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An accurate measurement of the airflow rate in a naturally ventilated animal house is still an issue due to the large uncertainties of the available techniques. These uncertainties are mainly related to the variability of the velocity profile in a naturally ventilated opening caused by, among others, fluctuations in wind
direction and speed. An experimental set-up was built to develop airflow rate measurement methods which can cope with these different profiles and can be further developed for future use in naturally ventilated openings. The methods were compared to a reference technique for mechanical ventilation (VDI2041) as no such reference exists for natural airflows. A relative measurement error from this reference of max. 10% was deemed acceptable. The methods were based on a fully automated traverse movement of respectively a 2D and a 3D ultrasonic anemometer behind the outlet of two different rectangular ducts (respectively
1 m and 3 m wide). Several airflow rates were imposed, combined with disturbances of the airflow to obtain different velocity profiles. Measurements performed with a 2D ultrasonic anemometer gave rise to relatively high measurement errors (up to 18%) related to the 3D character of the outflow jet. Two methods were developed with a 3D ultrasonic sensor in order to capture the outflow characteristics more adequately. The Basic method concentrated on the area in front of the outlet, while an Extended method paid more attention to the airflow around the edges of the outlet. Both methods succeeded in keeping the
relative measurement error below the 10% limit, and even below 5% error for the 3 m wide duct. For future use in naturally ventilated openings, more research is necessary to further adapt the methods to continuously changing conditions of wind speed and direction.
Vertaalde titel van de bijdrageOntwikkeling van een referentiemethode voor luchtdebiet metingen door rechthoekige openingen naar toepassing in natuurlijk geventileerde stallen: Deel 2: Geautomatiseerde 3D-benadering
Originele taal-2Engels
TijdschriftComputers and Electronics in Agriculture
Volume106
Pagina's (van-tot)20-30
Aantal pagina's11
ISSN0168-1699
StatusGepubliceerd - 14-mei-2014

ID: 2861916