青山 剛史

極めて複雑なシステムとなっている近年の航空機は，その開発において，設計変更による手戻りや認証試験の複雑化などに起因する開発スケジュールの長期化およびコストの増大が大きな問題となっている．その解決手段として，デジタル技術，特にDX技術が世界的に注目されている．もし我が国がこの潮流に乗り遅れると，海外OEMのTier 1事業において確立してきた不可欠なパートナーとしての地位を失いかねない．このような状況下，JAXAは「新たな航空機を創出する航空機ライフサイクルDX技術の研究開発」を航空技術部門の活動における三本柱の一つと位置づけ，2022年度から着手している．その後，2023年度には，「経済安全保障重要技術育成プログラム」の一環として公募されたNEDO事業に，「航空機の設計，認証，生産プロセスの革新とプロセス統合」のテーマが採択され，共同提案者とともに設計DX，認証DX，生産DXおよびプロセス統合（DXプラットフォーム）の課題に取り組んでいる．

We simulate unsteady flows over a 30P30N slat by taking account of velocity fluctuations inside the turbulent boundary layer (TBL) on the slat. Embedded Large Eddy Simulation method is employed to generate pseudo turbulences inside the TBL. Also, we conduct additional simulation by Delayed Detached Eddy Simulation (DDES), which has been made without the pseudo turbulence, for making comparisons with the ELES case. Comparisons between the ELES and DDES results suggests that the pseudo turbulence makes the vortex structures of a shear layer extending from the cusp more three-dimensionally. The difference of vortex structure leads to the shear layer in the ELES case curves with a smaller radius of curvature. The time-averaged flow field of the ELES case is closer to the experimental result than those in the DDES case. While the shear layer on the cusp side is affected by the pseudo turbulence, there is no significant difference between the ELES and DDES cases in the shear layer extending from the TE of the slat.

The Japan Aerospace Exploration Agency (JAXA) and The Korea Aerospace Research Institute (KARI) jointly started activities related to the research and development of "Active Tab," a helicopter noise reduction technique. KARI constructed the analytical methodology consisting of the aerodynamic, structural dynamic and acoustic codes for defining the requirements to be used in evaluating the performance of Active Tab when installed in a Mach scaled assumed blade. Based on the requirements defined, JAXA carried out a conceptual design study, developed the Active Tab drive mechanism and evaluated its performance. The analytical results show Active Tab satisfying the requirements has sufficient noise reduction capability. Evaluation for the Active Tab drive mechanism demonstrated the dynamic performance and durability required practical use installed in helicopter blades.