Expt No: Date:
DETERMINATION OF COEFFICIENT OF DISCHARGE AND CALIBRATION OF TRIANGULAR NOTCH AIM
i)
To find the co co-ef -efficie cient of of discha charge
ii) ii)
To cali calib brate rate the the given iven Triang iangu ular lar notc notch h.
iii) ii)
To plot th the gr graphs Cd Cd Vs Vs H, H, lo log Qa Vs log H and Q a Vs H (calibration curve)
APPARATUS
The apparatus consists of an open channel with a provision for fixing the notch to be calibrated across it. centrifugal pu!p is used to suppl" water to the channel, the #uantit" of which can be varied b" ad$usting the valve fitted to the suppl" pipe. There is a hoo% gauge to !easure the height of water passing through the notch. !easuring tan% fitted with a pie&o!eter
where, Qa is the actual discharge in ! 's, !easured b" the !easuring tan%. The calibration e#uation of the notch is given b", n
.
Qa = KH
PROCEDURE
) tart the pu!p after closing the discharge valve full". /) 0pen the valve to all the water to fill up to the sill level and note down the sill level reading using the hoo% gauge. ') 1aintain a constant level of water in the channel b" ad$usting the discharge valve. 2) +ote down the level of water b" using hoo% gauge and also note down the ti!e for 3h 4 c! rise of water in the !easuring tan%. 5) 6epeat the experi!ent for different levels of water. 7) Close the discharge valve and stop the pu!p.
Ti!e for 5c! of rise of water level in the collecting tan%, t 8 ctual discharge, Qa 8 ( 9 x)t
T'ere#ore, A$t*a %!&$'are, +a
s
8
c!'s.
-
$ /&.
I.0) $a$*at!o" o# T'eoret!$a D!&$'are, +t'
Theoretical discharge of the triangular notch is calculated using the e#uation,
Qth =
8 θ x tan ÷ x 2g x H 5/2 15 2 !'s
ngle of the triangular notch,
θ
8
:; degrees
II) Ca!0rat!o" o# tr!a"*ar "ot$' n
The calibration e#uation of the triangular notchis discharge,
Qa = KH
here K and n are constants for the triangular notch. H is
the head causing flow in centi!eters of water. 8
c!
> is the ntilog (log >) here log> is the ? intercept of the graph log Q a Vs log H 8 > 8 ntilog (log >)
8 ntilog (log ---------)
8
n is slop of the graph log Q a Vs log H 8 @"@x
.
RESULTS 2. T'e $oe##!$!e"t o# %!&$'are #or t'e !1e" Tr!a"*ar "ot$', C% 3. T'e !1e" Tr!a"*ar "ot$' !& $a!0rate% . T'e rap'& C% 4& H, o +a 4& o H a"% +a 4& H ($a!0rat!o" $*r1e)are potte%.
INFERENCE
4I4A 4OICE
) /) ') 2) 5)
hat is the difference between a notch and a wierA hat are the advantages and disadvantages of a triangular notchA hat is the use of baffle wallsA uggest an" other !ethod for the !easure!ent of discharge in open channels. hat is nappeA
O0&er1at!o"& a"% Ta0*ar Co*"
ngle of Triangular notch 8B8 :;
S! e1e rea%!", '2 -
$
rea of collecting tan% in c!/, 8 6ise of water in collecting tan% 85c! Ti!e for 5c! of Hoo% gauge Head rise of water in the reading, causing flow, collecting tan%, erial +o h/ H8 h-h/ t C! of
C! of
water
water
sec
ctual discharge
Theoretical discharge
Qa
Qth
c!'s
c!'s
log Qa
log H
/ ' 2 5 7 D verage coefficient of discharge, Cd 8
Ca$*at!o" #or $a!0rat!o" o# Tr!a"*ar "ot$' > 8 ntilog (log >)
8
ntilog (log ---------) 8
HOLY KINGS COLLEGE OF ENGG & TECH. DEPARTMENT OF MECHANICAL ENGGPage +o
C d
=
Qa Qth
n is slop of the graph log Q a Vs log H 8 @"@x 8 therefore, ctual discharge,
n
Q a K H =
Ca!0rat!o" ta0e Head in c! of water ctual discharge Qa8>Hn c!'s
HOLY KINGS COLLEGE OF ENGG & TECH. DEPARTMENT OF MECHANICAL ENGGPage +o
