Center of Pressure on Vertical Fully Submerged Plate | Jameel Academy

#Jameel_Academy_Fluid Mechanics_Tests

1. University of Duhok
College of Engineering
Civil Department
Fluid Mechanics – Practical
Fluid Laboratory



A Report About :


Center of Pressure on Vertical Fully
Submerged Plate






Student Name : Jameel Masoud Jameel
Class : B
Date of Experimental : 23 / 11 / 2017
Date of Submitting : 10 / 12 / 2017
Experiment No. : 3

2. Procedure :

1) Moment of inertia, area of torroid and the distance from pivot to the
balance pan must be noted if not given. Check the straight of
apparatus and Don’t vibrate the apparatus during procedure.

2) Add water into the center of pressure's apparatus until submerge all
plate to the water.

3) Place weight to the balance pan and then fill out water by opening
drain cock until the beam level indicator stop in the middle which
is make a balance between water, weight in balance pan and
adjustable counterbalance.

4) Measure the distance from end face of torroid to the water surface
using the ruler (scale) that shown in the torroid.

5) Reaped the procedure. But just change the weight (decrease it) and
add water until the beam level indicator stop at middle and measure
the distance from end face of torroid to the water surface again .

3. Calculations and Results :


We will calculate the Center of pressure by using this formula :


( hp )actual = y – d2 ( hp )theory = h́+
IG
Ah́


Where : y=
ML
Ah́
, d2 = 20 – d1 , h́=d1 – 5


Errors % =
( hp )
theory
− ( hp )
actual
( hp )
theory
×100

Note :
A=75 cm
2
, L=27.5 cm , IG = 625 cm
4

For example : Mass = 450 gm , d1 = 15.35 cm

h́=d
1−5 =15.35−5 =��.�� ????????????
y=
ML
Ah́
=
450×27.5
75×10.35
=��.??????� ????????????
d
2=20−d
1 =20−15.35 =4.65 ????????????

Center of pressure will be :

( hp )
actual=y−d
2 =15.94−4.65 = ��.�?????? ????????????
( hp )
theory=h́+
IG
Ah́
=10.35+
625
75×10.35
=��.��� ????????????

The error between the actual pressure's center and theory in (%) is :

Errors % =
( hp )
theory − ( hp )
actual
( hp )
theory
×100 =
11.155−
11.155
×100 =−1.21%

- The minus sign in errors indicate that actual pressure center is greater than
theory pressure center.

4. Detail's Table :

No.
Mass
(gm)
d
1
(cm)
h́
(cm)
Y
(cm)
d
2
(cm)
( hp )
actual
(cm)
( hp )
theory
(cm)
Errors
%
1 450 15.35 10.35 15.94203 4.65 11.29203 11.15515 1.21
2 410 14.35 9.35 16.07843 5.65 10.42843 10.24127 1.79
3 370 13.4 8.4 16.15079 6.6 9.550794 9.392063 1.66
4 350 12.9 7.9 16.24473 7.1 9.144726 8.954852 2.08
5 300 11.65 6.65 16.54135 8.35 8.191353 7.903133 3.52
6 250 10.4 5.4 16.97531 9.6 7.375309 6.94321 5.86




The relationship between the actual pressure's center and theory is :



6
6.5
7
7.5
8
8.5
9
9.5
10
10.5
11
11.5
12
6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11 11.5
(h
p
)
theory
( h
p )
actual
Relationship between (h
p)
actual and ( h
p )
theory

5. Discussion and Conclusion :

In this test we determine the Center of pressure on vertical fully
submerged plate, and finally we got a result after doing all procedure
accuracy, which is different pressure's center with different weight. as
shown in result, with increasing weight the distance form center of
pressure to surface of water will increase and the force in the center of
pressure will be increase. in this test we calculate the center of pressure
by two methods which is actual and theory, the difference between it, is
the errors in actual measurement. we have some errors but it doesn’t
mean that our test is wrong, because every test has some errors. in our
test the maximum error in percentage is (5.86 %) which is smaller than
10%. the result will approximately or nearly to the right value which is
theory pressure's center, therefore from determining errors we can say
our test is correct. we know that if we do many tests we will get the right
average and the result will be very accuracy.

In conclusion the purpose of this test is to determine the actual center of
pressure, compare it with theory of pressure's center, the errors that we
have in actual pressure's center and how we can calculate the center of
pressure in actual. finally, we will get and determine the center of
pressure and errors, to know our test was correct or not.