Development of prediction method for two-phase flow under ship bottom considering hydrodynamic characteristics on shell surface

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02365
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 24020:Marine engineering-related
• Research Institution: Tokyo University of Marine Science and Technology
• Principal Investigator: Hazuku Tatsuya 東京海洋大学, 学術研究院, 教授 (60334554)
• Co-Investigator(Kenkyū-buntansha): 井原 智則 東京海洋大学, 学術研究院, 助教 (70767350)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 空気潤滑法 / 気液二相流 / 抵抗低減

Outline of Final Research Achievements

From the viewpoint of advancing the air-lubrication method, a technique for reducing ship drag by supplying air to the ship's bottom, the final target of this study was to develop a two-phase flow analysis method that can reproduce the effects of wall surface characteristics on the two-phase flow structure and wall friction characteristics beneath a ship's bottom. Two-phase flow experiments with varying wall surface roughness were conducted using an apparatus that simulates two-phase flow beneath a ship's bottom. An experimental database on velocity distribution in the boundary layer, local two-phase flow structures, and frictional resistance before and after bubble supply was newly constructed. Based on the obtained database, the impact factors, including gas-liquid flow rate and channel wall roughness, were evaluated on the two-phase flow structure and constitutive equations regarding the two-phase flow structure and frictional resistance.

Free Research Field

船舶工学

Academic Significance and Societal Importance of the Research Achievements

固体壁面特性と気液二相流の流動構造及び摩擦抵抗の流体力学的相関に着目した研究は、国内外において類例がほとんどなく、その実験的、解析的研究を実施した本研究は、現状に鑑みて学術的意義が大きい。本研究により、特に二相流動構造と摩擦抵抗に及ぼす流路壁面粗さの影響に関する新たな知見が得られ、さらに船底下の二相流動構造と摩擦抵抗特性に関する二相流構成式が新たに開発された。これらの成果は、船底下に形成する二相流の解析技術を進展させるものであり、今後のさらなる研究の推進によって、空気潤滑法による船体抵抗低減技術の高度化が期待できる。