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UNIVERSITI TEKNOLOGI MARA FAKULTI KEJURUTERAAN KIMIA THERMOFLUIDS LABORATORY (CGE 536)
E?PERIMENT DATE PERFORMED SEMESTER PROG PROGRA RAMM MME ECO CODE DE GROUP
> FREE AND FORCED VORTE? > 00206 >3 > TH THER ERMO MOFL FLUI UIDS DS LABO LABORA RAT TORY ORY CGE5 CGE536 36 > EH2#33A
NAMA ADIL RAHMAN BIN NOR AZMI NABILA BINTI ALI MOHAMAD FAIZ BIN MOHAMAD AMIN JAC$UINN ALIZCIA AK JAMES KETEK
%&' 2 3 # 5 6 < " ! 0 2 3
T*+ ,4,-//,7 I%&.-&% ,/&48+-9+ T:+&7 A;;,, ;&-+.+ R+* -,*-*,&% D-&% -&%-*&% +-&//+%.,&% R+=++%-+ ,;;+%.-+ T&,* R+/,1 > C:+-1+. 47>
NO PELAJAR 20522!"2" 205#302# 20520#!0" 2052"0#
,**&-,+. /,1 5 5 5 5 5 0 0 0 20 0 5 5 5 00
M,1
T,4*+ &=
Content
TABLE
C&%+%> OF
Summary Introduction Objectives Theory Apparatus/ Materials Procedure Result iscussions Conclusions Re!erence Appendices
CONTENT
Pages
ABSTRACT
This experiment was carried out to study the free and force vortex. The objectives for the free vortex experiment are to study the relationship between the surface profile and speed. Meanwhile, for the force vortex experiment, are to find the relationship between the surface profile and total head. Vortex is the rotation of fluid elements around a common centre. The concept of this experiment was being used in various types of industry such as turbine design and in creating standard safety against natural disaster. The angular velocity of the fluid was manipulated by adjusting the control valve to provide different flow rate of fluid flow. The height of the vortex profile was measured when it maintained constantly at its maximum height. Furthermore, when the angular velocity of the fluid in the cylinder increases, the depth of each pointer at the different vortex radius will also increases due to formation of semiparabolic shape. Thus, it was concluded that the height of water surface level relative to the lowest point of the surface of a forced vortex flow was directly proportional to the angular velocity of a rotating liuid in a cylindrical tan!.
INTRODUCTION
"nalysis of fluid flow is often accomplished by simplifying assumptions with respect to the !inematics of the flow, by assuming simplified patterns of fluid motion as represented by streamlines. Vortex motion is a basic flow pattern, it is defined as motion in circular paths. There are two types of vortices distinguished in the dynamics of the motion and the resulting velocity distributions. These are forced and free vortices. The forced vortex is caused by external forces on the fluid such as the impeller of a pump. #n a forced vortex motion, the fluid mass is made to rotate by means of some external source of power, which exerts a constant torue on the fluid mass and, therefore, the fluid mass rotates with a constant angular velocity. For example, a vertical cylinder containing liuid and rotating around its central axis with a constant angular velocity flow through the impeller of a centrifugal pump. #n the free vortex motion, the fluid mass rotates without any external force. #t rotates either by internal action or due to some rotation previously imported to it. For example, flow through an opening at the bottom of a shallow vessel such as washbasin or a bathtub, flow around a bend, whirlpools, or tornadoes. #n this experiment, a forced vortex is created by a rotating plate filled with blades while free vortex is created by only a rotating plate.
OBJECTIVES
$xperiment % & Free Vortex T' (T)*+ T$ ()F"$ /'F#0$ "1* (/$$*. T' F#1* " $0"T#'1(#/ 2$T3$$1 ()F"$ /'F#0$ "1* (/$$*.
$xperiment 4 & Forced vortex • •
T' (T)*+ T$ ()F"$ /'F#0$ "1* "15)0" V$0'#T+. T' F#1* " $0"T#'1 2$T3$$1 T$ ()F"$ /'F#0$ "1* T'T"0 $"*.
THEORY
A vorte" is the rotation o! !luid elements o! !luid elements around a common center# According to Rajput $%&'&() the vorte" motion is de!ined as a motion in *hich the *hole !luid mass rotates about an a"is and the mass o! !luid in rotation about a !i"ed a"is is called vorte"# The e"amples o! a vorte" are the atmospheric phenomenon o! a *hirl*ind) a tornado or dust devil and also a vorte" !ormed *hen *ater goes do*n a drain such as in a sin+#There are t*o types o! vorte" !lo* *hich are !orced vorte" !lo* and !ree vorte" !lo*# According to ,ebber $'-.'() the !ree vorte" essential characteristic in ideal !luid that it does not reuire the application o! e"ternal energy !or continuance and !orced vorte" is produced and maintained by application o! e"ternal !orces# This e"periment is only !ocusing on !orced vorte" !lo*# In a !orced vorte") !luid circles around a centre) *hile in a !ree vorte" the medium spirals to*ard the centre# The speed and rate o! rotation o! rotation o! the !luid are greatest at the centre) and decrease progressively *ith distance !rom the centre#
The e"ample o! !orced vorte" motion are that o! a vertical cylinder containing liuid rotated about its central a"is *ith constant angular velocity) the !lo* o! liuid inside the impeller o! a centri!ugal pump and !lo* o! *ater through the runner o! a turbine# This e"periment is a theory about the !orced vorte") !lo* sur!ace shape o! !orced vorte" and the angular velocity o! a rotating liuid in a cylindrical tan+#
APPARATUS '# SO0T12 3 4ree and 4orced 5orte" %#epth gauge 6# Ruler
7# Stop*atch
PROCEDURE
Experiment 1: Free Vortex Procedures:
1. Performed the general start-up procedures. 2. An orifice with diameter 24mm is selected and placed on the base of cylinder tank. 3. The output valve is closed and the inlet 3-way valve is adusted to let the water flows into the tank from two pipes with !2." mm diameter. The water flow out through the orifice. 4. The pump is switched on and the control valve is open on the hydraulic bench slowly until the tank limit. #aintain the water level by adusting the control valve. 5.As the water level is stable$ the vorte% profile is collected by measuring the vorte% diameter for several planes using the profile measuring gauge. 6. The profile measuring gauge is pushed down until the both of sharp point touch the water surface. 7. The measured height$ h &from the top of the profile measuring gauge to the bridge' is recorded. The value of a &distance from the bridge to the surface of the water level &bottom level of the cutout'' is obtained. 8. The pitot tube is used to measure the velocity by sinking it into the water at the depth of "mm from the water surface. #easure the depth of the pitot tube in the water$ (. ). *epeat step 3 - + for another three orifice with diameter !2mm$ !,mm and +mm respectively. !. Plot the coordinates of vorte% profile for all diameter of orifice in graph and calculate the gradient of graph as shown below
/0 1here / is the pressure head depth of the pitot tube. !!. Plot graph of velocity which is calculated from the pitot tube reading versus the radius of the profile. 0 &2g(' ."
Experiment 2: Forced Vortex Procedures:
1. Perform the general start-up procedures. 2. A closed pump is placed with two pedals on the base of the cylinder tank. 3. The output valve is closed and adusted the inlet 3-way valve to let the water flows into the tank from two pipes with ). mm diameter. The water can flow out through another two pipes with !2."mm diameter. 4. #ake sure that the water flow out from the tank with the siphon effect by raising the hose to above the water level in the tank. 5. #ake sure the outlet hose is fill with water before letting the water to flow into the
sump tank in the hydraulic bench 6. The angular speed of the pedals is measured by counting the number of circles in a certain time. 7. The surface probe is pushed down until the sharp point touch the water surface. 8. *ecord the measured height$ h &from top of the measuring gauge to bridge'. 9. *epeat step 4 - + with different volumetric flow rate. 10. Plot the coordinates of vorte% profile for different angular velocity. 11. Plot the calculated vorte% profile in the same graph as they relate as
h 0 h r 2
RESULTS E@;+/+% > F++ V&+@
D,/++ , C+%+ D (//)
M+,+ . H+: : (//)
P& T4+ H+,. D==++% -+ H
P++ H+,. D+;: &= :+ P& T4+ ?
(//)
(//)
(//)
(//)
(//)
%7
86
&#-
%9%
'%
'77
&#&&8-
'8
97
'#%
%7.
:
87
&#&'98
'%
8-
&#:
%7:
8
68
&#&%.:
:
.6
&#-
%78
7
'8
&#&8%9
E@;+/+% 2> F&-+. V&+@
D,%-+ =&/ C+%+(//)
:& (-/)
2%.
3.
0
6
79
.9
30
6
97
.8
<0
7#'
98
.-
00
7-
9:
:'
N& &= +9&*&% % 60
67
69
6.
A%*, V+*&-7(,.)
7#&:
6#8.
6#69
X-Y Equilibrium 0.07 0.06 0.05 0.04
P++ H+,. ? (//)
0.03 0.02 0.01 0 245
246
247
248
249
R (//)
;radient o! the graph < 7%9& mm 6
<7%9& There!ore) = < %:- mm %/s V =
K r %:'%
< < %7#&:6 mm/s
As a result) (//)
'%
C,*-*,+. V+*&-7 (//) %7#&:6
:
68#'%9
8
7:#'8.
250
251
252
253
7
.%#%9&
80 70 60 50
V+*&-7 (//)
40 30 20 10 0 3
4
5
6
7
8
9
10
R,. (//)
F+ V+*&-7 ,,% R,.
11
12
13
E@;+/+% 2> F&-+. V&+@
D,%-+ =&/ C+%+(//)
:& (-/)
2%.
3.
0
6
79
.9
30
6
97
.8
<0
7#'
98
.-
00
7-
9:
:'
N& &= +9&*&% % 60
67
69
6.
A%*, V+*&-7(,.)
6#98
6#8.
6#::
Calculation 4or the 'rd volumetric !lo* rate> ?umber o! revolutions in 8& seconds> 67
%$6#'7%( × 67 8& <
< 6#98 rad / s h&
h<
+
w% % g
r %
+ <
6
6#98 % %$-#:'($'&&&(
×
6& %
< 77#.8mm $calculated( C,*-*,+. 9,*+ >
D,%-+ =&/ C+%+(//)
: (//)
2%.
3.
0
6
79
.9
30
6#9:'
97#8'8
.8#8:-
<0
.#%8.
9-#698
:%#.9&
0
98#:%&
88#%:.
-&#%8'
N& &= +9&*&% % 60
67
69
6.
A%*, V+*&-7(,.)
6#98
6#8.
6#::
F&-+ V&+@ 60 50 40
(i$t%nce #rom centre &mm'
Exp1
30
Exponential (Exp1) Exponential (Exp1)
20
Calc1 Exponential (Calc1)
10 0 0
30
70
110
ei!"t #rom top o# t"e $ur#%ce probe to t"e brid!e &mm'
F++ V&+@ 2%.
70 60 50 40 (i$t%nce #rom centre &mm'
Exp2 Exponential (Exp2)
30
Exponential (Exp2)
20
Calc2 Exponential (Calc2)
10 0 0
30
70
110
ei!"t #rom top o# t"e $ur#%ce probe to t"e brid!e &mm'
F++ V&+@ 3 . 100 90 80 70 60 (i$t%nce #rom centre &mm'
Exp3
50
Exponential (Exp3)
40
Exponential (Exp3)
30
Calc3
20
Exponential (Calc3)
10 0 0
30
70
110
ei!"t #rom top o# t"e $ur#%ce probe to t"e brid!e &mm'
DISCUSSION
4or e"periment ' *hich is !ree vorte") it is needed to calculate the velocity o! *ater using di!!erent ori!ice *hich is %7mm) '8mm) '%mm) and :mm that is in!luenced by the radius o! the *ater pro!ile# 4or e"periment ' it can conclude that the velocity o! the *ater increased as the radius o! *ater pro!ile decreased# The gradient calculated *as 7%9&mm 6 and the value o! = *as %:- mm %/s# 4or *ater pro!ile *ith radius o! '% mm the calculated velocity value is %7#&:6mm/s# 4or :mm the calculated velocity value is 68#'%9 mm/s# 4or *ater pro!ile *ith radius 8mm the calculated velocity value is 7:#'.mm/s and the lo*est *ater pro!ile *ith radius o! 7mm the calculated velocity is .%#%9mm/s# The calculation is based on the graph plotted using the euation 5<=/r 4or e"periment % *hich is !orce vorte") it is needed to obtain the sur!ace pro!ile and the total head distribution in a !orced vorte" !lo* and compare *ith theoretical values# @ o *as recorded and measured by ta+ing & mm) 6& mm) .& mm and ''& mm diameter at the centre# 4or !irst trial) @o *as 6 mm distance ta+en !rom centre & mm) 6 mm distance ta+en !rom centre 6& mm) 7#' mm distance ta+en !rom centre .& mm) and 7- mm distance ta+en !rom centre ''&mm# The number o! revolution counted !or 8& seconds is 67 times) *hile the angular velocity is 6#98 rad/s# The h calculated !or the !irst trial are 6 mm) .#%8. mm) 7-#'9 and 98#:%& mm !or & mm) 6& mm) .& mm and ''& mm respectively# 4or second trial) @ o *as 79mm distance ta+en !rom centre & mm) 97 mm distance ta+en !rom centre 6& mm) 98 mm distance ta+en !rom centre .& mm and 9: mm distance ta+en !rom centre ''& mm# The number o! revolution is counted 69 times in 8& seconds *hile
the angular velocity is 6#8. rad/s# The h calculated value *as 79 mm) 97#8'8 mm) 9-#698 mm and 88#%:. mm !or & mm 6& mm) .& mm and ''& mm distance !rom centre respectively# 4or third trial) @ o *as .9 mm distance ta+en !rom centre & mm) .8 mm distance ta+en !rom centre 6& mm) .- mm distance ta+en !rom centre .& mm and :' mm distance ta+en !rom centre ''& mm# The number o! revolution is counted 6: times in 8& seconds *hile the angular velocity is 6#:: rad/s# The h calculated value *as .9 mm) .8#8:- mm) :%#.9& mm and -&#%8 mm !or & mm 6& mm) .& mm and '&& mm distance !rom centre respectively#
CONCLUSIONS
4rom e"periment ') based on the result recorded) it can conclude that the velocity o! the *ater increased as the radius o! *ater pro!ile decreased# It can be proved by *ater pro!ile *ith radius '%mm the calculated velocity value is %7#&:6 mm/s# 4or lo*est *ater pro!ile the calculated velocity value is .%#%9 mm/s# The theory *as proved# This theory is also valid !or other ori!ice diameter# 4or e"periment %) this e"periments needs to obtain the sur!ace pro!ile and the total head distribution in a !orced vorte" !lo* and compare *ith theoretical value# It can be conclude that the height o! vorte" pro!ile increased as the diameter !rom centre increased# ?e"t) according to the theory) the value o! angular velocity should constant !or every tr ial but *e get increased value o! angular velocity# This may due to maintain the *ater level that !lo* into the container *hich *e must +eep it constant to avoid increased and decreased o! impeller rotation per 8& seconds#
RECOMMENDATIONS
'# %# 6# 7# 9#
The Apparatus that *e use must be !ree !rom any dust Clean *ater should be used Oiling and greasing o! the parts should be done at regular intervals Ta+e readings i! the *ater is already in steady state The eyes must be parallel *ith the rulers reading scale in order to avoid paralla" error *hile ta+ing the height) h# 8# ,ater valve must be controlled in order to obtain a stable *ater level as *ater level decreases over time i! the valve stayed at the same opening .# Ma+e sure the e"periment conducted in three di!!erent *ater levels# :# Set a mar+ be!ore recording on ho* many lap does the paddle can ma+e in a minute so that the reading is accurate as a complete lap can be detected *hen the paddle *ith the *hite mar+ passes through a !i"ed point#
REFERENCES
'# 4luid Mechanics laboratory ) $%&'7( http>//***#uet#edu#p+/!aculties/!acultiesin!o/chemical/0abs/4luidMechanics#pd! %#
,i+ipedia) $%&'7() 5orte") http>//en#*i+ipedia#org/*i+i/5orte"
6# Pattison) M#B# $no date() 5ortices http>//***#thermopedia#com/content/'%7:/tid<'&7Dsn<''97# Theory o! a 5orte" E 1"plore *ith 4ouFan#$n#d#(# Retrieved April 9) %&'9) !rom http>//!ouFan#*eebly#com/theoryEo!EaEvorte"#html
APPENDICES
The apparatus SO0T12 3 4ree and 4orced 5orte" $Model> 4M7%( used in this e"periment
Measuring the vorte" diameter !or several planes using the pro!ile
