Theoretical study on the aerodynamic effect of mutual interaction in multi-body problems

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(1) A high performance aerodynamic device which utilizes supersonic multi element aerodynamics has been proposed. Biplane wings have been researched using computational fluid dynamics (CFD). Those wings realize almost drag-less performance by utilizing favorable interaction between pressure waves of two wing elements. Through the research in 2005 and 2006 years, one of the best biplane airfoil was designed. It has sufficient lift for the cruise with the speed of Mach 1.7 and the lift-drag ratio (l/d) is 21. This is the first time in the world to show that a lifted biplane can have such a high l/d performance. In 2007, biplane wings has been investigated by extending the designed airfoil to a three dimensional device. It has been also confirmed that an airfoil/wing design system, which has been developed in this project, works efficiently and accurately for the both of 2D and 3D design problems.(2) Detailed CFD analysis about multi body problems in a subsonic flow-field has been conducted A flow-field around aircraft has been simulated at the Mach number of 0.2. The configuration consists of a fuselage, an engine nacelle and a wing which has a slat and a flap in extended condition. Basic flow equations are Reynolds averaged Navier-Stokes ones. There occur many interactions between a slat and a main-wing, a wing and a nacelle etc. Therefore, the flow phenomena must be complicated. we intended to obtain useful data to model aerodynamic interaction. The computations have been conducted using grid distribution as high density as possible. At the present, qualitatively we have obtained reliable data. However, for the detailed analysis, the current resolution level is not sufficient. It is needed to devise advanced numerical techniques to analyze separated flow-fields, vortices and free sheer layers.