Paper 1
Plane-Air-Jet Corner Zone Modelling
in a Room Ventilated by an Active Chilled Beam
Guangyu
Cao1, Jarek Kurnitski1, Mika Ruponen2,
Panu Mustakallio2 and Olli Seppänen1
1Department
of Mechanical Engineering, Helsinki University of Technology, 02150 Espoo,
Finland
2Halton
Oy, Haltonintie 1-3, 47400 Kausala, Finland
Abstract
Recent studies have
demonstrated the influence that air jets in rooms ventilated by chilled
beams have on draught-related thermal sensation. The most critical zone in
which people often suffer draught sensation is located near a wall and
close to the floor. To avoid the draught sensation, the critical
velocities of the returning air jet should be specified and determined
before the jet enters the occupied zone. In this study, the velocity of
the attached plane jet was modelled and measured at six heights and at
eight different distances from the wall. Results showed that the returning
corner airflow reattaches to the floor surface with entrained ambient air
after separation from the wall. The maximum returning air velocity was
found to be close to the floor surface. Air in the rest of the room air
was shown to move, rather than remain still. Moreover, the moving room air
does enforce free shear at the free boundary of the attached jet. This new
model could be applied to estimate the possibility of draught risk and to
predict the returning airflow velocity within the occupied zone at the
most critical corner region.
Key words: active
chilled beam, air distribution, returning-air-jet, test measurements,
numerical modelling, comparison of calculated results with measurement,
corner zone.
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