Wings of modern civil airliners are designed for two distinct and very different flight phases: Cruise and low-speed-flight. As an aircraft spends the majority of each mission in cruise, this is what its aerodynamics are optimized for. In order to generate sufficient lift during low-speed flight phases, namely take-off and landing, concurrent aircraft are equipped with mechanical high-lift devices (e.g. slats and flaps), which extend the flight envelope. While, for decades, those devices resolved the dilemma of having to cover efficiently for high- and low-speed flight, recent developments in aircraft design have turned up new problems that require a different solution. In particular, one novel design features conflicts with the local integration of mechanical high-lift devices at the wing’s leading edge: ultra-high-bypass ratio fans (UHBR). The large nacelles of UHBR engines need to be installed close to the wing to provide sufficient ground clearance without increasing the size of the aircraft’s landing gear. In consequence, a slat would collide with the nacelle when deployed, resulting in the need of a slat cut-out, the fraction of the wing’s span above the engine where no slat is installed. This leaves regions of the wing unprotected by a slat and prone to separation at incidence angles much lower than for the remaining sections of the wing. It is in those regions where Active Flow Control (AFC) can be introduced to delay local separation to higher angles of attack and therefore to augment the overall high-lift system.

The aim of flow control is, generally speaking, to modify this original state of flow in such a manner that beneficial effects are achieved. Besides the in-depth understanding of the flow physics involved, successful application of active flow control requires the availability of robust, reliable and potent flow control actuators. The project DECOROUS addresses the development of such actuators, namely of a two-stage no-moving-parts fluidic actuator system for use in active flow control applications at the wing-pylon junction of civil airliners.

The project exploits numerical and experimental methods to develop the flow control actuator system.

This project has received funding from the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 715796.