1965 年 1965 巻 118 号 p. 328-336
This paper deals with results of tests made on the following matters.
(1) The flow through the rectangular orifice fitted on a rectangular air duct.
(2) The divided flow at the tee branch for a circular air duct.
As the results of expeiments, the following empirical formulae have been obtained
(1) Coefficient of resistance at the rectangular orifice.
ζ= (Ad/αA0-1) 2
α=0.625+0.375 (A0/Ad) 3
(2) Loss in the divided flow at the tee branch for a circular air duct.
Main duct P=0.05 Hm 0.6 S2Hm
Branch duct P=0.99 Hm+0.341 Hb
ζ=coefficient of resistance
A0=sectional area of orifice
Ad=sectional area of duct
P=pressure loss, mmAq
Hm=velocity head in the main duct, mmAq
Hb=velocity head in the branch duct, mmAq
S=flow quantity ratio