On the validation of rotating bar apparatus providing an economical alternative to low-noise wind tunnel testing for the measurement of wind self-noise of outdoor acoustic metrological equipment

The physical form, construction materials and surface topography of noise monitoring equipment exposed to a windy outdoor environment will lead to noise, predominantly generated by the interactions of the physical object with turbulent fluctuations in air velocity. Reduction of self-noise by wind presents a challenge to the designer and clearly cannot be eliminated fully; hence, a measure of wind noise over the range of expected velocities of the outdoor environment is required data for correction of and thus accurate noise measurements. The ideal facilities required to perform such measurements are wind tunnels, with significant treatment of the air flow to reduce fan noise and other necessary considerations to ensure only the noise generated by the device itself is being measured. Understandably, these are large-scale, specialist installations, carrying very high costs in construction and amenities, and still high in paid access. Though no substitute for an accredited test facility, low-cost, readily-available product testing method can speedily and economically eliminate early problems in product development. We report upon the progress of performing in-house measurements of device wind-self-noise, generated due to airflow at a range of velocities typical of outdoor environments, using a range of techniques including our own rotating-bar test apparatus.