Experiment No.1 Flow through a sluice gate g ate The discharge coefficient of sluice gates in free and submerged conditions plays an important role in determining the flow rate past such structures. The effects of relative gate gate open openin ing g and and subm submer erge genc ncee ratio ratio have have been been wide widely ly cons consid idere ered d by severa severall investigators, mainly based on experimental work. Most of this work, however, lacks an analytical approach to include include the variation of discharge discharge coefficient coefficient as influenced influenced by gate opening and submergence ratio. This paper, using energy and momentum conservation theory, presents an analytical method to determine the contraction ratio and discharge coefficient of sluice gates under free and submerged flow conditions. Based on suggested relationships for the contraction ratio, variations in energy loss under free and submerged submerged flow and the submergence submergence limit are determined determined and some graphical demonstrations are adapted. The results are compared with experimental data reported by several investigators and show good agreement.
1.Objective 1.1 To study the behavior of flow though though a sluice gate in various conditions 1.2 To study the oefficient of discharge !d " 1.# To construct the alibration curves of sluice gate.
2. Experimental apparatus The experimental apparatus for this experiment consists of rectangular flume with the sluice gate inside, depth gauge, and stop watch.
Figure1 $ectangular flume with sluice gate
Figure2 %epth gauge
3. Theory &luice gate are used for flow control and discharge measurement. 'ressure at water surface is atmospheric or (ero gage pressure )ater surface * pie(ometric head level. i.e. level registered by manometer with a pie(ometric tap +pen channel flow, in general, has two possible flow depths for each energy level &ubcritical and supercritical &luice gate changes flow from subcritical to supercritical.
Figure3 -low under sluice gate !$oberson, ohn / layton rowe,100"
ike -low Through +rifice minimum cross3sectional area !vena contracta" is slightly downstream from the gate
4deal -low Theory !5o 6nergy osses" Q = V × A1
!1" 6xperimental &tudies discharge coefficient -low is never really 7ideal8 . oefficient is related to relative si(e of gate opening Brater/9ing summari(e some of these general from 2 g×dH
¿ ¿
:*
!2"
C× A× ¿
&pecific energy energy in an open channel measured relative to the channel bottom 2 V 6 * y + 2 g !#" -or two values of y with the same value of 6 2 2 V 1 V 1 6 * y 1+ 2 g * y 1+ 2 g
!;"
ombine this with the continuity e
− y + E y 3
Q
2
*
2
2qb
2
!@" The subcritical and supercritical flows are two of the three areas for the solution. The third area of the solution has a negative value of y, which is meaningless for open channel flow. !Aenderson 10??"
Figure raph is shown relationship between specific energy and flow depth !$oberson, ohn / layton rowe,100"
&luice gate experiment study the application of one3dimensional flow analysis involving continuity, energy and momentum es stated, there are two flow depths, subcritical and supercritical, for each energy level. The easiest approach is to compare the measured values of y2 with values computed for observed y 1 -orce By Momentum 6
*
γ × V x
×Q
!D" Becomes 1
F g
*
Q× ( V 1−V 2 ) + b ( y 1− y 2 ) 2
2
2
γ ¿
!0" )here E * density of water g !in the drawing" * gravity constant : * flow rate v1,y1 * upstream velocity and depth v2,y2 * downstream velocity and depth b * width of rectangular channel
Figure! -orce by Momentum 6
3.1 Free Flow con"itions This condition is the flow which is freely Fet flow through the sluice gate without compression and the surface contact with atmosphere so, the water surface has the pressure e
Figure# -ree flow conditions !Thompson 10DH Thompson and )arsi 10D2H Masliyah et al. 10D=".
$ena contracta Figure% -ree flow conditions !Gena contracta"
3.2 &ubmerge" Flow 'on"itions This condition, the water flow through a gate and itIs compressed by water at downstream and submerged under the surface. The submergence is called Gortex or 6ddy currentH is the swirling of a fluid and the reverse current created when the fluid flows past an obstacle. The moving fluid creates a space devoid of downstream3 flowing fluid on the downstream side of the obFect. -luid behind the obstacle flows into the void creating a swirl of fluid on each edge of the obstacle, followed by a short reverse flow of fluid behind the obstacle flowing upstream, toward the back of the obstacle. This phenomenon is most visible behind large emergent rocks in swift3 flowing rivers. This flow has energy losses.
Figure( &ubmerged flow condition !Thompson 10DH Thompson and )arsi 10D2H Masliyah et al. 10D=".
E""y current Figure) &ubmerged flow condition !6ddy current"
3.3 *asic e+uation BernoulliIs 6
velocity → discharge, :, :*>G Q1
Q2
A1
A2
¿ ¿ ¿2 ¿ Z 1 +¿
¿ ¿ ¿2 ¿ Z 2 +¿
*
Q1
Q2
A 1
A 2
¿ ¿ ¿2 ¿ y 1+ ¿
¿ ¿ ¿2 ¿ y 2+ ¿
*
!11"
!12"
q=
unit discharge,
Q B
-rom !#.1" , 2
2
q − q 2 2 2 g y1 2 g y 2 2
q 2g ¿
1
"!
2
y 1
y 2− y 1
*
− 1 ¿
y 2− y 1
*
2
y 2
!1#"
!1;" 2
2
q 2g
2
y 2 − y 1
)(
¿
2
2
y 1 y 2
¿
y 2− y 1
*
!1=" 2
q 2g ¿
( y + y ) ( y − y ) 2
)(
1
2
2
1
1
y 1 y 2
¿ =
y 2− y 1
(16)
q
( y y ) × ( y − y ) × 2 g
2
*
2
2
1
2
2
2
( y + y ) ( y − y ) 2
1
2
1
!1@" q
( y y
2
*
2
2
1
2
×2 g )
( y + y ) 2
1
!1D"
:*
√ y
2 1
2
y 2 × 2 g
y 2 + y 1
:*
y 1 y 2 √ 2 g y 2+ y 1
:*
C d W √ 2 g y 1
!10"
!21"
!2"
d * oefficient of discharge q ( actual ) q ( theory ) * d
¿ 1
!22" C d
q W √ 2 g y1
*
BernoulliIs 6
2
V y 1+ 2g
V y 2+ 2g
*
2
q y 1+ 2 g y1
!2#"
2
q y 2+ 2 g y1
*
!2;"
Momentum 6
y 2 2
!2=" 2
2
y 3
q + g y 2 *
2
2
q + g y3
!2?"
-ree -low :*
C } rsub {d} W sqrt {2g {y} rsub {1}} ¿
!2@"
&ubmerged -low <*
C d W √ 2 g y 1
!2D"
Experiment -roce"ure ;.1 +pen the sluice gate for 1= mm. ;.2 Turn on the water pump and then open the valve. ;.# )ait until the water level does not change, measure the water depth y 1 and y 2 for a free flow.
Figure1 Measure the water depth y1 and y 2
;.; Measure the discharge by using the notched3weir downstream of the basin. Cse the e
Figure11 %ischarge by using the notched3weir downstream of the basin
;.= >dFust the weir on the downstream of the flume until the 6ddy current is occurred downstream of the gate. )ait until the water level does not change, measure the water depth y1 and y# for a submerge flow.
Figure12 6ddy current
;.? >dFust the weir to get the different # more point of y 1 and y#. ;.@ 4ncrease the water discharge by adFusting the valve. $epeat the step number ;.#3 ;.? again. Cse totally ; discharges. ;.D +pen the sluice gate about 2= mm.
;.0 $epeat the step number #3@ again.
Figure13 )eir gets the different # more point of y1 and y#
