Environmental Engineering Reference
In-Depth Information
Table 3.1 Blade geometry
from Anderson et al. [ 2 ]
Radius (cm)
Chord (cm)
Twist ()
13.33
25.02
24.21
23.25
23.18
21.06
29.75
19.98
15.87
36.25
17.32
11.92
42.75
15.12
8.96
49.25
13.33
6.77
55.75
11.86
5.18
62.25
10.67
4.02
68.75
9.71
3.16
75.25
8.92
2.49
81.75
8.26
1.93
88.25
7.71
1.44
94.75
7.23
0.99
101.25
6.80
0.59
107.75
6.41
0.25
114.25
6.04
-0.06
120.75
5.70
-0.36
127.25
5.38
-0.67
133.75
5.08
-0.98
140.25
4.84
-1.28
146.75
4.66
-1.59
150.0
4.60
-1.74
The main ''program'', simple_power_calc.m has the single input argument of
the number of blades ( Numb ). All blade elements have the same radial width, dr.
tcdist.m determines the chord and twist distributions for any number of blade
elements. The particular polynomial equations for the chord and twist are a fit to
the data for a two-bladed 3 m diameter turbine that was extensively field- and
wind-tunnel tested by Anderson et al. [ 2 ], see the listings in Table 3.1 . The
measurements of the turbine's performance will be discussed in detail in Chap. 5 .
Note that tcdist.m allows the user to specify a pitch angle, which is a global,
constant alteration to the twist.
Having read in the blade geometry, simple_power_calc.m begins an outer
loop to allow the user to vary the windspeed ( U0 ) and then the tip speed ratio
( lambda ) in the inner loop. The lift and drag coefficients from the subroutine
in LandD_0012.m which contains data fits for the NACA 0012 profile are
discussed in the next chapter. These fits are restricted both in angle of attack
( aoa ) and Reynolds number ( Re ) and should never be used outside their range
of validity.
The iteration is extremely simple: the new and old values of a ( a ) are simply
averaged to find the appropriate values for the next iteration. Convergence in a is
determined using the tolerance, tol .
The listing of simple_power_calc.m follows:
Search WWH ::




Custom Search