Engine integration based on multidisciplinary optimisation technique

Abstract

The paper presents the work related to the engine integration of a Rear Fuselage Mounted Engine configuration in the frame of the DLR/Onera project MDOrmec (‘‘Multi-Disciplinary Optimisation of Rear-fuselage Mounted Engine Configuration’’). The developed multidisciplinary optimisation process is based on a mixed-fidelity approach, where the aerodynamics is simulated using CFD methods while the weight, aircraft stability and control are assessed using preliminary design approach. The Breguet mission range is used as the objective value in order to find the best compromise between the aerodynamic performance of the aircraft and its structural weight. The stability and control qualities of the aircraft are also considered in order to ensure similar flight properties as the jet airliner Dornier Do-728, used as reference configuration. The engine-fuselage distance, the longitudinal and the circumferential engine position are used as the design parameters. Since the displacement of the engine impacts the centre of gravity of the aircraft, the longitudinal position of the wing is additionally used as parameter to provide similar longitudinal stability as the reference configuration. In order to ensure the control requirements, the tail planes are automatically sized during the process. The drag coefficient at required lift and zero pitching moment of the full configuration are obtained by using Euler computations at cruise conditions and adapting automatically the angle of attack and angle of incidence of the tail planes. The static margin of the aircraft is also evaluated using Euler computation. The resulting process chain is implemented in the ModelCenter optimisation framework. Finally, the results of the optimisation are presented and discussed in detail.