An approach to modelling of Active Gurney Flap (AGF) on a helicopter blade involving the application of the FLUENT code with its capabilities enhanced by the Applicant through User Defined Functions (UDFs) was proposed. The Active Gurney Flap was modelled using UDFs by automatically changing the airfoil or blade section contour and rearranging grid nodes in the zone containing the lower part of the blade. The applied algorithm prohibits harmful distortions of grid cells during AGF operation.
The proposed algorithm was incorporated in the Virtual Rotor (VR) module of UDFs, modelling the kinematics of rotor blades, using the sliding mesh technique available in Fluent, created already and successfully tested by the Applicant. The available in Fluent software models of turbulence and LES/DES schemes were applied in order to find the most suitable approach for the modelling of AGF on a rotor blade. The two- and three-dimensional flow cases described in the Call for Proposals were analysed in this work, including 2D and 3D wind tunnel test cases, whirl tower rotor test cases and rotor forward-flight test cases.
The VR software and all the UDFs used within this project were transferred to the Clean Sky Joint Undertaking with documentation, training, and all test cases.
The project COMROTAG "Development and Testing of Computational Methods to Simulate Helicopter Rotors with Active Gurney Flap" was realised by Institute of Aviation, Warsaw, Poland, based on Clean Sky call for proposals no. JTI-CS-2013-01-GRC-01-014.
The duration of the project, including its extension by Amendment 2 was 38 months, budget was 320 000 EURO with Clean Sky JU financing 75% of the costs. The main requirements of the Call for Proposal were to create dedicated methodology to simulate AGF deployment on both 2D airfoils and 3D helicopter rotors. The developed computational tool had to be validated against a large suite of available test data (that were acquired during several 2D and 3D Wind Tunnel test entries during execution of the project) on standard rotor blade configurations to prove the level of correlation. The testing of the methodology included also ‘blind-cases‘ for a possible future flight tests campaign.
During the execution of the project all planned goals of the project were achieved, including preparation of the computational tool, modelling of two- and three-dimensional flow test cases, verification of the computational results based on the available results of wind-tunnel tests and conducting simulation of “blind cases”. The results of the project were presented on three conferences, including European Rotorcraft Forum and Congress of the International Council of Aeronautical Sciences.