A Study on Turbulent Friction Drag Reduction Method Using Acoustic Flow Radiation by Surface Acoustic Wave

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K18914
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 24:Aerospace engineering, marine and maritime engineering, and related fields
• Research Institution: National Institute of Maritime, Port and Aviation Technology
• Principal Investigator: KAWASHIMA HIDEKI 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 (20450679)
• Project Period (FY): 2018-06-29 – 2020-03-31
• Keywords: 弾性表面波 / 音響流 / 流場制御 / 抵抗低減

Outline of Final Research Achievements

In order to radiate the acoustic flow from the flow field control device at an appropriate angle, a method of stacking piezoelectric materials with metal or plastic materials was developed and the change of longitudinal wave propagation speed was studied depending on the combination of materials.
Then, prototype flow field control devices were fabricated, and resonant frequency measurement tests were carried out, and it was confirmed that the longitudinal wave propagation speed could be varied.
The method to estimate the longitudinal wave propagation velocity of composite piezoelectric materials has been developed to design flow field control devices.

Free Research Field

流体力学

Academic Significance and Societal Importance of the Research Achievements

船舶の場合、全抵抗の70～80％を乱流摩擦抵抗が占めるため、温室効果ガスの排出を削減するには、乱流摩擦抵抗を低減する方法の開発が重要である。現状では、船舶の乱流摩擦抵抗を削減する実用化された手段は、研究代表者もその実現に貢献した空気潤滑法のみである。本研究では、物体表面に圧電素材と櫛歯回路により、弾性表面波を発生させ、物体壁面の接線方向に近い角度の音響流を放射し乱流境界層内の流体を直接制御することで、乱流摩擦抵抗低減を図る音響流放射型流場制御デバイスの研究を行い、音響流の放射角を決定する因子である圧電素材の縦波の伝搬速度を制御する手法を開発できたことに、学術的、社会的意義がある。