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Numerical studies of active flow control on wing tip extension

Petr Vrchota (Department of Aerodynamics, VZLU - Czech Aerospace Research Centre, Prague, Czech Republic)
Ales Prachar (Department of Aerodynamics, VZLU - Czech Aerospace Research Centre, Prague, Czech Republic)
Shia-Hui Peng (Swedish Research Agency, FOI, Stockholm, Sweden)
Magnus Tormalm (Swedish Research Agency, FOI, Stockholm, Sweden)
Peter Eliasson (Department of Aeronautics, Saab AB, Stockholm, Sweden)

Aircraft Engineering and Aerospace Technology

ISSN: 0002-2667

Article publication date: 16 January 2019

Issue publication date: 6 March 2019




In the European project AFLoNext, active flow control (AFC) measures were adopted in the wing tip extension leading edge to suppress flow separation. It is expected that the designed wing tip extension may improve aerodynamic efficiency by about 2 per cent in terms of fuel consumption and emissions. As the leading edge of the wing tip is not protected with high-lift device, flow separation occurs earlier than over the inboard wing in the take-off/landing configuration. The aim of this study is the adoption of AFC to delay wing tip stall and to improve lift-to-drag ratio.


Several actuator locations and AFC strategies were tested with computational fluid dynamics. The first approach was “standard” one with physical modeling of the actuators, and the second one was focused on the volume forcing method. The actuators location and the forcing plane close to separation line of the reference configuration were chose to enhance the flow with steady and pulsed jet blowing. Dependence of the lift-to-drag benefit with respect to injected mass flow is investigated.


The mechanism of flow separation onset is identified as the interaction of slat-end and wing tip vortices. These vortices moving toward each other with increasing angle of attack (AoA) interact and cause the flow separation. AFC is applied to control the slat-end vortex and the inboard movement of the wing tip vortex to suppress their interaction. The separation onset has been postponed by about 2° of AoA; the value of ift-to-drag (L/D) was improved up to 22 per cent for the most beneficial cases.

Practical implications

The AFC using the steady or pulsed blowing (PB) was proved to be an effective tool for delaying the flow separation. Although better values of L/D have been reached using steady blowing, it is also shown that PB case with a duty cycle of 0.5 needs only one half of the mass flow.


Two approaches of different levels of complexity are studied and compared. The first is based on physical modeling of actuator cavities, while the second relies on volume forcing method which does not require detailed actuator modeling. Both approaches give consistent results.



The work described in this paper has received funding from the European Community’s 7th Framework Programme FP7/2007-2013, under grant agreement no. 604013, AFLoNext project. This work was also supported by The Ministry of Education, Youth and Sports of the Czech Republic from the Large Infrastructures for Research, Experimental Development and Innovations project “IT4Innovations National Supercomputing Center – LM2015070.”


Vrchota, P., Prachar, A., Peng, S.-H., Tormalm, M. and Eliasson, P. (2018), "Numerical studies of active flow control on wing tip extension", Aircraft Engineering and Aerospace Technology, Vol. 91 No. 2, pp. 346-352.



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