Paper 8: Volume 5 No.1 June 2006 Edition
Flow Visualization and Inflow Direction Measurement at
a Cross-Ventilated Large Opening
Hisashi
Kotani and Toshio Yamanaka
Department
of Architectural Engineering, Graduate
School
of
Engineering
,
Osaka
University
,
Suita
565-0871
Osaka
,
Japan
Abstract
In the case of cross
ventilation through a large opening, it is well known that the inflow
direction at the opening is not normal to the opening. A simplified
prediction method for simultaneously predicting the inflow direction at
the inlet opening and the airflow rate is presented. It is also well known
that the use of general discharge coefficient values (CD) is
not suitable for the calculation of cross ventilation rate. The first
reason is that the simple connection of the pressure loss coefficient of
an opening (z as the reciprocal of
square CD) in series, under-estimates the airflow rate.
Secondly, CD varies according to the wind direction and the use
of normal values over-estimates the airflow rate. Therefore, the proposed
method uses the total pressure loss coefficient of the room (x)
instead of z (or CD).
Flow visualization was conducted under various conditions using a simple
room model and showed the basic flow characteristics at the inlet opening.
Wind tunnel tests using a three-storey apartment building model with a
movable test room were conducted to investigate the inflow direction and
the airflow rate. The combination of room positions and external wind
directions results in various inflow directions at the inlet opening.
Key words: cross
ventilation, airflow rate prediction, inflow direction, wind tunnel test,
room model, comparisons of calculation with measurement, apartment
building.
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