Development and analysis of vertical-axis wind turbines - Wind Power Generation and Wind Turbine Design - page 294

1.4

TSR = 2.0
TSR = 4.0
TSR = 6.0

ˆ

1.2

1.0

0.8

0.6

0.4

0.2

0.0

-135 -90 -45 0 45 90 135 180 225 270

Blade equatorial angle, b (º)

-0.2

Figure 13: Non-dimensional torque coeffi cient, ˆ Q as a function of blade azimuth
angle, b estimated from a double-multiple-streamtube blade element
analysis of a VAWT (parameters as for Fig. 12).

0.5

NACA0012 Re = 1.0E+06
NACA0012 Re = 0.5E+06
NACA0012 Re = 0.25E+06
NACA0018 Re = 1.0E+06

0.4

0.3

C p

0.2

0.1

0

0 1 2 3 4 5 6 7 8 9

Tip speed ratio, λ

Figure 14 : Double-multiple-streamtube results for the coeffi cient of performance,
C p , as a function of tip speed ratio, l , for a straight-bladed VAWT tur-
bine operating with different mean blade Reynolds numbers (solidity
cN / R = 0.15, NACA0012 and 0018 profi les, with lift and drag data
from [ 46 ]).