Innovation in next-generation small aircraft wings brought by fractal wings

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K18767
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 19:Fluid engineering, thermal engineering, and related fields
• Research Institution: Kyoto University (2023); Nagoya University (2022)
• Principal Investigator: Nagata Koji 京都大学, 工学研究科, 教授 (50274501)
• Co-Investigator(Kenkyū-buntansha): 渡邉 智昭 名古屋大学, 工学研究科, 准教授 (70772292)
• Project Period (FY): 2022-06-30 – 2024-03-31
• Keywords: 流体工学 / 空気力学 / 翼周り流れ / 風洞実験 / 数値解析

Outline of Final Research Achievements

This study investigates the aerodynamic characteristics of airfoils partially equipped with fractal structures (fractal airfoils) in the low-Reynolds-number regime. Wind tunnel experiments are conducted using symmetric and frat airfoils under steady and unsteady conditions. A total of six types of fractal wings with different porosity and fractal part positions (fractal part with porosity of 0.3 and 0.6 at the leading edge, fractal part with porosity of 0.3 and 0.6 at the trailing edge) are examined with measurements of the lift and drag forces and flow visualization using the smoke-wire method. The results show that the fractal structures significantly influence the flow characteristics around the airfoil and lift and drag forces, effectively reducing the occurrence of a dynamic stall in unsteady conditions. In addition, large eddy simulations are performed for airfoils with permeable or slit parts in order to elucidate the improvement of the performance of small airfoils.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

将来の火星探査手段として有望視されている「火星飛行機」や近年注目を集めている小型無人航空機においては従来の航空機に比べてレイノルズ数が1～2桁小さく、従来の設計思想に基づく翼を用いることができない。本研究はこのような低レイノルズ数域で航行する小型機翼に対して新たな提案を行うものである。学術的にも、透過構造による翼面上での流れのはく離制御と関連して流体力学分野に新たな知見を与えるものである。