Parametric modelling of a long range aircraft under consideration of engine wing integration

Kurzfassung

In the recent past, an obvious trend of new aircraft developments to serve the desired high efficient aircraft has been noticeably: Since the overall configuration of the transport aircraft is well sophisticated, it has not changed over the last decades. To keep the development cost of the aircraft manufacturer low, existing aircraft configurations were nearly retained unchanged, but receive a new higher by-pass-ratio engine to reduce its fuel burn. This trend could be seen at the Airbus A320neo or the Boing 737 Max 8. Due to the higher by-pass-ratio, the diameter of the engine increases, but the space under the wing stays the same. One possible way to get the larger engine mounted under the wing is to increase the length of the landing gear. But if the wing and the fuselage topology of the aircraft should stay the same, the larger landing gear could not be retracted. The only way to mount a bigger engine under the wing and keep the requested ground clearance and the fixed wing-fuselage attachment is to shift the engine ahead of the wing, to be able to shift it upwards simultaneously. As reference configuration a generic long range wide body transport aircraft, the so-called D250 is used. The purpose of this paper is to show the influence of the modified engine position together with the higher engine mass on the aeroelastic characteristics of the aircraft compared to the baseline variant. The structural models for these analyses are set up using the automated aeroelastic structural optimization process called cpacs-MONA. First of all the cpacs-MONA process with its capabilities will be shown. This process consists of a parametric model set-up, an extensive loads analysis and a structural optimization. The loads analysis and the structural optimization are iteratively coupled until the mass and the loads of the aircraft configuration are converged. Afterwards the influence of the different engine wing integrations on the flutter characteristics of the optimized structure will be presented. The top-level aircraft requirements of the D250 reference configuration are connected to those of the long range aircraft A330-200. The span of the D250 is about 58 meters, its aspect ratio is 9.3 and its maximum take-off mass is 230 metric tons. The outer diameter was increased by one meter and the mass per engine by 500 kilograms. The position of the engines center of gravity (CG) was shifted one meter to the front and a half meter upwards, in order to keep the same ground clearance between the two variations. cpacs-MONA is a parameterized design process for the structural and aeroelastic design of aircraft configurations. For this trade-off study it will be used as stand-alone tool. cpacs-MONA can also be part of extensive multidisciplinary and high fidelity-based design tasks as a sub-process, where for example further disciplines like aerodynamics or overall aircraft design are involved. The name MONA refers to the main computer programs involved, ModGen and MSC Nastran. ModGen is a DLR in-house computer program to set up the structural and aerodynamic models for the loads analysis and the structural optimization. MSC Nastran is used to perform these analyses. The so-called Common Parametric Aircraft Configuration Schema (CPACS) is a DLR development to define almost all aircraft parameters like geometry, structure, material, masses, etc. in a suitable dataset. cpacs-MONA is controlled with this dataset.