Wing Shape Improvement in the Presence of an Over-the-Wing Mounted UHBR Engine for a Short Range Transport Aircraft

Abstract

The aerodynamic benefit of over-the-wing mounted engines for commercial aircraft withSTOL capabilities in cruise flight conditions is explored. Favorable aerodynamic installation effects and less space constraints, like landing gear length for under-the-wing mounted engines, offer a promising potential for future transport aircraft configurations in combination with ultra-high bypass ratio engines. Nevertheless, the aerodynamic interaction between wing and engine, located at the wing upper side close to the trailing edge, is crucial and involves a design challenge to exploit the full aerodynamic performance potential. Especially the aerodynamics of the wing experiences a significant alteration due to the installation of the engine, which differs from engines mounted under a wing. The shock position and topology changes significantly and, consequently, also the spanwise load distribution is significantly changed. Therefore, the wing shape has to be adapted to the presence of the engine to meet the performance requirements and utilize potentially positive engine installation effects. Targeting on a low noise aircraft with short take-off and landing capabilities, two optimization steps were accomplished. As a first step, the wing-twist of a wing/body/engine/pylon (WBEP) configuration was adapted to improve the spanwise load distribution followed by a shape optimization. For this purpose, a surrogate-based optimization approach was applied.