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Dr Con Doolan, University of Adelaide: Developing a quieter wind turbine – Understanding the effects of blade generated turbulence and noise
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Dr Con Doolan, University of Adelaide: Developing a quieter wind turbine – Understanding the effects of blade generated turbulence and noise

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Dr Con Doolan, Associate Professor, University of Adelaide delivered this presentation at 2013 Australian Wind Energy Conference. The event gave conference attendees key insights into how the new …

Dr Con Doolan, Associate Professor, University of Adelaide delivered this presentation at 2013 Australian Wind Energy Conference. The event gave conference attendees key insights into how the new Abbott Government may impact future developments in the industry. The conference has a long-standing history of bring together key policy stakeholders, government representatives, project developers, energy companies and regulators. For more information about the annual event, please visit the conference website: https://www.informa.com.au/windenergyconference.

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  • 1. Developing a quieter wind turbine – Understanding the effects of blade generated turbulence and noise Associate Professor Con Doolan School of Mechanical Engineering University of Adelaide, SA 5005 1
  • 2. The Flow and Noise Group: What we do • Fundamental and applied research in the area of flow-induced noise (aeroacoustics/hydroacoustics) • Application areas: Jet noise/airframe noise/helicopter noise/wind turbines/submarine noise/automotive wind noise/fan noise… • 3 Postdocs • ~11 HDRs
  • 3. Facilities • • • • • Anechoic Wind Tunnel Anechoic Chamber Reverb Chamber Large Wind Tunnel Excellent Acoustic Instrumentation, including arrays and high-channel-count DAQ systems • World-class flow instrumentation, hot-wire, laser diagnostics, surface pressure, etc • Supercomputer facilities
  • 4. Anechoic Wind Tunnel Outlet: 275 mm x 75 mm Velocity Range: 3-38 m/s T.I. = 0.3% Fan Anechoic Chamber Collector Silencer Diffuser Settling Chamber Slide 4 Contraction
  • 5. Dual Beamforming Arrays Acoustic “image” for wall-mounted hydrofoil
  • 6. Adelaide Wind Tunnel •Cross-section area: 2.75 x 2 square metres •Maximum air speed: 50 m/s (180 km/h) •Turbulence intensity: less than 0.8%
  • 7. Wind Turbine Wind Tunnel Measurements: about to start
  • 8. Projects Turbulent/Laminar edge Airfoil/Hydrofoil Noise noise Jet Noise Wall Mounted Air/Hydrofoils RANS-Based CAA CAA/DNS CFD Flow Wind Turbines Hydrofoil Flow Recessed Hydrophone Cavity/Feedback Loop
  • 9. Wind Turbine Noise: Why is it important? • Noise emissions are regulated • Lower turbine noise emissions can ease planning and possibly allow greater numbers of turbines • Community engagement: sometimes the issue of noise becomes emotive and can affect planning approval • Quality scientific advice required based on evidence 9
  • 10. This talk… • • • • • • How is wind turbine noise generated? Blade Swish Multiple Turbines Atmospheric effects Trailing edge noise control Future Challenges 10
  • 11. Wind Turbine Unsteady Aerodynamics and Noise Wind turbine blade Convected atmospheric turbulence Gearbox Incoming turbulent atmospheric boundary layer Blade passes tower as it rotates Tower 11
  • 12. Blade Tip Tip vortex Blade motion Boundary layer turbulence passing over trailing edge Blade boundary layer Trailing edge Atmospheric turbulence ahead of moving blade 12
  • 13. Spectral Content and Sources 13
  • 14. Airfoil Noise Flow Turbulence interaction with trailing edge: Noise Turbulence interaction with leading edge: Noise
  • 15. Airfoil noise is… • Hard to predict – Turbulent structure, statistics, anisotropic, nonhomogeneous, adverse pressure gradient – too much reliance on empirical models – Laminar/Transitional Tonal noise: controversial area – feedback loop or global instability with facility effects? • Hard to measure – Broadband signal, sometimes hard to distinguish from other sources – Requires sophisticated techniques: multi-microphone, beamforming arrays – time reversal? • Hard to control – Passive noise control methods are difficult to implement and don’t agree with theoretical predictions.
  • 16. Swish? Trailing Edge Noise Directivity + Convective Amplification 16
  • 17. Phased Array Measurements* *Oerlemans, S., Sijtsma, P. & Mendez Lopez, B., 2007. Location and quantification of noise sources on a wind turbine. Journal of Sound and Vibration, 299(4-5), pp.869–883. 17
  • 18. Propagation & Weather Effects 18
  • 19. Atmospheric Boundary Layer Night Day van den Berg, G., 2004. Effects of the wind profile at night on wind turbine sound. Journal of Sound and Vibration. 19
  • 20. Terrain Effects Son, E. et al., 2010. Integrated numerical method for the prediction of wind turbine noise and the long range propagation. Current Applied Physics, 10(S), pp.S316–S319. 20
  • 21. Reinforcement Model 21
  • 22. Owls: Slient Flight – Silent Turbines? Tyto Alba – Barn Owl Sarradj et al. (2010) 16th AIAA/CEAS Aeroacoustics Conference, Stockholm, June.
  • 23. Noise Control: Trailing Edge Serrations Oerlemans et al. Reduction of Wind Turbine Noise Using Optimized Airfoils and Trailing-Edge Serrations. AIAA JOURNAL (2009) vol. 47 (6) pp. 1470-1481
  • 24. Noise Control: Numerical Optimisation of Blades Marsden et al. Trailing-edge noise reduction using derivative-free optimization and large-eddy simulation. Journal of Fluid Mechanics (2007) vol. 572 pp. 13
  • 25. Noise Control: Trailing Edge Modifications Porous Trailing Edge Brushes HERR and DOBRZYNSKI. Experimental investigations in low-noise trailing-edge design. AIAA Journal (2005) Geyer et al. Measurement of the noise generation at the trailing edge of porous airfoils. Experiments in Fluids (2010) vol. 48 (2) pp. 291-308
  • 26. Passive Control: Serrations Mean Chord = 165 mm Re = 160,000 – 420,000
  • 27. Experiment Narrow serrations with λ = 3 mm. Wide serrations with λ = 9 mm. Theory
  • 28. Active Control? • Amplitude modulation MAY be caused by timevarying reinforcement of nearly synchronised blade motion • Can this be overcome by phase de-synchronisation? • What mechanism dominates – Trailing edge noise? • How many turbines in a row contribute? • Can an active control system be devised? 29
  • 29. Future Challenges Re  9-25 Million Blade Reynolds number Increases with Capacity UpWind: Design limits and solutions for very large wind turbines, EU 6th Energy Framework, March 2011 Slide 30
  • 30. Highest Reynolds No. Data we have… 140 NASA 81, Re = 2.88e6 IAG, Re = 2.8e6 VT, Re = 3.05e6 135 SPL1/3 Scaled (dB) 130 125 120 115 110 105 100 95 10 − 1 10 0 St More fundamental experiments are needed to properly understand blade noise, at higher Reynolds number, with better techniques. 31
  • 31. Peak radiating frequency vs Size 6000 5000 fpeak (Hz) 4000 3000 2000 Error ≈ 30% 1000 0 0 2 4 6 Re/10 SIZE 8 10 6 32
  • 32. Thanks • Australian Research Council, ASC, DSTO, US Air Force, the Sir Ross and Sir Keith Smith Fund • All my postgrads and postdocs for making me look good Questions?