Today leading edge CFD (computational fluid dynamics) software systems are available which are capable of predicting the viscous flow around main rotor-fuselage configurations or even complete helicopters.
|Sixth Framework Programme|
|Fig. 1: The GOAHEAD helicopter wind tunnel model|
The greatest shortcoming for qualifying these methods as design tools in the industrial design process is the lack of detailed experimental validation data for the aerodynamics of complete helicopters.
In order to establish a CFD validation database for helicopters, the GOAHEAD project was formed by 15 partners. The main objectives of GOAHEAD are:
- To enhance the aerodynamic prediction capabilities of Europe's helicopter industry with respect to complete helicopter configurations.
- To create an experimental database for validation of 3D CFD unsteady Reynolds-averaged Navier-Stokes (URANS) methods for unsteady viscous flows including rotor dynamics for complete helicopter configurations, (main rotor-fuselage-tail rotor) with emphasis on viscous phenomena like flow separation and transition from laminar to turbulent flow.
- To evaluate and validate Europe's most elaborate URANS solvers for the prediction of viscous flow around complete helicopters including fluid-structure-coupling.
- To establish best practice guidelines for the numerical simulation of the viscous flow around helicopter configurations.
The experimental database in combination with the validated CFD models will allow new helicopter designs to be assessed in a considerably reduced time span without the need for large corrections after flight testing.
The GOAHEAD project has a duration of four years (July, 1st, 2005 – June 30th, 2009). Funding for the project is granted by the European Commission within the 6th framework programme, priority theme 4 “Aeronautics and Space”.
Outline of workplan
The configuration under consideration is a Mach scaled model similar to a modern transport helicopter consisting of the main rotor, the fuselage (including all control surfaces) and the tail rotor, see Figure 1. The model has a length of 4.15 m and a rotor diameter of 4.20 m. Experimental data for the configuration will be gathered at the DNW LLF wind tunnel in Marknesse, The Netherlands. The measurements will comprise global forces, steady and unsteady pressures, transition positions, stream lines, position of flow separation, velocity fields in the wake, vortex trajectories and elastic deformations of the main rotor blades. The experimental results will be analysed in detail and the data will be stored in an exhaustive, well documented data base.
In parallel to the wind tunnel experiment numerical flow simulations will be performed. Within a blind test phase prior the wind tunnel experiment the flow solvers will be used to predict the flow for the helicopter. As soon as experimental data are available the data will be use to evaluate the CFD solvers. In a post test phase the CFD simulations will be rerun using refined grids, models etc. in order to improve the correlation between CFD and experimental results. The know-how obtained during the CFD application will be documented in best practice guidelines.
The GOAHEAD project is formed by 15 partners (five national research centres, five universities, four helicopter manufacturers and one SME (small or medium enterprise)):
- CIRA, Centro Italiano Ricerche Aerospaziali S.C.P.A., Italy
- DLR, Deutsches Zentrum für Luft- und Raumfahrt e.V., Germany
- FORTH, Foundation for Research and Technology, Greece
- NLR, Stichting Nationaal Lucht-en Ruimtevaartlaboratorium, The Netherlands
- ONERA, Office National d’Etudes et de Recherches Aérospatiale, France
- Cranfield University, United Kingdom
- Politecnico di Milano, Italy
- Universität Stuttgart, Germany
- University of Glasgow, United Kingdom
- University of Liverpool, United Kingdom
- Agusta S.p.A., Italy
- EC SAS, EUROCOPTER S.A, France
- ECD, EUROCOPTER Deutschland G.m.b.H., Germany
- Westland Helicopter, United Kingdom
- Aktiv Sensor GmbH, Germany
The project is coordinated by DLR (Institute of Aerodynamics and Flow Technology).