Flow Passage Through
the modeled maximum valve open-
contraction coefficient at small valve
ing led to the conclusion that the
openings. However, the contraction
the Lock System
emptying valve reaches a maximum
coefficient produces accurate esti-
opening of 97 percent (b/B = 0.97).
mates of the culvert pressures at the
critical period and accurately cap-
The steady-state discharge
The automatic error-minimization
tures the lowest pressures during
through the lock filling and emptying
process that couples the lock model
the filling operation.
system is quantified with a discharge
with optimization software found the
coefficient to provide a
loss coefficients appropriate for the
head-discharge relation in the form:
emptying system components.
Emptying System
Model results for the adjusted emp-
Q = 2CdAV 2gH
(1)
tying system model are provided in
Here, Q is the discharge through
The loss coefficients associated
Figure 3. The computed emptying
the lock, Cd is the lock discharge
with the emptying system were
curve and the pressures down-
coefficient, AV is the valve area, g is
determined using the data from a
stream of the emptying valve
the gravitational acceleration, and H
single-valve emptying operation.
matched the field data well during
These runs were used to quantify
is the lock lift, which is the difference
the critical period of low pressure.
loss coefficients for the sidewall
between upper and lower pools. The
As with the filling valves, the soffit
ports acting as intakes and the
selection of valve area as represent-
pressure downstream of the empty
outlet manifolds. The field data indi-
ing the flow area is a common
valves are higher than those
cated that the emptying valve never
choice in lock design and evaluation.
observed in the prototype for valve
reached the full open position (i.e.,
Steady-state solutions were com-
openings less than 50 percent. The
b/B = 1.0, where b is the valve
puted by simulating 80 min of lock
model pressures are in reasonable
opening height and B is the culvert
operation beginning with the lock full
agreement with the field data at the
height). The data show significant
and both the filling and emptying
time in which the pressures are
head loss across the valve, when in
valves closed. First, the filling valves
lowest.
the full open position. Adjustment of
were fully opened in 83 sec. Then
Figure 3. Model validation results for single-valve-emptying operation, upper pool 221.4, lower pool 210.2
40
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