Wind fence enclosures for infrasonic wind noise reduction

Area of Science:

• Acoustics
• Geophysics
• Environmental Science

Background:

• Infrasound detection is crucial for monitoring nuclear explosions and environmental phenomena like wind turbines.
• Spatial filter arrays face limitations in effectively reducing wind noise at infrasonic frequencies.
• Developing simple, cost-effective wind noise reduction technologies is essential for improving infrasound monitoring.

Purpose of the Study:

• To design and test a large porous wind fence enclosure for optimizing wind noise reduction at infrasonic frequencies (0.01–10 Hz).
• To develop a cost-effective technology that overcomes limitations of existing spatial filter arrays.
• To investigate the impact of various design parameters on wind noise reduction efficiency.

Main Methods:

• Construction and testing of a large porous wind fence enclosure.
• Systematic investigation of enclosure parameters: porosity, top condition, bottom gap, height, diameter, and secondary windscreen.
• Minimizing wind noise by reducing turbulence and velocity gradients inside the fence and area-averaging pressure fluctuations on the surface.

Main Results:

• Optimal wind noise reduction was achieved with surface porosity between 40% and 55%, supplemented by a secondary windscreen.
• The most effective enclosure demonstrated 20–27 dB noise reduction in the 2–4 Hz band.
• Consistent noise reduction of at least 5 dB from 0.1 to 20 Hz and 3–6 dB for turbulence wavelengths larger than the fence was observed.
• Sufficient noise reduction was achieved at high wind speeds (3–6 m/s) to enable microbarom detection.

Conclusions:

• The developed porous wind fence enclosure is a simple and cost-effective solution for significant infrasound noise reduction.
• The technology shows promise for enhancing the detection capabilities of infrasound sources, including nuclear explosions and wind turbines.
• Further optimization of enclosure design parameters can lead to improved performance in various environmental monitoring applications.