Large porous wind barriers as a mitigation technique for turbulence induced infrasonic noise

Abstract

An infrasonic wind barrier is a large porous device that effectively reduces wind noise by disrupting and minimizing the flow near the pressure sensor, and transferring the local and direct turbulence induced noise interactions from the pressure sensor to the surface of the barrier where the sum total of the poorly correlated noise induced turbulence interactions are reduced by area averaging. In addition to effective wind noise reduction these devices maintain acoustic waveform fidelity, work in adverse conditions, and can reduce noise frequencies with associated turbulence scales sizes that are several times the size of the barrier itself. This paper will review wind barrier research conducted at the National Center for Physical. This will include a discussion on the mechanical properties of the barrier that lead to effective noise reduction including its porosity, size, shape, and number of filtering layers. Barriers designed and studied at the National Center for Physical Acoustics and by others are compared and discussed. A simple empirical model predicting wind noise reduction based on the mechanical properties of the barrier and the turbulence flow interactions located inside, on the surface, and outside of the barrier is given