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International audience; A comprehensive experimental investigation of helicopter blunt fuselage drag reduction using active flow control is being carried out within the Clean Sky project. The objective is to demonstrate the capability of several active technologies to decrease fuselage drag by alleviating the flow separation occurring in the backdoor area of some helicopters (with pronounced ramp for backdoor loading). The work is performed on a simplified blunt fuselage at model scale. Several active flow control actuators are considered for evaluation: steady blowing, unsteady blowing (or pulsed jets), and zero-net-massflux blowing (or synthetic jets). Laboratory tests of each individual actuator are first performed to assess their performance and properties. The fuselage model is then equipped with these actuators distributed in eight slots forming a U-shape on the fuselage backdoor. This paper addresses the promising results obtained during the wind tunnel campaign, since significant drag reductions are achieved for a wide range of fuselage angles of attack. Moreover, a flow control strategy depending on the fuselage attitude is proposed. The link between the best actuation scheme for this attitude and the corresponding flow topology of the backdoor separation is also discussed.

The purpose of this paper is to present an overview of existing actuators at Onera for active flow control. These actuators are used for various applications in wind tunnel tests, from 2D models to half-wing and helicopter models, for external or internal aerodynamics subjects. Depending on the available volume in the models and on the aerodynamic requirements in terms of actuation magnitude and bandwidth from subsonic to transonic conditions, various technical solutions have been retained. There are many ways to classify actuators between mechanical/fluidic, zero-net-massflux/ nonzero mass flux/plasma, etc. The first part of this paper is devoted to mechanical actuators (moving aileron, mini trailing edge devices and deployable vortex generators). Fluidic actuators are presented in the second part, which deals with pulsed fluidic vortex generators, pulsed blowing slots and synthetic jets. The third part is focused on the characterization of the fluidic actuators., Journal Aerospace Lab, Issue 6, June 2013; ISSN: 2107-6596