The effect of complex flow in the stagnation-point region of counter Jets on material mxing with high Peclet number

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03850
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: University of Yamanashi
• Principal Investigator: TSUNODA Hiroyuki 山梨大学, 大学院総合研究部, 准教授 (10207433)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 乱流 / 噴流 / 対向噴流 / よどみ点 / 乱流界面 / パッシブスカラ / PLIF

Outline of Final Research Achievements

In the first year, several fluorescent dyes and optical filters with absorption wavelengths compatible with the newly purchased red laser and the existing pulse-emission green laser were selected, and the relationship between concentration and fluorescence intensity of selected dyes was investigated. Due to the failure of the green laser, the second year was limited to experimental preparation. In the final year of the project, interface detection experiments in a normal round jet were conducted for both laminar and turbulent flows. Different fluorescent dyes were mixed with the jet and ambient fluid, and the fluorescence from each dye was captured by a high-speed camera. Although the contrast of the fluorescence image was insufficient due to the low intensity of the substituted green laser, the interface of the laminar jet was successfully detected. For comparison, visualization experiments of annular jets were performed, and their results were presented in a scientific conference.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

スカラ場の濃度がゼロとなる境界で噴流の乱流域と非乱流域の界面を近似するという考え方は単純であり，過去に多く採用されている．しかし，ゼロへと漸近していく濃度場から濃度ゼロの境界線を取り出すことは困難であることから，実際にはしきい値が設けられ，それが曖昧さの要因となる．本研究手法では，噴流と周囲流体に発色が異なる二種類の蛍光染料を混入し，両染料からの蛍光画像を重ねることで，しきい値を設けなくとも両者の境界がより鮮明に得られることが期待できる．さらに，速度情報を同時取得する2色PLIF/PIV計測システムへの拡張も可能である．界面と速度場を同時計測した研究は世界的にも見当たらず，学術的意義は大きい．