Community Research and Development Information Service - CORDIS


DEMOS — Result In Brief

Project ID: 338523
Funded under: FP7-JTI
Country: Italy

Active rotor blades for helicopters

Advanced morphing technologies adapt the aerodynamic properties of helicopter blades to local airflow conditions. EU-funded researchers have developed a large-scale demonstrator to validate the effectiveness of such an innovative system, promising to bring the smart helicopter one step closer.
Active rotor blades for helicopters
Of the active rotor systems under development, the active Gurney flap (AGF) system has been selected for the Clean Sky initiative's Green Rotorcraft Integrated Technology Demonstrator. AGF enables a helicopter to operate with reduced tip speed of the main rotor while preserving the current flight capabilities.

Designed to be integrated into commercial helicopter blades, AGF is expected to withstand real in-flight vibrations and aerodynamic loads. However, the integration of this system in helicopter rotor blades is not straightforward, given the enormous forces generated by the rotor blade rotation.

Within the EU-funded project DEMOS (Design and manufacturing of a pitch-oscillating system for Gurney flap testing), researchers have designed and manufactured a test rig to study the effectiveness of the AGF in mitigating the dynamic stall phenomenon.

The system consists of a 2D blade section model with a chord of 0.4 m activated by a torque motor remotely controlled to generate the desired pitch-oscillating motions. The airfoil was designed to be installed in the state-of-the-art icing wind tunnel of the Italian Aerospace Research Centre (CIRA).

The wind tunnel campaign was scheduled at the end of 2014. The aim was to investigate the dynamic stall phenomenon on the 2D pitch-oscillating airfoil equipped with AGF systems. The baseline configuration of the AGF was composed of a T-shape gurney flap driven by two magnetic linear motors.

During the tests, surface pressure measurements as well as load cells measurements were performed. Based on the results under different aerodynamic and inertial loads, it was possible to obtain experimental confirmation of the prototype AGF system's reliability in real flight conditions.

The DEMOS project has made an important contribution to answering key questions about the dynamic stall phenomenon in helicopters and offered a possibility to improve their aerodynamic performance. The AGF technology represents a most effective way to reduce drag and vibrations and, thereby, the noise generated by rotorcraft.

Related information


Rotor blades, helicopters, active Gurney flap, Clean Sky, aerodynamic loads, DEMOS
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