NUMERICAL DESIGN AND ASSESSMENT OF A BIPLANE AS FUTURE SUPERSONIC TRANSPORT: REVISITING BUSEMANN'S BIPLANE

摘要

Aiming to realize a new concept supersonic transport, aerodynamic design and performance evaluation of biplane airfoils are discussed based on Computational Fluid Dynamics (CFD). In supersonic flight, airfoils generate strong sonic booms and wave drags accompanied by shock waves. To reduce them, Busemann's biplane concept is adopted and developed. A two-dimensional biplane configuration has been successfully designed using modern CFD simulation and a newly developed inverse problem. When the lift coefficient is more than 0.144, the designed biplane having a reasonable airfoil thickness gives lower wave drag than that of a flat plate. CFD assessment has also performed concerning the peculiar aerodynamic characteristics attributed to biplane configuration. They are hysteresis and choking phenomena which produce much amount of drag as an off-design condition. The promising strategy to avoid the drag increase is also demonstrated.