Atsuo Ikeguchi

A Wind Tunnel Study of Natural Ventilation for Multi-Span Greenhouse Scale Models Using Two-Dimensional Particle Image Velocimetry (PIV)

A two–dimensional particle image velocimetry (PIV) system installed in a large–sized wind tunnel was used to examine the natural ventilation of fully open roof and Venlo–type multi–span greenhouses. Since the PIV system has rarely been used for large–scale, low–turbulence airflow conditions, the PIV system was investigated to improve its performance and accuracy. The PIV accuracy tests were conducted without any greenhouse models in the wind tunnel because it was very difficult to insert the anemometer sensors in the small–scale greenhouse models, and it was also assumed that the sensor itself could affect natural airflow patterns inside the models. Good results were obtained in the PIV accuracy test, and the errors were shown to be mostly in the .5% range. Additionally, the natural airflow in 2– to 10–span greenhouses was investigated using the PIV system. The PIV results indicated that the PIV technique was an effective method for evaluating the relative performance of alternative designs of greenhouse and other structures with turbulent interior air distributions.

Feeding Behaviors of Laying Hens With or Without Beak Trimming

This study quantifies feeding behavior of W-36 White Leghorn laying hens (77 to 80 weeks old) as influenced by the management practice of beak trimming. The feeding behavior was characterized using a newly developed measurement system and computational algorithm. Non-trimmed (NT) and beak-trimmed (BT) hens showed similar daily feed intake and meal size. However, the BT hens tended to spend longer time feeding (3.3 vs. 2.0 h/d, P < 0.01), which coincided with their slower ingestion rate of 0.43 g/min-kg0.75 vs. 0.79 g/min-kg0.75 for the NT counterparts (P < 0.05). The BT hens had shorter time intervals between meals (101 s vs. 151 s, P < 0.01). Selective feeding, as demonstrated by larger feed particles apparent in the leftover feed, was noted for the BT hens. The leftover feed had a lower crude protein/adjusted crude protein content for the BT birds than that for the NT birds (16.7% vs. 18.7%, P < 0.05). In addition, the leftover feed of the BT birds had lower contents in phosphorus, magnesium, potassium, zinc, and manganese (P < 0.05), although no significant differences were detected in calcium, sodium, or metabolic energy content. Baseline feeding behavior data of this nature may help quantify and ensure the welfare of animals through exercising proper engineering design and/or management considerations.

WINDWARD WINDBREAK EFFECTS ON AIRFLOW IN AND AROUND A SCALE MODEL OF A NATURALLY VENTILATED PIG BARN

Wind tunnel tests of 1:20–scale windbreak models placed in a windward position from naturally ventilated pig barns were performed to examine the capability of windbreaks to trap air contaminants emitted from livestock buildings. The airflow surrounding the windbreak and the building was measured. Dispersion of air contaminants was predicted with the proposed parameters PU, PV, and PW, which are related to airflow momentum in the leeward direction and to horizontal and vertical plume sizes, respectively. Windbreaks included a solid wall, a net screen, and another pig barn. With a solid wall as a windbreak, air emitted from the building was exhausted in the windward direction. Compared to a net screen or another barn, the solid wall resulted in the lowest airflow momentum. A high–concentration odorous area was predicted to be located between the windbreak and the building. Sprinklers in this area could possibly trap the air contaminants. When a building was placed in the windward position as a wind barrier, the dispersion of odorous air behind the leeward building was predicted to be the smallest compared to a solid wall and a net; moreover, a smaller plume width was seen. When a net screen was used, the airflow between the wall and the building moved only in the leeward direction.

Wind Induced Isothermal Airflow Patterns in a Scale Model of a Naturally Ventilated Swine Barn with Cathedral Ceiling

The airflow patterns in naturally ventilated barns are important for the air velocity that the animals are exposed to under windy conditions. Thus animal welfare may be affected by the sidewall configuration, i.e. size and position of the ventilation openings. In order to get more knowledge of the effect of the sidewall configuration, the air velocities in the animal zone of a growing/finishing pig house were measured in a wind tunnel. A 1/20 scale model was used for the experiments. The model was 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 speeds were applied with a corresponding roughness coefficient for the wind profile of n = 0.11, 0.18, and 0.20. Airflow patterns and air velocities in the scale model were determined with the wind perpendicular to the sidewall. There were full–length ventilation openings in both sidewalls and no ridge opening. The experimental variables were the ventilation opening height and the position of the ventilation openings in the sidewall. The experiments showed that the height of the wall between the ventilation opening and the ceiling was most important for the airflow patterns in the building model and thus on the air velocities in the animal zone. When the inlet was flush with the ceiling or the wall height between the ventilation opening and the ceiling was small, the supply jet attached the ceiling on entry. In this case the air velocity in the animal zone could be estimated by use of relationships between wind velocity and height of the ventilation opening. When the wall height between the ventilation opening and the ceiling became larger than a critical value, the supply air jet attached the floor on entry. For the same outside condition and the same ventilation opening height, the down–jet resulted in considerably higher air velocities in the animal zone than the up–jet.

FIELD EVALUATION OF A SPRINKLING SYSTEM FOR COOLING COMMERCIAL LAYING HENS IN IOWA

An economical, low–pressure (276 kPa, 40 psi) sprinkling system was tested for its efficacy of cooling laying hens in a commercial high–rise layer house [14 U 130 m (46 U 426 ft)] in Iowa. The sprinklers, rated at 2.1 mL/s (2 gal/h) each, were equally spaced at 3 m (10 ft) apart and 2.4 m (8 ft) above the floor in each cage aisle of the layer house. They were controlled to operate 10 s every 10 min when the inside temperature exceeded 32 _ C (90 _ F). The system was shown to improve egg production by 2.6% overall and 5.6% for the top deck (P < 0.01). There was no sign of sprinkling damage to eggshell integrity. Autocorrelation analysis has the potential to quantify the impact of heat stress history on subsequent egg production response of the hen. Work is needed to optimize the layout of the sprinklers for uniform water distribution and water application rate as a function of environmental conditions.

Mass transfer of moisture and ammonia from manure and manure litter mixture in free-stall housing

Mass transfer coefficients of moisture at the surface of pure waste, and a mixture of waste and litter were obtained from wind tunnel tests quantify moisture movement from surface of free-stall barn with high moisture. The mass transfer coefficients were expressed as a function of air velocity. Mass transfer of coexistent convection was then examined. Mass transfer of moisture from the waste and litter mixture was found to be larger than that from pure waste. It was also found that mixing litter with waste contributed to the removal of moisture from the floor surface by airflow. The surface temperature of waste or waste litter considerably affected the rate of moisture removal. Mass transfer coefficients of ammonia and an equation for ammonia generation rates from floor surfaces were likewise obtained from dimensionless numbers and wind tunnel tests.

A CASE STUDY OF DRYING WET FLOORS WITH MIXING FANS IN FREE–STALL DAIRY HOUSING

The effectiveness of mixing fans installed under the ceilings of free–stall dairy housing was evaluated as a method to dry a high–moisture manure litter mixture on the floors. The fan installation options were fan tilting angles of 45., 90. (horizontal), or no fan. The litter materials tested on the floor were recycled compost and sawdust or chopped wheat straw whose initial average moisture contents on a wet basis were 44%, 17.5%, and 5.4%, respectively. It was found that fans tilted at a 45. angle dried the floor better than fans installed horizontally or the drying obtained without mechanical ventilation. The effect of tilting fans on removing moisture from the house was about 5 times larger than horizontal installations and 30 times larger than without mechanical ventilation. The moisture content of the floor was reduced to less than 70% for a fan tilt angle of 45.. Tilting fans not only dried the floors better, but also improved the air exchange rate, reducing aerial NH3 concentrations.

PROGRESSIVE FEEDING BEHAVIORS OF PULLETS WITH OR WITHOUT BEAK TRIMMING

This study quantifies feeding behavior of W-98 White Leghorn pullets (1-3 weeks old) as influenced by the management practice of beak trimming. The feeding behavior was characterized using a newly developed measurement system and computational algorithm. Beak trimmed (BT) pullets and non-trimmed (NT) pullets exhibited significantly different eating behavior over the ages of 8 to 21 days with regard to meal size and meal duration. Beak-trimmed birds tended to eat larger and longer meals, although the differences between the BT and NT birds were not constant with age (significant interaction between beak type and age, P<0.05). No significant differences across beak types or ages were detected for ingestion rate or interval between meals. The BT and NT pullets had similar amount of daily feeding time (1.1 - 1.2 hr/day). However, the number of meals per day differed, 28 meals/day for the BT pullets vs. 35 meals/day for the NT pullets. Baseline feeding behavior information of this nature may help better quantify and ensure welfare of the animals through exercising proper engineering design or management considerations.

Feeding Behaviors of Laying Hens with or without Beak Trimming

This study quantifies feeding behavior of the W-36 White Leghorn laying hen (77-80 weeks old) as influenced by the management practice of beak trimming. The feeding behavior is characterized by a newly developed measurement system and computational algorithm. Nontrimmed (NT) and beak trimmed (BT) birds showed similar meal size. BT birds spent longer time at the feeder, which is compatible to their slower ingestion rate of 0.9 g/min vs. 1.3 g/min of the NT type. Compared with NT bird, the BT bird had smaller time intervals between meals, 200 vs. 450 s. By scientifically characterizing the feeding behavior of laying hens, baseline information will result that may help better quantify the welfare of birds.

Effects of Buoyancy and Wind Direction on Airflow and Temperature Distribution in a Naturally Ventilated, Single-Span Greenhouse using a Wind Tunnel

Experiments were performed in a wind tunnel to study the effects of buoyancy and wind direction on airflow patterns and temperature distribution within an empty, naturally ventilated, arched-roof, single-span greenhouse (open roof, open screened sidewalls). Archimedes Number was used for similarity to determine the necessary wind tunnel air speed and greenhouse floor-tooutside air temperature difference (T) for the 1/15 scale model. Buoyancy effects were studied for three T (10, 20, 30iAEC) and two wind directions (90iAE, 270iAE). Particle Image Velocimetry (PIV) was used to measure airflow vectors. Dimensionless velocity [U(x), V(x)] and dimensionless temperature (¥eT) were analyzed. At 90iAE (roof opening facing wind), the velocity of the downward flowing air from the roof (V = -0.232) created a strong circular airflow pattern that caused the influx of air through the windward sidewall to be significantly small (U = 0.06). At 270iAE (roof opening opposite to wind direction), the velocity of air entering the windward sidewall (U=0.158) was greater than from the roof (V=0.010), creating a more horizontal airflow pattern. Although there was no significant difference in the mean ¥eT inside the greenhouse model based on wind direction, the center and leeward sections were significantly greater for the 270iAE wind direction (p<0.001). Also, T did not have a significant effect on mean ¥eT inside the model. ¥eT was significantly lower at the windward side of the model for all treatments. For the 90iAE wind direction, the center of the model had the significantly highest mean ¥eT. For 270iAE wind direction the center and leeward sections were significantly higher than the windward side. Although the floor was heated, the highest temperatures were observed in the middle of the model, where airflow was minimal. If insect screens had a coarser mesh, more air could enter through the sidewalls to cool the center zone. Results from this experiment will be used to study positions for high-pressure fog cooling nozzles in the full-scale greenhouse.