Study on rheology of non-Newtonian two-phase flows through singularities in microchannels

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K04172
• 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: Kumamoto University
• Principal Investigator: Kawahara Akimaro 熊本大学, 大学院先端科学研究部(工), 教授 (20224818)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 混相流 / マイクロチャンネル / 気液二相流 / 非ニュートン流体 / 急縮小 / 急拡大

Outline of Final Research Achievements

For designing micro-size devices using gas and liquid as working fluids, the effect of singularity existing in the microchannel (its hydraulic equivalent diameter of 1 mm or less) on the flow characteristics of the two-phase flow of gas and non-Newtonian liquid was investigated. As a singularity, we adopted the sudden contraction and sudden expansion seen in piping systems such as micro reactors. In addition, several types of polymer aqueous solutions were used as non-Newtonian fluids. Then, the pressure change of the liquid single-phase flow and the two-phase flow passing through the singularity, and the change of the flow pattern of the gas and liquid due to the existence of the singularity were experimentally investigated. Based on the experimental results, a correlation was constructed to evaluate the pressure change when passing through a singularity. At that time, it was clarified that it is necessary to consider the viscoelastic properties of non-Newtonian fluids.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

マイクロメートルの代表径を有する流路内に存在する各種の特異点（急拡大・縮小等）を通過する非ニュートン流体は、マイクロ化学反応器、生体内の血液流れ等に見られる。非ニュートン流体の流体レオロジー特性は流れのせん断速度によって複雑に変化する。そして、流路寸法が小さくなるにつれてせん断速度が大きくなり、非ニュートン性が顕著に表れると予想される。したがって、効率の良いマイクロ反応器の設計・開発、心血管・循環器系の検査法や医療機器の開発では、高せん断場に存在する特異点が非ニュートン流体レオロジー特性に及ぼす影響を把握することが必要となるが、本研究を通してその一部を明らかにすることができた。