Pylon Design for a Short Range Transport Aircraft with Over-the-Wing Mounted UHBR Engines

Abstract

Over-the-wing mounted (OWM) engines, together with their design challenges and their potential in terms of aerodynamic benefits and positive installation effects, are investigated with CFD methods. The analysed reference configuration is a new concept of a civil transport aircraft with short takeoff and landing characteristics featuring a circulation control supported high lift system. The concept is intended to provide extraordinary airfield performance while meeting low noise standards. The reference aircraft will be firstly analysed in its wing/body layout. Successively, engine and pylon will be integrated and analysed. A description of the pylon design and parametrization will be given. The results of the wing/body/engine/pylon configuration computations will be discussed in order to assess the transonic flow phenomena taking place on the upper wing when an engine is integrated over the wing in cruise condition and the overall impact of the pylon on the flowfield. Particular attention will be reserved to the flow on the pylon, in order to identify aerodynamic characterisitscs, possible flow separations and to evaluate a strategy for an optimization process. The pylon optimization procedure will be described in detail, together with the tools used and the parameters defining the pylon shape. The preliminary results and trends of the Design of Experiment will eventually be discussed in order to provide an outlook on complete optimization scenarios for such configurations.

A Review of Novel and Non-Conventional Propulsion Integrations for Next-Generation Aircraft

“…Initial qualitative comparisons seem to indicate an aerodynamic benefit for the top-fuselage installation, but the pylon design could involve a number of multidisciplinary interplays, mainly from a structural point of view, which require more detailed studies. A specific discussion on an overwing pylon design process is reported in [84], where some design variables and constraints related to the overwing pylon design are generally addressed, providing a frame for further development. The problem of the strict coupling in the design of the wing and the propulsive unit for an overwing assembly of a UHBR turbofan is discussed in more detail in [85].…”

Evaluation of ultra-high bypass ratio engines for an over-wing aircraft configuration

“…From the comparison of the drag areas containing friction, viscous pressure and wave drag, multipliers were derived, with which the calculated PrADO drag areas of wing, nacelles and pylons are corrected. Meanwhile, high-fidelity RANS results (TAU code of the DLR in Braunschweig, (Savoni and Rudnik, 2018)) for the UHBR aircraft are available in the CRC 880. They show a high agreement by the aircraft coefficients and confirm the simple correction approach for design applications.…”

“…The consequences are a doubling of the wetted surface and relatively high thickness ratios of the cross-sections (about 13.5%) compared to an under-wing pylon. The studies by Savoni and Rudnik (2018) show that the unconventional pylon geometry, with its influences on the shock system of the wing, determines approx. 15% of the aircraft drag and reduces the benefits from the installation drag significantly.…”