The effect of wind turbine blade tip geometry is numerically analysed using Computational Fluid Dynamics (CFD). Three different rotating blade tips are compared for attached flow conditions and the flow physics around the geometries are analysed. To this end, the pressure coefficient (Cp) is defined based on the stagnation pressure rather than on the inflow dynamic pressure. The tip geometry locally modifies the angles of attack (AOA) and the inflow dynamic pressure at each of the studied sections. However not all 3D effects could be reduced to a change of these two variables. An increase in loadings (particularly the normal force) towards the tip seem to be associated to a spanwise flow component present for the swept-back analysed tip. Integrated loads are ranked to asses wind turbine tip overall performance. It results from the comparison that a better tip shape that produced better torque to thrust ratios in both forces and moments is a geometry that has the end tip at the pitch axis. The work here presented shows that CFD may prove to be useful to complement 2D based methods on the design of new wind turbine blade tips.
[1]
Maureen Hand,et al.
Unsteady Aerodynamics Experiment Phase VI: Wind Tunnel Test Con gurations and Available Data Campaigns
,
2001
.
[2]
Sighard Hoerner.
Aerodynamic Shape of the Wing Tips
,
1952
.
[3]
A. Le Pape,et al.
3D Navier–Stokes computations of a stall‐regulated wind turbine
,
2004
.
[4]
Scott Schreck,et al.
Detached‐eddy simulation of flow around the NREL Phase VI blade
,
2002
.
[5]
Jeppe Johansen,et al.
Numerical Investigation of Three Wind Turbine Blade Tips
,
2002
.
[6]
Niels N. Sørensen,et al.
Navier-Stokes predictions of the NREL phase VI rotor in the NASA Ames 80-by-120 wind tunnel
,
2002
.
[7]
Jeppe Johansen,et al.
Aerodynamic investigation of winglets on wind turbine blades using CFD
,
2006
.
[8]
Earl P. N. Duque,et al.
Navier-Stokes and Comprehensive Analysis Performance Predictions of the NREL Phase VI Experiment
,
2003
.