8
L
L
…tightness of one blade, see diagram
N… number of blades
A... cross-section of the duct
Air-regenerated Noise
V
[m/s]
- air flow volume
L
WA
[dB(A)]
- total level of acoustic power
corrected by filter A
L
W
[dB/Okt.]
- level of acoustic power in the
octave band
f
m
[Hz]
- mean frequencies in the octave bands
2
30
33
35
34
32
25
<25
<25
35
3
40
43
42
39
38
33
25
<25
41
4
46
47
45
44
43
40
32
25
44
6
49
52
51
50
49
45
40
32
49
8
54
55
54
54
53
51
47
39
54
10
57
60
57
60
57
54
52
48
60
