Accurate wake modeling is crucial for the prediction of rotorcraft aerodynamics, dynamics and acoustics. Recent advances in Computational Fluid Dynamics (CFD) have improved predictive capability in these areas but at too high a computational cost. This is because excessive numerical dissipation in CFD solutions necessitates the use of very fine resolution grids to maintain the wake vorticity. A technique called vorticity confinement (VC) has been developed that can solve this problem. VC modifies the system of equations to implicitly confine the spread of vorticity while maintaining conservation laws. Properly applied, vorticity confinement can provide two orders of magnitude reduction in grid resolution requirements. This paper describes the development of a new CFD rotorcraft aerodynamics solution method to provide the high accuracy of CFD at drastically reduced computation times from standard methods making the simulation usable for engineering design/analysis. The solution has been parallelized and in this form can provide high resolution rotor wake solutions in two minutes per rotor revolution using 32 processors. Also described in this paper are enhancements to the vorticity confinement method that allow modeling of surfaces as 'immersed' within the flow (e.g. fuselages and the ground) and specialized coding to accelerate hover performance calculations. VC can be easily coupled with comprehensive rotorcraft analysis tools and is being coupled with the U.S. Army's Rotorcraft Comprehensive Analysis System (RCAS) as part of this work. Sample hover performance and forward flight airload predictions are presented.
A rotorcraft aerodynamics CFD solution method based on vorticity confinement
Ein CFD-Verfahren zur Beschreibung der Hubschrauber-Aerodynamik basierend auf Wirbeleinschließung
AHS International Annual Forum, 66 ; 1349-1364
2010
16 Seiten, 23 Bilder, 34 Quellen
Aufsatz (Konferenz)
Englisch
A Rotorcraft Aerodynamics CFD Solution Module using Vorticity Confinement
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