Development of novel assessment method for the safety of Arctic sea route for decreasing sea ice condition

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06968
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Naval and maritime engineering
• Research Institution: Kogakuin University
• Principal Investigator: Konno Akihisa 工学院大学, 工学部, 教授 (60322070)
• Co-Investigator(Kenkyū-buntansha): 北澤 大輔 東京大学, 生産技術研究所, 教授 (30345128)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 氷荷重 / 耐氷船 / 衝突 / 流体力 / 氷山片 / 氷塊

Outline of Final Research Achievements

This research aims at the proposal of the navigation safety assessment method which assumed the collision of a ship with an independent ice piece (such as a bergy bit) in the Arctic Sea Route in summer. This is realized by investigation of the time history of the kinetic energy of the ice piece before and after the collision with model tests and by building a numerical analysis method.
When the model ship and an artificial ice piece were made to collide in a model basin, the kinetic energy of the translational motion dominated the total energy and the rotation energy was negligible. In the case of the cubic ice piece, the rotational energy increases immediately after the collision but decreases promptly after that with that of the cylindrical ice.
By combining the numerical analysis of the collision and an estimation method of the ice load from consumed energy, the safe navigation velocities in the potential collision with an ice piece were evaluated under limited conditions.

Free Research Field

船舶海洋工学

Academic Significance and Societal Importance of the Research Achievements

氷海航行時の安全性評価の歴史は長いが、歴史的な経緯から結氷した海で砕氷船が平坦氷を割り進むような氷の多い状況を想定した研究が多く、極海コードの安全性評価もこれに基づいている。近年急速に進んだ海氷減少に対応しているとは言い難く、特に夏期の氷が少ない海域の航行は想定していない。本研究は目視や船舶レーダーでの発見が困難な氷山片と船舶との衝突を視野に、この状況の現象解明を試みており、北極航路の現状に一石を投じるものである。また船舶と氷塊との衝突時に並進運動成分が卓越することは報告例が乏しく、回転の減衰を数値解析に取り入れる手法が議論となっていたので、この意味でも意義がある。