Passive Flow Control on Civil Aircraft Flaps Using Sub-Boundary Layer Vortex Generators in the AWIATOR Programme

Abstract

The objective of this work was to examine the use of passive flow control, Sub Boundary Layer Vortex Generators (SBVGs), to allow the increase of the maximum flap angle on a civil aircraft from 32 to 35 degrees. If achieved this gives the potential to improve the high lift performance (lift) at landing without incurring a drag penalty at cruise and take-off. Previous work has shown that while a 35 degree flap angle shows a favorable increase in lift the flap is highly separated. In the AWIATOR programme an array of SBVGs was designed and then optimised and demonstrated in wind tunnel tests. Finally the optimised array was validated in a series of flight tests on an A340-300 test aircraft. The flight test results demonstrated, at aircraft scale, that by reducing flap separation SBVGs can be used to allow low speed improvements associated with increased flap angle to be exploited on a civil aircraft. The increase in flap angle leads to an increase in lift in landing (by approx 2.5%) across the incidence range (from 32 without SBVGs to 35 with SBVGs). _____________________________________________________________________________________________