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Reduced-scale modeling of a freestanding exhaust hood.
Mead K; Johnson D; Esmen N; Phillips M
American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California. Fairfax, VA: American Industrial Hygiene Association, 2002 Jun; :25-26
Local Exhaust Ventilation (LEV) design equations do not normally account for worker presence, varying cross-drafts, or turbulence. In recognition, the American Society of Heating, Refrigerating and Air-Conditioning Engineers recommends both fluid dynamic (dynamic similitude scale modeling) and computerized modeling as valuable tools in LEV hood design. Unfortunately, computer modeling often requires assumptions that without experimental verification, result in uncertainty. While similitude modeling is a recognized research tool throughout fluid mechanics, it's historically ignored in industrial ventilation. When it is applied, the modeled streamlines tend to be "uniform" like those within a large booth as opposed to the converging streamlines inherent with freestanding hoods. The subject research investigated similitude modeling as a research tool for industrial ventilation design then used the model to evaluate effect of worker presence upon LEV hood performance. The research scope was limited to a reduced-scale, water model of a freestanding flanged circular hood (FCH). A glass aquarium was the "room" and a pump the "fan" for the model. Measured capture velocities induced by the FCH were remarkably consistent with ACGIH design equation predictions.
Models; Exhaust-hoods; Ventilation; Computer-models; Workers; Models; Mathematical-models; Ventilation-systems
American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California
OH; OK; CA
Page last reviewed: May 5, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division