Study on the friction drag reduction by electrolytic precipitation method

2017 Fiscal Year Final Research Report

• Project/Area Number: 16K18328
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Naval and maritime engineering
• Research Institution: National Institute of Maritime, Port and Aviation Technology
• Principal Investigator: Hiroi Takamichi 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 (60734233)
• Project Period (FY): 2016-04-01 – 2018-03-31
• Keywords: 摩擦抵抗低減 / マイクロバブル / 乱流 / 流体工学 / 船舶工学

Outline of Final Research Achievements

The purpose of this study is to clarify the mechanism of the change of turbulent flow by electrolytic precipitation method which generate small particles and bubbles, to develop the method of drag reduction by using this mechanism. Firstly, the size of the particle and bubble are investigated by Shadow Image Technique. The size of the bubble is under micron size. The bubble diameter is about 5 to 100μm. Secondly, the turbulent channel flow field with the particle and bubble is investigated by Laser Doppler Velocimetry and Particle Image Velocimery. It becomes clear that the bubbles are the main factor of the change of flow. The bubbles cause the reduction of Reynolds shear stress. It is confirmed that the turbulent component of friction drag decreases by 6.4% at despite a small void fraction of 2.84E-4 %.

Free Research Field

船舶海洋工学