lab 3-FREE N FORCE VORTEX.doc

8/10/2019 lab 3-FREE N FORCE VORTEX.doc

1/18

ABSTRACT

This experiment was an experiment for investigate the vortices phenomenon. In these

experiment two observations was done. First observation was on the free vortices in this

experiment we recorded or sketch the profiles of vortices formed. The differences size of

orifice was used to control the outlet. Each of the orifice will result in differ vortex profiles.

Using a small orifice will formed small vortex. When large size of orifice used then large

vortex formed. For the forced vortex the time for revolution of impeller in the container

was recorded. Then the measured needle length hm also measured. Then calculation

was done to determine the height of hc.

INTRODUCTION

Vortex

In common usage b! vortex we usuall! mean a whirlpool or a circular cavit! formed b!

a li"uid in rotation. #ortex in fluid mechanics means a region of fluid bounded b! the so$

called vortex lines whose tangents at all points are parallel to the local directions of

vortices. The vortex lines which are the axes of rotation have to be either closed lines

or begin and end on the boundaries of the fluid or on the points in regions of infinite

vortices. % vortex induces an external fluid motion. % vortex is a form of kinetic energ!

the energ! of motion

The &hukovsk! theor! of conformal transformation shows that when a flow with

circulation around a circle 'vortex( is transformed into a flow past an airfoil the

circulation remains the same. % circle and a wing can replace the airfoil b! a circular

c!linder 'long vortex(. % bound vortex is imagined to be inside the wing and confined to

the wing. )ecause the aircraft wing can ever be infinitel! long the bound vortex too

must have an infinite length or span. &hukovsk! suggested that his bound vortex twists

at the tips of the wing and thus a horseshoe vortex s!stem is formed 'Tokat! *++,( from

reference [5].

1


2/18

Forces vortices

-ome of the important cases of forced vortexes are

The movement of the li"uids within the impeller of a centrifugal pump when there

is no flow as for example when the outlet valves are closed. The rotation of the li"uid within the confines of a stirrer in an agitated tank.

The rotation of li"uids in the basket of centrifuge

If li"uids contains in c!lindrical basket which is rotated about a vertical axis the surfaces

of constant pressure including the free surfaces are paraboloids of revolutions. In

generals the pressure at the walls was not constant but varies with height. /owever at

normal operating speeds the centrifugal forces will greatl! exceed the gravitational

forces and the inner surfaces of the li"uids will be approximatel! vertical and the wallpressure will be nearl! constant. %t high operating speed where the gravitational forces

and the inner surfaces of the li"uids will be approximatel! vertical and forces is relativel!

small the functioning of the centrifuge is independent of the orientation of the axis of

rotation. If mixtures of li"uids or suspensions are to be separated in a centrifuges it is

necessar! to calculate the pressure at the walls arising from the rotation of the basket

[1].

2


3/18

Application o vortex

In the engineering field there is a lot of vortex was appl! or used for particular purposes.

The example of vortex was appl! in engineering field is vortex water s!stem. % #ortex

Water -!stem means a worr!$free solution to refreshing well water stored water and

municipal water. % vortex s!stem custom$built for !our private well uses 0ature1s

process for restoring water. #ortex water is spun through a number of tubes to remove

iron and other minerals that results in rain$soft water that better tastes. It produces

health! water without polluting the environment as a salt t!pe conditioner does. This

s!stem was rediscovered after ,222 !ears from references [!]

-o this experiment was performed to determine the surface profiles of a forced vortex

and to investigate the ph!sical phenomena are visualized with the aid of d!e cr!stals

placed into the fluid.

3


4/18

T"#OR$

Theor! of force vortex

For a constant speed of rotation

rV = (1)

Where r 3 radius# 3 velocit! of flow at radius r

The speed of rotation can be obtained b! dividing the number of revolution obtained

from the experiment with the time taken for the revolution. Then the speed ' ( of

rotation can be obtained.

If the horizontal plane passing through the nadir 'lowest point( of vortex is taken asdatum theor! shows that

g

rhH

2

22

0

+= (2)

This is the e"uation of the parabola.

For this experiment 0h was assumed to be zero.

Theor! of free vortex

When water flows out of a vessel through a central hole in the base a free vortex is

formed. In a free c!lindrical vortex the velocit! varies inversel! to the distance from the

axis of the rotation.

r

kV = (3)

The e"uation governing the surface profiles is derived from )ernoulli4s Theorem

Czg

V=+

2

2

(4)

Thus

Czgr

k=+

22

2

(5)

4


5/18

Which is the e"uation to a h!perboliccurve which is as!mptotic to the axis of rotation

and to the horizontal through z 3 5

%ROC#DUR#S

6rocedure 7 e"uipment set 7 up

Force vortex

The apparatus was position in the working channel of the bench and the suppl! was

connected. The blanking plug was placed in into the central hole in the based of the

c!linder. The paddle was press on to the stud. % flexible hose was connected to the

outlet pipe and the outlet valve was closed.

Then the bench pump was switched on the bench control valve was opened and the

three wa! inlet valve too. -o that the water enters the c!linders from + mm tangential

inlet ports which was set at 82 degrees and leaves through the larger ports discharging

into the volumetric tank.

The outlets a pipe was raised and allows the water filled up and then lower it into the

volumetric tank. This induces a s!mphonic effect hence increasing the discharge rate.

Free vortex

The apparatus was positioned into the working channel of the bench and the suppl! was

connected. 9rifice was placed into the center hole in the based of the c!linder.

The bench pump was switched on the bench control valve was opened and also the

three wa! inlet valve. -o it allows the water enters the c!linder from the *: mm diameter

tangential inlets ports set at *;2 degrees and discharges through the orifice into the

volumetric tank.

6rocedures 7 Taking a set of results

5


6/18

Forced vortex

The bridge was placed with the measuring needles across the top of the c!linder. The

profiles of the surfaces were determined b! lowering the measuring needles until the!


7/18

Fi&'re () * height measuring device : radius measuring device > height sensor andpitot tube , transparent double$walled vortex tank ; interchangeable central drain 8drive motor for rotational movement ? controller housing

7


8/18

Fi&'re *) /!draulic bench for forces and free vortices

8


9/18

Fi&'re +)%n e"uipment for force and free vortices

9


10/18

T#C"NICA, DATA

6osition of needles for measuring profile of vortex 'from edge of tank(

Ta-le () Technical data

0eedle @adius 'm(

* 2.**

: 2.2+

> 2.2?

, 2.2;

; 2.2>

8 2.22

10


11/18

R#SU,TS

For forces vortices experiment

The result in table below was obtained b! performing an experiment for vortices. The

data obtained b! recorded the number of revolution time and measure of height fromdatum 'hm(. Then calculation was performed based on the result obtained to calculate

the height hc.

Ta-le *) Forces vortices experiment

No.N'-er orevol'tion/

N

Tie/ t0sec1

Revsper sec

rps/ 0

1

Ra2i's/r 01

3eas're2nee2le

len&t4/ 4n

01

"ei&4tro

2at'/

401

Calc'late24ei&4t/ 4c

01( *2 8.>: *.;A::?A 2.** 2.**; 2.**; 2.22*;,,

* :2 *>.*: *.;:,>+ 2.2+ 2.*>; 2.*>; 2.222+;+

+ >2 :*.?; *.>?+>* 2.2? 2.*,* 2.*,* 2.222,?;

,2 :+.>* *.>8,?:: 2.2; 2.*,+ 2.*,+ 2.222:>?

5 ;2 >8.2> *.>A??>: 2.2> 2.*;> 2.*;> A.A>E$2;

! 82 ,,.2, *.>8:>+A 2 2.*;? 2.*;? 2

For free vortices profiles experiment

This figure below was obtained b! an observation of profiles for each size of c!linder

controlling valve.

Vortex ore2Tan6

7ater

Fi&'re ) This figure was observed based on the profiles of free vortices b! using + mm

size of inlet port

11


12/18

Tan6 Vortex

7ater

Fi&'re 5) this sketch of free vortices profiles based on the observation made for *; mm

size of inlet port

Tan6 Vortex

7ater

Fi&'re !) This figure of free vortices profiles was sketch based on observation for :;

mm size of inlet port

12


13/18

DISCUSSIONS

Forced vortex

For the experiment of forced vortex some calculation has been done in order to

determine the value of hc. The value of hc is determined b! the e"uation 0*1. From theresult above when the revolution per second or the angular momentum decreased the

number or the value of the hc also decreased proportionall!.

Free vortex

For the experiment of free vortex an observation of vortex profiles was performed. In

this experiment three size of orifice was used. For the orifice size of + mm the vortex

form was in the smaller radius. For the second orifice which is *; mm in size the vortexformed was much larger than the orifice formed b! the + mm orifice. The used of orifice

in size of :; mm was the largest vortex formed. This phenomenon occurs because the

vortex formed is dependent on the size of the orifice used. From the experiment clearl!

when the size of orifice gets larger then the vortex formed will large too. This occurs

because when the orifice size gets larger the more water can flow out from the tank.

Then it not accumulated. When more water gets out the larger vortex formed. This

vortex was formed b! the force of water flow in the tank. The flow pattern formed is in

circumferential.

For the observation of destruction of the vortex a core ob


14/18

of the diameter will result in decreased pattern if the measurement was taken

proportionall! to the depth of the vortex formed.

CONC,USIONS

From the result obtained from the experiment we can conclude that the formed of the

vortex is dependent on the size of the orifice used. The larger the orifice used the larger

vortex will be formed. The disturbance that can destro! the orifice is when some core

ob


15/18

R#FR#NC#S

[(]D 5oulson B DF @ichardson 5hemical Engineering volume * 8 thedition page ;>

[*]httpwww.gunt.dedaten2?2*;2*,datenblatt2?2*;2*,G:2:.pdfHsearch31free

G:2andG:2forcedG:2vortices1

[+] , httpwww.armfield.co.ukfluid.html

[]httpwww.gunt.dedaten2?2*;2>*datenblatt2?2*;2>*G:2:.pdfHsearch31vortices

G:2inG:2waterG:2inG:2theG:2tank1

[5]httpwww.coachesinfo.comarticle*8;Hvortex

[!]httpwww.environmentsensitive.comvortex.html

15
http://www.armfield.co.uk/fluid.htmlhttp://www.coachesinfo.com/article/165#vortexhttp://www.coachesinfo.com/article/165#vortexhttp://www.armfield.co.uk/fluid.htmlhttp://www.coachesinfo.com/article/165#vortex


16/18

A%%#NDIC#S

Full calculation

5alculation for

0o. of revolution of *2

Time for the revolution 8.>: s

@adius r 3 2.**2 m

easured needle length hn3 2.**; m

@evolution per second revs 332.6

10

3 *.;A:> revs

hc3g

r

2

22

381.9*2

)110.0)(5823.1( 22

3 *.;,,* x *2$>m

5alculation for

0o. of revolution of :2

Time for the revolution *>.*: s

@adius r 3 2.2+2 m

easured needle length hn3 2.*>; m


20

3 *.;:,, revs

hc3g

r

2

22

381.9*2

)135.0)(5244.1( 22

3 :.*;A8 x *2$>m

5alculation for

16


17/18

0o. of revolution of >2

Time for the revolution :*.?; s

@adius r 3 2.2? m

easured needle length hn3 2.*,* m


30

3 *.>?+> revs

hc3g

r

2

22

381.9*2

)141.0)(3793.1( 22

3 *.+> x *2$>m

5alculation for

0o. of revolution of ,2

Time for the revolution :+.>* s

@adius r 3 2.2;2 m

easured needle length hn3 2.*,+ m


40

3 *.>8,? revs

hc3g

r

2

22

381.9*2

)05.0)(3647.1( 22

3 :.>?> x *2$,m

5alculation for

17


18/18

0o. of revolution of ;2

Time for the revolution >8.2> s

@adius r 3 2.2>2 m

easured needle length hn3 2.*;> m


50

3 *.>A?? revs

hc3g

r

2

22

381.9*2

)030.0)(3877.1( 22

3 A.A>, x *2$>m

5alculation for

0o. of revolution of 82

Time for the revolution ,,.2, s

@adius r 3 2 m

easured needle length hn3 2.*;? m


60

3 *.>8:, revs

hc3g

r

2

22

3

81.9*2

)0)(3624.1( 22

3 2 m

18

Date post:	02-Jun-2018
Category:	Documents
Upload:	fahmirased
View:	214 times
Download:	0 times

lab 3-FREE N FORCE VORTEX.doc

Documents