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Airflow Patterns Related to Polluted Air Dispersion in Open Free-Stall Dairy Houses with Different Roof Shapes

Ikeguchi, A., Okushima, L.
Transactions of the ASAE 2001 v.44 no.6 pp. 1797-1805
air, air flow, free stalls, models, momentum, wind direction, wind tunnels
One-thirtieth scale models of naturally ventilated free-stall dairy houses were tested in a wind tunnel to investigate the relationship between roof type (open-ridge, semi-monitor, mono-slope), roof slope angle (16.7 ° , 18.4 ° ), and wind direction and air movement inside and outside the house. Dispersion properties of gaseous contaminants from the house were predicted from these air movement results. A proposed parameter, P U , was developed with respect to airflow momentum and airflow vectors showing that the open-ridge house had characteristics to easily transfer contaminants from inside to outside and to increase dispersion at the leeward side. It was predicted that the mono-slope type might decrease contaminant transport and create a high concentration area near the leeward side of the building. When the open side of the semi-monitor type ridge faced windward, contaminants dispersed more readily than when the ridge faced leeward. In addition, a small difference in slope angle made a large difference in air movement and contaminant diffusion of open-ridge houses.