The sounds of high winds

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The sound of high winds: the effect of atmospheric stability on wind turbine sound and microphone noise G.P. van den Berg Cover photograph by Richard de Graaf
Contents I WIND POWER, SOCIETY, THIS BOOK: an introduction 1 I.1 A ‘new’ phenomenon 1 I.2 Digging deeper 4 I.3 Commercial and policy implications 6 I.4 Large scale benefits and small scale impact 9 I.5 Microphone wind noise 12 I.6 Research aims 13 I.7 Text outline and original work 13 II ACOUSTICAL PRACTICE AND SOUND RESEARCH 17 II.1. Different points of view 17 II.2 Results from our wind turbine research 18 II.3 Early warnings of noisy wind turbines? 19 II.4 The use of standard procedures 21 II.5 Modelling versus measurements 23 II.6 Conclusion 24 III IV BASIC FACTS: wind power and the origins of modern wind turbine sound 27 III.1 Wind energy in the EU 27 III.2 Wind profiles and atmospheric stability 27 III.3 Air flow on the blade 32 III.4 Main sources of wind turbine sound 33 LOUD SOUNDS IN WEAK WINDS: effect of the wind profile on turbine sound level 39 IV.1 The Rhede wind farm 39 IV.2 Noise impact assessment 41 IV.3 Wind turbine noise perception 42 IV.5 Measurement instruments and method 43 IV.6 Results: sound emission 43 IV.7 Results: sound immission 45 ii
Page 1 and 2: The sounds of high winds the effect
Page 3: Promotores: prof dr ir H. Duifhuis
Page 7 and 8: VII THINKING OF SOLUTIONS: measures
Page 10 and 11: I WIND POWER, SOCIETY, THIS BOOK: a
Page 12 and 13: esidents) noticed the discrepancy b
Page 14 and 15: that even though wind turbines did
Page 16 and 17: legitimate problems [Wolsink 1990].
Page 18 and 19: Thinking that this could perhaps be
Page 20 and 21: gas must keep flowing” . 1 I do n
Page 22 and 23: sound and the noise that wind produ
Page 24: combined with the corresponding sec
Page 27 and 28: calculated one and whether sound ch
Page 29 and 30: annoying turbine sound at distances
Page 31 and 32: was 57.9 dB, with a maximum deviati
Page 33 and 34: not correct at night, although the
Page 36 and 37: III BASIC FACTS: wind power and the
Page 38 and 39: 0.1. In a stable atmosphere vertica
Page 40 and 41: With regard to wind power some atte
Page 42 and 43: III.4 Main sources of wind turbine
Page 44 and 45: High frequency: trailing edge (TE)
Page 46: So, what's the sound like...? (....
Page 49 and 50: Figure IV.2: turbines (dots W1….W
Page 51 and 52: L Wj , assumed identical for all k
Page 53 and 54: IV.1. As explained above, the wind
Page 55 and 56:
sound level in the measurement inte
Page 57 and 58:
Leq,5 min in dB(A) 50 45 40 35 30 A
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The same lines as in figure IV.5B,
Page 61 and 62:
at hub height, not to a variation i
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IV.10.1 Measured and calculated imm
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wind farm to the measurement locati
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spherical divergence, that is: prop
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Thus, the logarithmic wind profile,
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There are now three factors influen
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direction may change significantly.
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V.2 Measurement results V.2.1 Locat
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P48 microphone. The sound was then
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1/3 octave band Lp in dB 1/3 octave
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1 1 0 1 0 0 1 0 0 0 1 0 0 0 0 A B 8
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same magnitude as close to the turb
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In figure V.5 the equivalent 1/3 oc
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Also plotted in figure V.7 is the v
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V.3 Perception of wind turbine soun
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kHz. For wind turbines we found tha
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V.4 Conclusion Atmospheric stabilit
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VI STRONG WINDS BLOW UPON TALL TURB
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(hub height) wind velocity is 4 m/s
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For the hourly progress of wind vel
Page 102 and 103:
In figure VI.5 the frequency distri
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when V 80 was over 4 m/s. Such a de
Page 106 and 107:
dunes on the North Sea coast, Vliss
Page 108 and 109:
when based on extrapolated wind vel
Page 110 and 111:
The differences between actual and
Page 112 and 113:
hours. This corresponds to an avara
Page 114 and 115:
VII THINKING OF SOLUTIONS: measures
Page 116 and 117:
stability. The turbine thus operate
Page 118 and 119:
sound level was measured close to a
Page 120 and 121:
This type of control can also be ac
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consecutive periods of 15 minutes i
Page 124 and 125:
increase of blade pitch with tilt (
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elatively quiet areas as it control
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VIII RUMBLING WIND: wind induced so
Page 130 and 131:
Finally, in this overview, Boersma
Page 132 and 133:
The friction created by wind shear
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the eddy relative to the screen sur
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(L at,1/3 ~ -26.7·logf), but press
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VIII.3 Comparison with experimental
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the small size of the unscreened mi
Page 142 and 143:
A B reduced pressure level Lred (dB
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microphone, in a 9 cm foam cylinder
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plotted is the calculated screening
Page 148 and 149:
VIII.5 Applications As microphone w
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IX GENERAL CONCLUSIONS The research
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modulation frequencies close to 4 H
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Results from various onshore, relat
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limits, but nighttime immission lev
Page 158 and 159:
X EPILOGUE This is the end of my to
Page 160 and 161:
“….. about 80 per cent of the p
Page 162 and 163:
ACKNOWLEDGMENTS I want to express m
Page 164 and 165:
SUMMARY Ch. III Ch. II Ch. I This s
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and as a result layers of air are l
Page 168 and 169:
500 kW. However, based on the real,
Page 170 and 171:
well known for an unobstructed wind
Page 172 and 173:
SAMENVATTING Bobby vraagt: 'Hoort u
Page 174 and 175:
Vaak wordt aangenomen dat er een va
Page 176 and 177:
gebleken dat de menselijke gevoelig
Page 178 and 179:
Bij een windpark kunnen de fluctuat
Page 180 and 181:
REFERENCES Archer C.L. and Jacobson
Page 182 and 183:
Kerkers A.J. (1999): “Windpark Rh
Page 184 and 185:
Petersen E.L., Mortensen N.G., Land
Page 186 and 187:
Van Ulden, A.P. and Wieringa J. (19
Page 188 and 189:
APPENDICES 179
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dB(G): unit of level after G-weight
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u f : rms longitudinal component of
Page 194 and 195:
downwind turbine with an 80 m tubul
Page 196 and 197:
and total trailing edge immission s
Page 198 and 199:
So for a modern turbine at high spe
Page 200 and 201:
45 wind E (100 gr) 20 Leq (A) Leq,5
Page 202 and 203:
Wiens brood men eet, ….. Een plei
Page 204 and 205:
Vochtproblemen in woningen Venuslaa
Page 206 and 207:
Geluidsbelasting van een windturbin
Page 208 and 209:
Metingen van laagfrequent geluid in
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