Integration of Wing-Mounted Over-Wing Engines on a Mid-Range Aircraft

Abstract

Ultra-High Bypass Ratio (UHBR) engines are an important technology for improving the efficiency of future aircraft. However, their large diameter poses a major challenge for their use in conventional under-wing mounted engine configurations due to limited space. A configuration with engines mounted above the wing is not subject to these limitations and therefore offers the potential for improvements in overall aircraft efficiency and performance. Another advantage of this configuration is the acoustic shielding effect of the fan noise toward the ground by the wing. Configurations with this type of engine layout were investigated as part of the German LuFo V project AVACON (AdVanced Aircraft CONcepts). This paper describes the investigated variant of engine integration via a vertical pylon between nacelle lower side and main spar of the wing. To investigate the complex aerodynamic interactions between the engine and the wing, RANS CFD simulations were performed using the DLR code TAU. By optimizing twist and upper surface shape, the wing geometry was adapted to the flow conditions resulting from the engine integration to reduce detrimental aerodynamic installation effects. In general, the influence of the geometric shape of the wing and engine as well as their relative geometric position on the overall drag is more pronounced in such a configuration than in a under-wing engine design. The use of advanced optimization methods is therefore crucial for a successful design.