exp 6 hydrostatic pressure

8/17/2019 Exp 6 Hydrostatic Pressure

1/15

FACULTY: ENGINEERING

TECHNOLOGY

EDITION:

LABORATORY: FLUID

MECHANICSREVISION NO:

EXPERIMENT: HYDROSTATIC

PRESSURE TEST

EFFECTIVE DATE: 1/3/2014

AMENDMENT

DATE:

FACULTY OF ENGINEERING TECHNOLOGY

DEPARTMENT OF CHEMICAL ENGINEERING TECHNOLOGY

FLUID MECHANICS LABORATORY

LABORATORY INSTRUCTION SHEETS

COURSE CODE BNQ 10304

EXPERIMENT NO. EXPERIMENT 6

EXPERIMENT TITLE HYDROSTATIC PRESSURE TEST

DATE

GROUP NO.

LECTURER/INSTRUCTOR/

TUTOR

1)

2)

DATE OF REPORTSUBMISSION

DISTRIBUTION OF MARKS

FOR LABORATORY

REPORT:

ATTENDANCE/PARTICIPATION/DISCIPLINE: /5%

INTRODUCTION: /5%

PROCEDURE: /5%

RESULTS& CALCULATIONS /15%

ANALYSIS /15%

DISCUSSIONS: /20%

ADDITIONAL QUESTIONS /15%

CONCLUSION /10%

SUGGESTIONS& RECOMENDATIONS /5%

REFERENCES: /5%

TOTAL: /100%

EXAMINER COMMENTS: RECEIVED DATE AND STAMP:


2/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

KOD ETIKA PELAJAR

(KEP)

JABATAN TEKNOLOGI KEJURUTERAAN KIMIA

FAKULTI TEKNOLOGI KEJURUTERAAN

Saya dengan ini mengaku bahawa saya telah menyediakan laporan ini dengan daya usaha

saya sendiri. Saya juga mengaku tidak menerima atau memberi sebarang bantuan dalam

menyediakan laporan ini dan membuat ikrar ini dengan kepercayaan bahawa apa-apa yang

tersebut di dalamnya adalah benar.

Ketua

Kumpulan

Nama:

No. Matriks:

(Tandatangan)

Ahli 1 Nama:

No. Matriks:

(Tandatangan)

Ahli 2 Nama:

No. Matriks:

(Tandatangan)

Ahli 3 Nama:

No. Matriks:

(Tandatangan)


3/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

1.0 OBJECTIVES

1. To determine the centre of pressure on both submerged and partially submerged plane surface.2. To compare the centre of pressure between experimental and theoretical.

2.0 LEARNING OUTCOMES

Demonstrate the ability to conduct experiments related to fluid flow by following standard operating

procedure effectively in a group.


4/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

3.0 INTRODUCTION / THEORY

The hydrostatic pressure apparatus has been designed to study on the hydrostatic of an object immersed in fluid. It will enablestudents to measure the static thrust exerted by a fluid on a submerged surface while allowing them to compare the magnitudeand direction of the force with theory.

The calculation of the magnitude, direction and line of the hydrostatic forces exerted by a fluid on a submerged plane surface isimportant in the design of structures such as drams, bulkheads, gates, tanks, submarines etc. The pressure which the forceacting over a unit surface area and varies linearly with depth. This fact enables us to describe the pressure distribution over asubmerged surface. hen the pressure is uniform over a surface, such as static pressure on a hori!ontal surface, the resultant

force is e"ual to area times the pressure and acts through the centroid of the area. #owever, in many cases, such as li"uidsacting on a non$hori!ontal surface, the situation is more complex. % general approach has been developed to estimate resultantforce and its line of action.

In this experiment, the reliability of this approach is examined by comparing analytical values for forces and moments actingon a plane surface with experimental measurements of these values on the same surface on a partially submerged and fullysubmerged plane surface, but for more clearly to get the result of the concept

3.1 Hydros!"# $or#%s O& '(!&% S)r*!#%

&onsider a plane surface of arbitrary shape and orientation submerged in a static fluid as shown in 'igure 1. If ( representsthe local pressure at any point on the surface and h represents the depth of fluid above any point on the surface, from the

basic physics, we can easily show that the net hydrostatic force on a plane surface is given by)

∫ = A

PdAF

*1+

$"+)r% 1, Hydros!"# 'r%ss)r% o& '(!&% S)r*!#%

The hydrostatic force on one side of a plane surface submerged in a static fluid e"uals to the product of the fluid pressure atthe centroid of the surface times the surface area in contact with the fluid. Thus, basic physics says that the hydrostatic forceis a distributed load e"ual to the integral of the local pressure force over the area. (ressure acts normal to a surface,therefore the direction of the resultant force will always be normal to the surface.

In most cases, since it is the net hydrostatic force that is desired and the contribution of atmospheric pressure ( a will act onboth sides of a surface, the result of atmospheric pressure (a will cancel and the net force is obtained by)

AhgF cg ρ =*2+

APF cg= *+


5/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

(cg is now the gauge pressure at the centroid of the area in contact with the fluid. Therefore, to obtain the net hydrostaticforce, ' on a plane surface,

1. -etermine depth of centroid, hcg for the area in contact with the fluid

2. -etermine the gauge pressure at the centroid (cg. &alculate ' (cg%

%ppendix & shows the centroid and other geometric properties of several areas. The effective point of application of force which is normally called the /&enter of (ressure, &(0 of the hydrostatic force and this is not necessary the same as thecentroid.

The location of the resultant force is determined by integrating the moment of the distributed fluid load on the surface abouteach axis and e"uating this to the moment of the resultant force about that axis. Therefore, for the moment about the y axis)

∫ = A

cp dAP y y F

*+

%pplying a procedure similar to that used previously to determine the resultant force, we obtain)

0≤−= AP

IgY

cg

xx cp

θ ρ sin

*+

here, Ixx is defined as the 3oment of Inertia, or

∫ = areatheof moment I nd xx 2 *4+Therefore, the resultant force will always act at a distance y cp below the centroid of the surface *except for the special case

of sin5 6+. (roceeding in a similar manner for the x location, and defining I xy product of inertia, we obtain)

AP

Ig X

cg

xy

cp

θ ρ sin−=

*7+

here 8cp can be either positive or negative since I xy can be either positive or negative. 'or areas with a vertical plane ofsymmetry through the centroid, the y$axis *e.g. s"uares, circles, isosceles triangles, etc.+, the center of pressure is locateddirectly below the centroid along the plane of symmetry, 8cp 6.

'or most problems where we have a single, homogeneous fluid and the surface pressure is at atmospheric, the fluid specific

weight γ cancels in the e"uation for 9cp and 8cp and we have the following simplified expressions)

Ah

IY

cg

xx cp

θ sin−=

*:+

Ah

gI X

cg

xy

cp

θ sin−=

*;+


6/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

3.2 Hydros!"# 'r%ss)r% O& A V%r"#!( '(!&% S)r*!#%

The following figure illustrates a hydrostatic pressure demonstration setup where the center of pressure of an immersed andpartial immersed vertical plane surface can be determined.

$"+)r% 2, Hydros!"# 'r%ss)r% D%-o&sr!"o&

urface@ idth of ?nd >urface# Total -epth of Auadrant& &entroid of ?nd >urface( &enter of (ressure of (lane >urface


7/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

3.2.1 '!r"!( I--%r+%d V%r"#!( '(!&% S)r*!#%

$"+)r% 3, '!r"!( I--%rs%d V%r"#!( '(!&% S)r*!#%


8/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

Theoretically, the center of pressure from the water surface, hB is expressed in ?"uation :)

−−=−=

Ah

IhY hh

cg

xx cp

θ sinD

*1+

The orientation of the surface from the hori!ontal ;6E gives 1 for sin5, then

Ah

Ihh xx +=D

*14+

%nd

12

3Bd I xx =

*'or a urface+ *17+

here, I xx is the moment of inertia of the submerged surface *please refer to %ppendix &+

The center of pressure bellow the fulcrum is finally determined by,

d Hhh −+= DC *1:+

Thus, substituting ?"uation 14 and 17 into ?"uation 1: will finally give,

3

d Hh −=C

*1;+


9/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

3.2.2 $)((y I--%r+%d V%r"#!( '(!&% S)r*!#%

$"+)r% , $)((y I--%rs%d V%r"#!( '(!&% S)r*!#%


10/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

Theoretically, the center of pressure from the water surface, hB is expressed in ?"uation :)

−−=−=

Ah

IhY hh

cg

xx cp

θ sinD

The orientation of the surface from the hori!ontal ;6E gives 1 for sin 5, then

Ah

Ihh xx +=D

−

××+

−=

2

11

122'

3

Dd

BD

BD Dd h

−

+

−

=

2

122

22

Dd

DDd

*22+

The center of pressure bellow the fulcrum is finally determined by,

d Hhh −+= DC

d HD

d

DDd

h −+

−

+

−

=

2

122

22

C

*2+


11/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

.0 EUI'MENTS MATERIALS

.1 D%s#r""o& !&d Ass%-(y

$"+)r% , Ass%-(y D"!+r!- o* Hydros!"# 'r%ss)r%

a+ Auadrant3aterial ) (F&Total -epth of Auadrant, # ) 266 mm#eight of 'ulcrum above Auadrant ) 166 mm#eight of ?nd >urface, - ) 166 mmidth, @ ) 7 mm=ength of @alance, = ) 66 mm

b+ uspended 3ass and 'ulcrum, =) 2;6 mm>et of eights) 6 gGeach

d+ Hverall -imension

=ength ) 6 mmidth ) 16 mm#eight ) 66 mm


12/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

.0 'ROCEDURE

1. (lace the #ydrostatic (ressure %pparatus on top of a hydraulic @ench.

2. 3ake sure that the apparatus is installed properly as in 'igure .

. =evel the apparatus using the adjustable feet facilitate by the spirit level attached.. %djust the counter$weight to level the balance arm to hori!ontal position.

. 3ake sure that the drain valve is closed and slowly add water into the tank until the surface just touches the "uadrant

base, thus establishing a datum level.

4.


13/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

$or-)(!

'!r"!( I--%rs%d $)((y I--%rs%d

2

2 Bd g F ρ =

−=2

Dd gBD F ρ

?xperimental)2

2"

Bd

mLh

ρ =

−

==

2

" D

d BD

mL

F

Lmg h

ρ

Theoretically) 3"

d H h −=

d H D

d

D Dd

h −+

−

+

−

=

2

22"

22

'ro%r"%s o* '(!&% S%#"o&s

G%o-%ry C%&ro"dMo-%& o* I&%r"!

I 9 9

'rod)# o* I&%r"! I 9 y

Ar%!


14/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

=.0 DATA ANALYSIS

>.0 DISCUSSIONS CONCLUSION

Prepared by / Disahkan oleh:

Signature/Tandatangan:

Name/Nama: DR. NOR FAIZAH BINTI RAZALI

DateTarikh :

Approved by / Disahkan oleh :

Signature / Tandatangan :

Name / Nama : PM. DR. ANGZZAS SARI

BINTI MOHD KASSIM


15/15


TECHNOLOGY

EDITION:

LABORATORY: FLUID



PRESSURE TEST


AMENDMENT

DATE:

exp 6 hydrostatic pressure

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