How do you model THAT?!?: Louvered structures, high air speeds, infrasound, and temperature gradients

This presentation will discuss two case studies on noise emissions from various industrial machinery. The first case study will discuss noise emissions from a proposed multi-story underground urban electrical substation with an at-grade park, surrounded by noise sensitive uses. Substation noise sources include various electrical and mechanical equipment, which communicate with the exterior via ductwork leading to large supply and exhaust air shafts, which connect to at-grade louvered structures. Noise emissions were evaluated for code compliance at within park areas and nearby receptors. Design challenges included large duct dimensions, extremely high air velocities in shafts, significant self-noise contributions from large silencer banks, and short distances to noise sensitive receptors. The second case study will discuss an investigation into a noise complaint directed at a natural gas station, primarily during winter months. Station noise sources included underground valves and natural gas burners. The investigation revealed that noise produced by station burners contained significant tonal and infrasonic components that fluctuated significantly over short durations. Due to the prevailing season, significant temperature gradients between air from the burner exhaust stacks and ambient temperatures complicated analyses.