Mass Flow Rate of Granular Material from an L-ValveWithout Aeration - Selected Topics of Computational and Experimental Fluid Mechanics - page 295

Fig. 5 In the pipe on the left
hand side a granular column
in the standpipe does not is
maintained because ʱ>ʸ r ,

whilst in the pipe on the
right hand side ʱ<ʸ (ʱ = r

0 . 49 rad and ʸ = 0 . 57 rad ) . r

Fig. 6 Plot of the measured
mass flow rate of beach sand
from standpipes for several
diameters as a function of
ˁ

2 D 5 / 2 . Error bars are
of 4%

1 /

g b

In experiments we used acrylic pipes 50 cm lengths and inner diameters D = 0 . 49 ,

0 94 cm, respectively. The mass flow rates were measured by

using a force sensor model Pasco CI-6537 with a resolution of 0

. 70 , 1 . 10 , 1 . 34 and 1 .

03 N . Details of the
measurement procedure are given elsewhere (Medina et al. 2014 ) (Fig. 5 ).
In Fig. 6 we show the plot of m sp , the experimentally measured mass flow rate
from vertical pipes of several diameters, as a function of

.

2 D 5 / 2 , and it yields
a linear fit for all filling heights. It means that the formula ( 2 ) is a good correlation
to describe the mass flow rate from pipes. The best fit produces a dimensionless
discharge parameter c

1 /

ˁ b g

97.
Finally, we measured the mass flow rate fromL-valves, m LV , by using beach sand.
In Fig. 7 we plot m LV versus

= 2 .

/

2 D 5 / 2 1

to prove if Eq. ( 1 ) is fulfilled. We
made two L-Valves that allowed the gravity flow: one was made with a pipe 1.94 cm

ˁ b g (ʱ − ʸ r )