Small Aspect Ratio High Efficiency Aerodynamic Layout

The history of the aerodynamic configuration of airplane was reviewed, in order to improve the aerodynamic efficiency of the low aspect ratio aircraft. Tow methods were promoted according to the aerodynamic characteristics of the low aspect ratio aircraft. First, for the induced drag reduction, the distribution of the aerodynamic load along the span was designed to be closed to elliptic by the panel method. Second, for the viscous drag reduction, the blended wing lifting fuselage was designed and was analyzed by the computational aerodynamics. For the sake of verifying the high efficiency of the blended wing lifting fuselage, the conventional wing-body configuration, that is a wing with a columned fuselage, and the non-blended wing lifting fuselage were compared with it. The conclusion was that the blended wing lifting fuselage had highest aerodynamic efficiency. At the end of the dissertation the winglet was analyzed as the effective means to reduce the induced drag and to make the configuration more efficient.Focusing on the above research work, six parts were investigated: 1,The bottle-neck factors of the aerodynamic efficiency improvements of the conventional wing-body configuration, which was designed according to Cayley principle, were analyzed. The factors were conventional fuselage and aerodynamic load distribution along the span. The all lifting aircraft concepts were reviewed in the history. The difficulties of the low aspect ratio wing design were concluded basing on the experimental research papers analysis. It was founded that the blended wing lifting fuselage configuration could be used as effective concept to reduce the induced drag and the viscous drag by means the span lift distribution design and the wetted surface area reduction.2,The state of arts of the computational aerodynamics was reviewed on the viewpoint of the applied aerodynamics. The way to use the computational aerodynamic was obtained basing on the analysis of the three drag prediction workshop of AIAA and the author's experience on the design method of supersonic drag reduction.3, The computational methods used in the dissertation were presented and were verified through airfoil, wing and wing-body computations. The results showed that the methods had enough ability to analyze the aerodynamic force difference among the configurations. The drag decomposition method showed good...