In order to see the effect of width of weir b, experiments are performed for b=0.2, 0.1, 0.05, 0.025, and 0.0125 m when D=0.2 m, and for b=0.025 m when D=0.1 m. According as the magnitude b decreases, the drop of hydraulic gradient (water surface) increases. Consequently, the coefficient of discharge deviates from that of c when b is large. Then, estimating the head h
0 on the cross section at the weir plate, and recalculating c
0 using h
0, it has been found that the differences between c and c
0 remarkably decrease. Further, the author obtains an empirical formula [numerical formula] which is based on the Rehbock's formula, where Q is discharge, b is width of weir, g is gravitational acceleration, h : head ; D : the height of weir ; c : coefficient of discharge. The empirical formula can be applied to (i) b >0.60 m, 1.0 m >D >0.1m, 0.6 m >h>0.025 m, D≩h, (ii) 0.60 m≩b≩0.05 m, 0.2 m≩D≩0.1 m, D≩h>0.025 m and the head is measured at the point 1 m above the weir plate and channel is made of wood, whose surface is planed smoothly.
抄録全体を表示