Abstract:
Regulator may defined as a hydraulic structure consists of piers at regular intervals
arc generally constructed across the channel to control the flow. These structures an:
capable of both draining out water from the catchment and entering water from
riverside.
In Bangladesh, Bangladcsh Water Development Board [s the Governmcnt
Organization mostly responsible to build these kind of hydraulic structure for
irrigation, flood control and drainage. Khulna-Jessore Drainage Rehabilitation Project
is one of the large projects of BWDB having 20 drainage regulators consist of 2-21
vents. These regulators were constructed mainly on the basis of the head discharge
relationship obtained from the theoretical equations. Proper operation and
performance of these regulators can be ensured with accurate head-discharge
relationsllip. As the co-efficient of contraction plays a sensitive role in computation of
discharge, drainage may vary signif~cantly from the actual discharge in case of poorly
judged contraction values. In this regard head-discharge relation was developed
through a scale model of Sholmari regulator which is to constructed. Also the effect
of gate weight in head-discharge has been investigated.
With the model of Sholmari regulator a total of sixty-four test runs were constructed
for different gate weights and discharges in the Hydraulics and River Engineering
laboratory, WRE, BUET. The f1ume was calibrated with respect to a rehbock weIr
placed at the tail end of the flume before the experiment was started.
Head-loss discharge relationship for different weight of flap has been developed.
From the analysis it has been found the experimental result significantly differ from
the theoretical results. To have good matching of the computed results with the
theoretical results some modifications have been proposed. These modifications are
proposed in contraction of co-efficient as well as in area computation. The proposed
values of co-efficient of contractions are ~l2= 0.70 and ~l4 = 1-0.20 cos<p instead of ~l2
= 0.5~ - 0.70 and )..1-4= 1-0.35 cos<p respectively. In area computation As = 1.5 Aycnt is
proposed instead of As = 2 Aycnt. The measured discharges were found to vary within
the range of 12% to 23% than the theoretical discharges. But with the proposed
modified equation discharge were found to vary within the range of 0.16% to 6.3%.
