AirStreamz vs. Wind Blocking
The importance of materials engineering cannot be overstated. Characteristics like texture, porosity, resistance, permeability, and diffusion are evaluated for wind noise reduction effectiveness across a range of wind speeds and turbulence levels. In this regard, we are the only cycling associated company to hold a wind noise reduction utility patent (#9078482B2 - Sound Permeable Wind Noise Reduction Device).
Our products are made with porous materials that interact with the wind to reduce velocity and turbulence intensity. Porous materials have benefits for flow-control by introducing a fluid permeable medium that modifies the boundary layer, shear layer, and wake characteristics. The penetrable surface absorbs turbulence. In addition, surface flow interaction with the soft fibers reduces velocity and rotational intensity - further reducing wind noise.
Wind Flow Depiction
Passive control of wind velocity / vorticity using porous material vs. bluff body instabilities and wake buffeting.
Figures 1 and 2: Depiction of wind flow interacting with porous material vs. a solid bluff body.
Wind Flow Visualization
The wind flow and interaction characteristics noted above can be seen in the wind tunnel visualizations below:
Images 1 and 2: Visualization of wind flow interacting with porous material vs. a solid bluff body.
Wind Flow Measurements
Using both hot-wires and pressure sensors, wind flow / interaction characteristics noted above are shown below. Velocity and vorticity over the AirStreamz decreases due to the porous material interaction. Wind velocity over the Wind Blocking product accelerates and contributes to wake instabilities / vortices - impacting the outer ear / pinna.
Figures 3 and 4: a) hotwire anemometer placed adjacent to the WNR products. b) Pressure probes placed adjacent to the WNR products and at the rear of the concha. c) sine wave / turbulent pressure fluctuations.
Utilizing Statistical Noise Levels, Ln, L10, L90% - AirStreamz significantly reduce annoying wind noise fluctuations.
Related Academic Research
Turbulence distribution for pile-fabric vs. smooth bluff body and wind tunnel flow visualization (20 mph) by Cat-Ears.
Turbulence is the primary cause of sound in aeroacoustics.
As demonstrated above, porous pile material significantly modifies turbulence.
Cat-Ears / AirStreamz are acoustically transparent - so they are also safer for road cycling.