CH-93-12-3 -- Air Velocity Characteristics in an Experimental Livestock Building with Nonisothermal Jet Ventilation PDF

Air velocity characteristics in a full-scale, climate-controlled section of a livestock building with a high ventilation rate were measured with three-dimensional ultrasonic anemometry, a new approach to indoor air velocity measurement. With simulated animal sensible heat of 151 W/m² (48 Btu/h per ft²) of floor, air jets projecting from both sides of a baffled diffuser under the peak of a gabled ceiling created nearly full, rotary air distribution patterns except for a small secondary circulation at the centre of the room. Air turbulence was dominated by frequencies between 0.1 and 1.0 Hz and Eulerian length scales between 0.2 and 0.6 m (0.7 and 2.0ft). Cross-sectional fields are presented for probability distributions of air velocity vectors and for various turbulence parameters including time and length scales. kinetic energy, energy dissipation, and microscale. A new definition for turbulence intensities and the use of irregularity factors are also introduced for describing turbulence fields in ventilated rooms.

KEYWORDS: air, speed, properties, experiment, farm animal housing, ventilation, indoor, jets, air jets, air change rate, measuring, ultrasonics, anemometers, diffusers, rotating, air distribution, turbulent flow, rooms, air flow rate, air flow.