Development of partial coherence interferometry and its application to elucidation of thin liquid film behavior in pipe phase change heat transfer

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06109
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Thermal engineering
• Research Institution: The University of Tokyo
• Principal Investigator: Dang Chaobin 東京大学, 大学院新領域創成科学研究科, 准教授 (30401227)
• Research Collaborator: Yoshinaga yuki ; Yu Hanru
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 低コヒーレンス干渉法 / 薄液膜挙動 / レーザー干渉法

Outline of Final Research Achievements

Partial coherence laser interferometry is proposed as a new non-contact direct measurement method of the behavior of thin liquid film that governs the phase change characteristics of gas-liquid two-phase flow and phase change characteristics. Verification of the mechanism and the applicability to thin liquid film measurement was confirmed. The proposed method uses the phase discontinuity of the actual semiconductor laser to identify the relationship between the intensity of the interference fringes after passing through the thin film and the optical path length difference. Using this relationship, it is possible to extract not only the spatial distribution of the liquid film but also information on the absolute thickness of the liquid film. In addition, it was confirmed that non-contact measurement of liquid film behavior in high time and spatial resolution becomes possible by measurement using a high-speed camera.

Free Research Field

熱工学

Academic Significance and Societal Importance of the Research Achievements

細管における伝熱特性は，管内における冷媒の流動様式変化と壁面付近形成する液膜厚さおよびその乱れに密接な関係がある.その液膜の挙動の高時間，空間解像度での把握は極めて重要である．従来のレーザー共焦点変形計法は高精度，高時間的な解像度の計測が可能だが、空間的な分布をとらえることができない．レーザー干渉法用いた液膜の空間分布を精度良く検出手法が知られているが，液膜の絶対値の情報が直接得られないため，別の手法を併用するか，過熱領域から推算する必要がある．本提案手法は，簡易な半導体レーザーを用いて，高時間，空間解像度での液膜挙動の非接触計測が可能であるため，広い範囲での適用は期待される．