21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-2.3.1

AERODYNAMIC DESIGN OPTIMISATION APPLIED TO CIVIL TRANSPORTS WITH UNDERWING MOUNTED ENGINES

Hackett K. C., Rees P. H.*, Chu J. K.*
DERA, United Kingdom; * Bae Airbus Ltd, United Kingdom

Keywords: aerodynamic, civil transport, undewing engine, design

The problem of achieving an aerodynamically successful nacelle installation can be particularly difficult in the case of Long Duct Mixed Flow (LDMF) nacelles. Very large interference drag penalties can arise if an integrated design approach is not applied. LDMF nacelles have the benefit of reducing noise and improving specific fuel consumption due to the mixing process of the fan and core exhaust gases. Consequently, using an example of this type of nacelle, this paper describes an investigation that was undertaken with the following aims: -By wind tunnel testing, to investigate the effect on installation of aerodynamic parameters such as Reynolds number, Mach number, and geometric parameters such as degree of wing/nacelle coupling, and pylon/nacelle alignment -To assess CFD analysis methods for their ability to predict the aerodynamic effects of varying the key geometric parameters associated with closely coupled engine installations. -By using conventional design techniques, and engineering judgement, to design a wing which is tolerant to closely-coupled engine installations. -To develop and demonstrate an automated design optimisation-methodology targeted at minimising interference effects.

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