Effective heat transfer enhancement and the application using dissimilarity effect of localized turbulence

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K14671
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: Tokyo University of Science
• Principal Investigator: Fukudome Koji 東京理科大学, 工学部機械工学科, 助教 (70710698)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: 強制対流 / 乱流 / 非相似性 / 乱流スポット

Outline of Final Research Achievements

Generally, when we increase the convective heat transfer, turbulent flow is one of the solutions. However, the turbulent flow is accompanied by an increase in fluid friction because of the similarity represented by Colburn's analogy, increasing power input. This study discovered a new characteristic flow that breaks the similarity and realizes an efficient heat transfer state by using direct numerical simulations. The objective flow is turbulent spots that develop in the laminar plane Couette flow. As a result, an efficient heat transport state was confirmed for the developing turbulent spot, and we revealed that the small-scale turbulent motion contributes appearance of the dissimilarity. Furthermore, it was found that similar efficient heat transfer states were confirmed in the growth process of the turbulent spots under thermal density stratification.

Free Research Field

熱工学

Academic Significance and Societal Importance of the Research Achievements

近年のエネルギー問題の解決にむけて熱交換器の効率を向上させることは喫緊の課題である．しかし，流体の熱輸送と運動量輸送の相似性から，熱輸送のみを増加させることは一般に困難であった．本研究で発見した乱流スポットの効率的熱輸送状態は，これからの非相似性を有する流れの実現に向けて重要な礎となることが期待できることから学術的意義が大きいと考えられる．さらに，熱交換器や物質混合器などの性能向上を実現し，様々な設計問題のブレイクスルーに繋がることから工学的意義が大きい．また，エネルギーの有効利用に貢献し，社会的な環境問題や資源問題の解決の一助となることが期待できる．