Development and Validation of Generalized Lifting Line Based Code for Wind Turbine Aerodynamics

Francesco Grasso, Arne van Garrel, Gerard Schepers
2011 49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition   unpublished
In order to accurately model large, advanced and efficient wind turbines, more reliable and realistic aerodynamic simulation tools are necessary. Most of the available codes are based on the blade element momentum theory. These codes are fast but not well suited to properly describe the physics of wind turbines. On the other hand, by using computational fluid-dynamics codes, in which full Navier-Stokes equations are implemented, a strong expertise and a lot of computer time to perform analyses
more » ... o perform analyses are required. A code, based on a generalized form of Prandtl's lifting line in combination with a free wake vortex wake has been developed at Energy research Centre of Netherlands. In the present work, the development of this new code is presented, together with the results coming from numericalexperimental comparisons. The final part of the work is dedicated to the analysis of innovative configurations like winglets and curved blades. Nomenclature α = angle of attack [deg] α i = local angle of attack for wing section i [deg] c = chord [m] c j = chord for wing section j [m] dF = differential aerodynamic force vector dl = directed differential vortex length vector dS i = differential planform area at control point i φ r = azimuth angle [deg] Γ = vortex strength in the direction of r 0 [m 2 s -1 ] L = Lift [N] r 0 = vector from beginning to end of vortex segment r 1 = vector from beginning of vortex segment to arbitrary point in space r 2 = vector from end of vortex segment to arbitrary point in space ρ = fluid density [kg m -3 ] u ai = chordwise unit vector at control point i u ni = normal unit vector at control point i u = axial component local velocity [m s -1 ] v = in plan horizontal component local velocity [m s -1 ] V = local fluid velocity [m s -1 ] V ∞ = velocity of the uniform flow or free stream [m s -1 ] v ij = dimensionless velocity induced at control point j by vortex i , having a unit strength ω = vortex strength [ s -1 ] w = in plan vertical component local velocity [m s -1 ]