Recent collaborative research efforts (BRITE-EURAM UNSI, DFG-SFB557) particularly focus upon the modelling of unsteady turbulent flows based on Reynolds-averaged Navier-Stokes (RANS) equations. Attention is drawn to the simulation of both natural and forced unsteadiness, with specific emphasis on vortex shedding past bluff bodies (c.f. related Vortex-Shedding link on this site) and the prediction of dynamic airfoil/wing behaviour. Examples included under this link refer to the simulation of turbulent flow around pitching aerodynamic devices. |
The activities of the BRITE-EURAM UNSI
concentrate on Unsteady Navier-Stokes simulations in the context of
Fluid/Structure Interaction. The focal point of our contribution are turbulence
modelling and CSM-CFD coupling aspects (c.f. Fluid/Structure link on this site).
A simple, however, instructive application is the computation of an oscillating
NACA 0015 airfoil featuring dynamic stall, where a large database of experimental results is
available from NASA (Piziali, 1994) [1].
Under the umbrella of the SFB 557 project A2 the effect of a movable flap mounted to an airfoils upper surface on the onset of static stall is investigated. Experimental investigations display that airfoil stall at high angles of attack can be delayed by such kind of self adjusting flaps. The flap essentially supresses the flow reversal which yields an increase of the maximum angle of attack. Due to an attenuated onset of massive flow separation an improved plane handling is obtained beyond the maximum angle of attack. |
[1] A.R. Piziali: An experimental
investigation of 2D and 3D oscillating wing aerodynamics for a range of
angles of attack including stall, NASA TM 4632, 1994.
[2] I, Demirdzic, M. Peric: Space conservation law in finite volume calculations of fluid flow , Int. J. Num. Meth. in Fluids, Vol. 8, 1988. [3] J.A. Ekaterinaris, M.F. Platzer: Computational prediction of airfoil dynamic stall , Prog. Aerospace Sci, Vol. 33, 1997. [4] T. Rung, F.Thiele: Computational Modelling of Complex Boundary-Layer Flows , 9th Int. Symp. on Transport Phenomena in Thermal-Fluid Eng., Singapore, 1996. [5] P.R. Spalart, S.R. Allmaras: A One-Equation Turbulence Model for Aerodynamic Flows, AIAA Paper 92-0439, 1992. [6] D.C. Wilcox: Reassesment of the scale determing equation for advanced turbulence models, AIAA Journal, 1988. [7] T. Rung: Erweiterung von Eingleichungs- Turbulenzmodellen fuer lokales Nichtgleichgewicht, Institutsbericht Nr. 03/98, Hermann-Foettinger-Institut, Berlin, 1998. |
Background |
Dynamic Stall | Comp. Approach | Results | Animations |