Factors Determining Air Velocity Distribution in Tunnel‐Ventilated Broiler Houses

Approximately 80% of the cooling produced in a modern tunnel‐ventilated poultry house is a result of high wind speed (500 ft/min+) moving over birds. Improvements in bird performance have been document by increasing air speeds as little as 20% in tunnel‐ventilated houses, especially when larger birds are involved. Though houses may be designed for an average air speed of 500 or 600 ft/min, air speeds across the cross‐section of house may vary 30% or more resulting in significant differences in the coolingreceived by birds positioned in different areas of the house (side wall vs center). Furthermore, air speeds are the highest at the ceiling which is farthest from the birds. Very little work has been done documenting what factors affect air velocity profiles within tunnel‐ventilated poultry houses. The objective of the current study is to determine what factors affect cross‐sectional air velocity distribution in a tunnel‐ventilated broiler house. The air velocity profiles that have been studied thus far in poultry housing measures air at one level in the house (sometimes at bird level and sometimes 3‐4 ft off the floor). The unique aspect of the current study would be to use a cross‐sectional air velocity profile to study air movement in tunnel‐ventilated poultry houses using a grid of 16 to 20 anemometers (ceiling to floor –wall to wall). Air velocity profiles will be taken in different areas of a house (i.e, pad end, center, tunnel fan end) to determine how velocity profiles change down the length of the house. The anemometers will be connected to a computer so that wind speeds can be continuously monitored as changes are made to the ventilation system. Types of changes in the ventilation system to be studied are:
1) How air velocity profiles change with increasing air velocity (400 vs 600 ft/min)

2) Effect tunnel doors have on air velocity distribution

3) Effect side wall construction and knee braces have on air velocity distribution

4) Effect baffle curtains have on air velocity distribution

5) Effect bird size has on air velocity distribution

This new method of evaluating air velocity profiles in a house has the potential to give an estimate of the total air movement capacity of the fans in a house. Currently, this can only be achieved using a FANS unit that has to measure one fan at a time taking about one hour per fan. Total air movement capacity could be used to evaluate fan and shutter maintenance as well as differences in fans in commercial settings. Applications: If the array provides air movement information comparable to the FANS unit, it is hoped that more research can be accomplished on ventilation in poultry facilities. The information from the current study would be used to educate broiler producers on possible broiler house improvements and management practices that will maximize bird cooling during hot weather. The results will also provide better understanding of the relationship between air movement and static pressure which will allow producers to make informed decisions on future upgrades or new construction

Project funded by USPAE