Aerodynamics and aeroelastics of wind turbines - Wind Power Generation and Wind Turbine Design - page 111

The Reynolds number of a 63-meter length (REpower 5M) blade may reach
6 million and more. A major project was started in 2002 at the UAS Kiel to mea-
sure the aerodynamic properties of a 30% thick slightly modifi ed Delft profi le
[ 22 , 61 , 65 ]. As an outcome avariety of aerodynamic devices were measured as well
as polars up to 10 million. This was achieved by cooling down the tunnel gas to
only 100 K (= -173°C). Figs 22-24 give an impression of the results achieved so
far. An attempt to model the results numerically are reported in [49].

7 Non-standard wind turbines

7.1 Vertical axis wind turbines

Two kinds of unusual turbines are dicussed briefl y below as further examples of
the application of aerodynamics to wind turbines. The fi rst example is a wind

Chord Distributions 1 - 2 MW Turbines

0.1

Blade 1
Blade 2
Blade 3
Blade 4 0.08

0.06

0.04

0.02

0

0 0.2 0.4 0.6 0.8 1

r/R

Figure 21: c / R from four blade sets for a 1.5 MW wind turbine.

Overview Re = 3M Overview Re = 3M

1.5 1.5

Clean
Triping Wird x/l = 0.3 m
Triping Wire x/l = 0.15m
Carborumdum 60
Carbo with VG
Carbo with Gurney Flap
Carobrundum 120
Carobrundum 120 Gurney

1 1

0.5 0.5

Clean
Triping Wird x/l = 0.3 m
Triping Wire x/l = 0.15m
Carborumdum 60
Carbo with VG
Carbo with Gurney Flap
Carobrundum 120
Carobrundum 120 Gurney

0 0

-5 0 5 10 15 0 0.005 0.01 0.015 0.02 0.025

Angle of attack (deg) Drag coefficient

Figure 22: Polars of DU-W-300 mod at Reynolds number 3 million.