WIND INDUCED ISOTHERMAL AIRFLOW PATTERNS IN A SCALE MODEL OF A NATURALLY VENTILATED SWINE BARN WITH CATHEDRAL CEILING

Abstract

The airflow patterns in naturally ventilated barns are important for the air velocity that the animals are exposedto under windy conditions. Thus animal welfare may be affected by the sidewall configuration, i.e. size and position of theventilation openings.<br><br>In order to get more knowledge of the effect of the sidewall configuration, the air velocities in the animal zone of agrowing/finishing pig house were measured in a wind tunnel. A 1/20 scale model was used for the experiments. The modelwas placed within the boundary layer of the wind tunnel. Low 3.2 m/s, medium 5.5 m/s, and high 7.5 m/s free wind speedswere applied with a corresponding roughness coefficient for the wind profile of n = 0.11, 0.18, and 0.20. Airflow patterns andair velocities in the scale model were determined with the wind perpendicular to the sidewall. There were fulllengthventilation openings in both sidewalls and no ridge opening. The experimental variables were the ventilation opening heightand the position of the ventilation openings in the sidewall.<br><br>The experiments showed that the height of the wall between the ventilation opening and the ceiling was most importantfor the airflow patterns in the building model and thus on the air velocities in the animal zone. When the inlet was flush withthe ceiling or the wall height between the ventilation opening and the ceiling was small, the supply jet attached the ceilingon entry. In this case the air velocity in the animal zone could be estimated by use of relationships between wind velocity andheight of the ventilation opening. When the wall height between the ventilation opening and the ceiling became larger thana critical value, the supply air jet attached the floor on entry. For the same outside condition and the same ventilation openingheight, the downjet resulted in considerably higher air velocities in the animal zone than the upjet.