Masaaki Ohba, Takashi Kurabuchi, Tomoyuki Endo, Yoshihiko Akamine, Motoyasu Kamata, Aya Kurahashi
Bibliographic info:
The International Journal of Ventilation, Vol. 2 N°4, March 2004, pp 383-393, 27 Fig., 2 Tab.,6 Ref.

The proposed local dynamic similarity model of cross-ventilation predicted ventilation flow rates more accurately than the conventional orifice flow model assuming constant discharge coefficients when discharge coefficients actually decreased with change of wind direction. This model was used to develop a new method for evaluating the ventilation performance of window openings. The obstructive effect of model size on flow fields in a wind tunnel was avoided by installing the opening parallel to the wind tunnel floor. The ventilation performance for various types of inflow openings was assessed by the ventilation performance evaluation system. The discharge coefficient was expressed by an approximate expression using dimensionless room pressure PR*. A ventilation performance database was thus produced. For the field experiment in a full-sized house, it was found that about 60% of all wind data were in the range of |PR*| < 5.

This reveals that the discharge coefficient decreases frequently in actual wind.