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Blade Performance Data
Unloaded GOE222 Profile
Blade Speed Data
Based on 18' Diameter
8 Degree Pitch TSR
7.1 9 Degree
Pitch TSR 6.31
Wind speed
mph RPM Tip speed mph Wind
speed mph RPM Tip speed mph
10 111
71
10 98 63
12 132
85
12 118 76
15 165
106
15 140 95
20 221
142
20 196 126
25 277
178
25 246 158
30 332
213
30 294 189
10 Degree Pitch TSR
5.67 11 Degree
Pitch TSR 5.14
Wind speed
mph RPM Tip speed mph Wind
speed mph RPM Tip speed mph
10 89
57
10 79 51
12 106
68
12 97 62
15 132
85
15 120 77
20 176
113
20 160 103
25 221
142
25 200 129
30 265
170
30 239 154
12 Degree Pitch TSR 4.71
Wind speed
mph RPM Tip speed mph
10 73 47
12 89 57
15 111 71
20 146 94
25 184 118
30 221 142
Useful Formulas
V / R =
I Voltage divided by Resistance = Current
V x I =
W Voltage times current = Watts of power
HP / .00134 =
Watts Horse power divided by .00134 = Watts
Watts x
.00134 = Horse power
1 HP = 550
Foot-lbs of torque
Example:
Our test machine is a 3 phase AC alternator with an 18' foot
diameter 3 - blade set up. The load resistance measures about 5
ohms. The accompaning voltage graph shows voltage at 20 mph is
70 volts.
70 volts
divided by 5 ohms = 14 amps. 70 volts x 14 amps = 980
watts. We multiply this by 3 because of the 3 phases and we get
2940 watts.
1 HP = 747
watts 2940 watts divided by 747watts/hp = 3.9 Horse
power
3.9 hp x
550 ft-lbs/hp =2145 ft-lbs of torque about the wind genertor
axis.
To
calculate the mechanical load on the blade you pick an average
at about 2/3 distance out on the blade. So a 9 foot blade you
would use 6 feet as a lever arm length. 2145 ft-lbs divided
by 3 blades = 715 ft-lbs per blade. 715 ft-lbs divided by 6
feet = 119 lbs force on each blade in the direction of
rotation. 119 lbs x 3 blades is 357 lbs total rotational
force. There is a lot going on up there.
To calculate
Revolutions per minute RPM
Start with
tip speed in mph. Multiply by 5280 feet/mile, then divide by
60 minutes/ hour to get a tip speed of
feet per
minute. Divide this number by the circumference of the blades
to get Revolutions per minute.
Lift
Coefficient
The lift
coefficient ( CL ) is a number associated with a particular shape of an airfoil, and is
incorporated in the lift equation to predict the lift force
generated by the wing using this particular cross section.
CL = L divided
by 1/2 pv squared times A
L is the
lift force, p is the density, v is the speed, q is dynamic
pressure, and A is area.
This is a
complicated equation and concept. Basically when comparing
profiles, the higher lift coefficient the better the lift.
Comparing our Goe 222 profile with another popular profile that
is similar except for the clark Y procile has a flat bottom or
(for wind generators, the front).
Goe 222 lift coef. Clark Y lift coef.
Angle of Attack
0
degrees
.930 .370
4
degrees
1.123 .750
8
degrees
1.438 1.081
These
figures are taken from the Hanley Air Foil program and data
base. The high lift shown in this data is no surprise after
analyzing the wattage and torgue output of our 18 foot diameter
test machine.
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