2020 Fiscal Year Final Research Report

Study on Assumption of Upright Wall in the Theory of Added Resistance in Waves and on Application to Actual Ship

Research Project

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Project/Area Number	19K15222
Research Category	Grant-in-Aid for Early-Career Scientists
Allocation Type	Multi-year Fund
Review Section	Basic Section 24020:Marine engineering-related
Research Institution	National Institute of Maritime, Port and Aviation Technology
Principal Investigator	Sakurada Akiko 国立研究開発法人海上・港湾・航空技術研究所, その他部局等, 研究員 (00734237)
Project Period (FY)	2019-04-01 – 2021-03-31
Keywords	波浪中抵抗増加 / 船首部 / 反射波 / 喫水周波数影響係数 / ブラントネス係数
Outline of Final Research Achievements	The purpose of this study is verification and improvement of the estimation method of the added resistance in waves based on the theory assuming upright wall. In the first year, tank test was conducted on a blunt ship with the original bow and that with the bow concaved on the water surface. The results showed that the former is near the conventional method and the latter is smaller than that. That shows the effect of the bow. In the second year, a tank test was conducted using a simplified bow with the upright angle with the water surface, and a simplified bow with a small angle with the water surface. In the latter case, it was confirmed that the coefficient of draft and frequency using the latter model is small. As an improvement of the estimation method, the expression by the correction factor using representative angle between the side wall and the water surface was examined. It is verified that the expression is possible if it is applied to a simplified model ship.
Free Research Field	船舶海洋工学
Academic Significance and Societal Importance of the Research Achievements	本研究ではこれまで波浪中抵抗増加の理論計算法として実用化されてきたハイブリッド計算法におけるブラントネス係数と喫水周波数影響係数の直立壁仮定に注目した。ハイブリッド計算法では水槽試験により速度影響係数CUを求めるが、従来の船型では設計段階で評価できるように標準的な値が提案されている。一方で省エネ効果を期待して形状を工夫した船型では、標準的なCUよりも小さい値となる場合がある。このような船型に対して設計段階で評価する手法の検討は十分でない。本研究では水面と船側との代表角度により船型を表現し、波浪中抵抗増加との関係について考察した。この結果はさらなる省エネ船型の検討につながり社会的意義だと言える。