Airflow characteristics of circular ceiling diffusers
Citation
International journal on architectural science, v.1, no.2, 2000, pp. 59-67
Abstract
Circular ceiling diffusers are probably the most common types of air terminal devices used for air distribution in commercial buildings. Throw data are commonly provided in manufacturers' product catalogues. However, detailed airflow information including airflow pattern in the outlet region, jet centerline velocity decay coefficient (K value) and jet entrainment are not usually available.
This paper presents a series of detailed measurements of airflow characteristics for a vortex diffuser and two multi-cone circular diffusers. The flow patterns and turbulence characteristics in the diffuser outlet region and in the room were measured by using a three dimensional ultrasonic anemometer. In the region adjacent to the ceiling (0.08m from the ceiling), the air velocity was measured by using a hot-wire anemometer. The results show that the flow patterns in the vicinity of outlet region of the vortex diffuser are three dimensional and highly turbulent. Also, inappropriate design of the multi-cone circular diffuser results in "dumping" of the supply air to the occupied region of the room. The K values of the vortex diffuser investigated are in the range of 2.1 to 2.3. For the multi-cone circular diffusers, the K values cover a large range and are related to the design of the geometry of the diffuser. These detailed measurements are useful for evaluating numerical simulation models as well as for understanding the behavior of room air motion created by different diffusers.
(1) Introduction
(2) Description of experiments
(3) Results and discussion
(a) Cases of three-cone circular diffuser
(b) Cases of six-cone circular diffuser
(c) Cases of Vortex diffuser
(d) K values
(4) Conclusions
(5) Acknowledgement
(6) References
Description
Notes: Ventilation
Subject
Type
Article
Format
Date
2000
Language
en