幹祐;長野 祥江;幸徳 正信;中島聖;尾形 陽一
• 通讯作者: 尾形 陽一

水平矩形管の曲がりが気液界面の飛散・分裂に及ぼす影響

水平矩形管弯曲对气液界面散射和破碎的影响

• 发表时间: 2022
• 作者: Tomoki MARUOKA;Mikimasa KAWAGUCHI;Nishida KEIYA;Yoichi OGATA;Yoshie NAGANO;Akira NAKASHIMA ,Jun NISHIKAWA
• 通讯作者: Akira NAKASHIMA ,Jun NISHIKAWA

自動車エンジン排気系流動場を想定した脈動気流における 矩形管壁面熱伝達の研究

假设汽车发动机排气系统流场的脉动气流中矩形管壁的传热研究

• 发表时间: 2022
• 作者: Kemmei FUJIMOTO;Yuki KATO;Mikimasa K AWAGUCHI;Keiya NISHIDA;Jun NISHIKAWA;Hitoshi HONGOU;Kazuhiro NAKAMURA;Shinji SUMI;Yoichi OGATA
• 通讯作者: Yoichi OGATA