Applied Aerodynamics

Drag Reduction Technologies for Civil Transport Aircraft

	Cross flow kinetic energy at cruise downstream of several wing tips

Drag reduction is one of the main objectives of the transport aircraft manufacturers. The drag breakdown of a transport aircraft at cruise shows that the skin friction drag and the lift-induced drag constitute the two main sources of drag, approximately one half and one third of the total drag. Hybrid laminar flow technology and innovative wing tip devices offer the greatest potential for drag reduction. Aircraft performance improvement in off-design conditions can also be obtained through trailing edge optimisation, control of the shock boundary layer interaction and of the boundary layer separation. The research activities carried out in the Applied Aerodynamic department are related to the different mentioned topics with the aim of evaluating the potential gains offered by the different technologies. Some results are presented in the following paper (Overview on Drag Reduction Technologies for Civil Transport Aircraft).

The novel drag reduction techniques have been developed these last years at the Applied Aerodynamics department using RANS solvers and "far-field" drag extraction. Drag, or a drag component, given by an expression involving surface or volume integrals within the flow-field (and not only at the solid surface), is called "far-field" drag. Far-field formulations are based on basic conservation laws and thermodynamic considerations. This approach to the extraction of drag has the advantage, in applied aerodynamics and more particularly in aerodynamic shape design, of yielding a physical breakdown of the drag (viscous drag, wave drag, induced drag) and local data about the drag sources.

Control volumes for the integration of far-field drag

Last Update:22 March 2006 - © ONERA 2009 - Terms of use