遷音速流れ場の相似則と二次元複葉翼の数値解析結果への適用

摘要

General transonic similarity rules and the similarity rules around Mach 1 on the aerodynamic coefficients of quasi-cylindrical bodies including biplanes are developed to extract the characteristic dimensionless quantities for flow-fields around transonic biplanes. To verify the similarity rules, numerical simulations of biplane airfoils are performed by solving the Euler equations. Two RAE2822 airfoils are used in the simulations as typical transonic airfoils. The results of the numerical simulations show good agreement with the similarity rules even if there is shock wave interaction between the wings. Furthermore, shock wave patterns are the same when the values of similarity parameters are the same. These results illustrates the potential of the similarity rules for searching wide range of design space and classifying the shock wave patterns. Applying similarity rules to biplane airfoils in transonic flows, the relationship between the distance of the wings in the uniform flow direction and aerodynamic coefficients are numerically investigated. The result show that the lift-to-drag ratio is large when the upper wing is placed upstream of the lower wing.%1.1 研究背景今日，航空機燃料価格の上昇に加え，航空輸送量の増加とともに環境への影響が増大していること から，航空機の燃費や排気ガスの低減に強い開心が向けら れている.そのため，片持ちの主翼形態をした従来の航空 機とは異なる新しい形態を採用することで性能の向上を図 る試みが欧米を中心になされている.その中の1つとして 遷音速飛行する複葉翼機が提案されている. 複葉翼機の 利点は，下翼で上翼を支持することにより構造重量の増加 を抑えたまま上翼アスペクト比を大きくでき，従来機より 誘導抵抗を減少させ燃費が低減される点である.