A Fundamental Study on the Air Flow
Structure of Outflow Openings
Tomoyuki Endo1,
Takashi Kurabuchi2, Masaaki Ohba3, Yoshihiko Akamine1
and Motoyasu Kamata1
1University
of Tokyo, 2Tokyo University of Science, 3Tokyo Polytechnic
University.
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Abstract
A
Local Dynamic Similarity Model, applicable to dynamic similarity of
cross-ventilation, has been applied to outflow openings. Cross-ventilation
performance at the openings on the outflow side has been evaluated, and the
structure of air flows around the outflow openings has been studied by LES and
wind tunnel experiments. It was found that LES reproduces the wind tunnel
experiment results fairly well, such as the extensive increase of discharge
coefficient in a small region where dimensionless room pressure, PR*,
is low. The evaluation of the pressure field by LES revealed that the remainder
of the dynamic pressure in the air flows and the change of the pressure field
around the outflow openings have a strong influence on the discharge
coefficient. Furthermore, by identifying the configuration of the stream tube of
the ventilation air flow, it was found that the discharge coefficient is changed
depending on how the air flows exit. In general, dynamic pressure, Pt,
tangential to the wall surface at the outflow openings is considered to be lower
than that at the inflow side. The occurrence frequency of PR* was
investigated by a full-scale experiment, and it was elucidated that the region
of PR* where the discharge coefficient is extensively decreased
develops only very rarely.
Key words:
cross-ventilation, local dynamic similarity model, large eddy simulation, wind
tunnel experiment, discharge coefficient, outflow openings.
