CHEMICAL ENGINEERING ENGINEERIN G LABORAT LABORATORY ORY 1 CHE150-1L/B41
Experiment 1: Fluid Flow Reime! "Re#nold! Num$er Nu m$er App%r%tu!& App%r%tu!& Mendo'%( T)ere!% C 1 1
Student, School of Chemical Engineering En gineering and Chemistry, a!"a #nstitute of $e $echnology, chnology, anila, %hili!!ines AB*TRACT
$his e&!eriment studies fluid flo' regimes (y analy)ing the flo' !attern of the dye in 'ater* $he fluid flo' regimes are laminar, transition, transition, and tur(ulent flo'* +eynolds um(er !!aratus !!aratus is used for this analysis through o(ser.ing the dye 'ith 'ater that flo's out of the discharged .al.e* Before doing so, the dye in the smaller internal !i!e must (e distinct, straight, and smooth* $he o(ser.ed flo' !attern of the dye in 'ater can (e !ro.en right (y means of +eynolds um(er* $his +eynolds um(er 'as a(le to get (y the !arameters 'hich are the inside diameter of the !i!e and .elocity, density, .iscosity of 'ater* $he inside diameter of the !i!e is constant 0*0 m 'hile the density and .iscosity is de!endent on tem!erature of 'ater* 2olu 2olume me of the 'ater !er ten seconds and the cross sectional area of the !i!e 'hich is 0*000441 m3 are needed to com!ute for the .elocity* .elocity* $he .alues of +eynolds num(er corres!onded to the ty!e of flo' o(ser.ed* Keywords: Keyword s: Flow Pattern, Pattern, Reynolds number number,, Fluid Flow Regimes
1.
Introd Int roduct uction ion
$'o ty!es of flo' regimes 'ere first suggested (y end endel elee ee.., a +uss +ussia iann scie scient ntis ist*t* $hro $hroug ughh se.e se.era rall e&!eriments, s(orne +eynolds gi.es scientific and !recise 'ay in differentiating the t'o flo's from each other* He found out in his study that the .alue of a dimensionless !arameter 'ith iameter/Length, iameter/Length, .elocity, .elocity, density, density, and .isc .iscos ositityy gi.e gi.ess (asi (asiss in dist distin ingu guis ishi hing ng lami lamina narr and and tur(ulent tur(ulent flo'* +eynolds num(er num(er is that dimension dimensionless less !arameter* !arameter* 6Balachandran, 0117 0117 ρVd μ
ℜ=
(1)
$he +eynolds E&!eriment identifies the critical +eynolds um(er 'hich indicates 'hen the flo' (ecomes laminar, transitional, and tur(ulent* #t has (een found that the lo'er critical +eynolds um(er for ordinary !i!es is 100 'hile the higher is 4000* $he +eynolds um(er less than 100 is said to (e laminar, greater than 4000 is tur(ulent and in (et'een these t'o .alues is transition* 68ang, n*d7
#n this e&!eriment, the (eha.ior of the dye in 'ater has (een o(ser.ed and its relation to +eynolds num(er has (een inter!reted* 2.
Method Met hodolo ology gy
Materials and Equipment
$he !rimary e9ui!ment used to meet the o(:ecti.es in this e&!eriment is the +eynolds um(er !!aratus 6see ;igure *17* $his a!!aratus consists of a dye .essel, head tan<, inside !i!e, gate .al.e, 'ater inlet, and t'o outlets* side from +eynolds um(er a!!aratus, dye, thermometer, sto!'atch and (ea
Experimentation Experimentation Figure 2.1 Reynolds Number Apparatus
Beginning 'ith the e&!eriment, the a!!aratus 'as checean
1 &10-5 0*051 3 4*5&10-5 0*10 ?*5&10-5 0*1 1&10-4 0*0? 4 5 ?*5&10-5 0*11? Table 3.1 Volumetric Flow Rate and Velocity obtained from the eperiment
$a(le * sho's the calculated +eynolds num(er, the o(ser.ed flo' !attern, and the ty!e of flo'* ;or trial 1, the o(ser.ed (eha.ior or flo' !attern of the dye is smooth and does not mi& 'ith 'ater* $he o(ser.ation is merely right for the calculated +eynolds um(er is 1?4*15 'hich is less than 100 corres!onding to laminar flo'* $he o(ser.ation for the second trial is unsta(le (eha.ior of the dye* $he ty!e of flo' in this trial is transition since ?*4, calculated +eynolds num(er, is (et'een 100 and 4000* ;or the last three trials, the flo' is tur(ulent since the .alue of +eynolds num(er are all greater than 4000* $he flo' !atterns of the three are also the same 'here no dye color can (e seen in the 'ater collected*
Results and Discussion
%ro!erties of 'ater and characteristics of the !i!e is im!ortant for most com!utations needed in this e&!eriment* $he data (elo' sho's the tem!erature of 'ater o(tained and its corres!onding density and .iscosity found in >ean
Tri%l
Nre
Flow +%ttern
T#pe o, ,low
1 3 4 5
1?4*15 ?*4 51*0 1*54 510*?
Smooth Dnsta(le Dnsta(le Dnsta(le Dnsta(le
Laminar $ransition $ur(ulent $ur(ulent $ur(ulent
Table 3.2 Reynolds Number calculated! "bser#ed
$rials 1-4 Flow $attern and their corresponding type of %ow ha.e an increasing .elocity calculated using the formula
$em!erature @ 4 AC ensity @
993.402
V =
kg m
´ V
A
(2)
3
8here
2iscosity @ 0* c%
V ´
is the .olumetric flo' rate of 'ater and is
the area of the !i!e* Values were obtained from Transport Proesses and !eparation Proesses by "ean#oplis C)%r%.teri!ti.! o, t)e pipe
#nside iameter @ 0*00 m Cross-Sectional rea @ Tri%l
/( m02!
−4
3.441 x 10
m
2
u( m2!
#t has (een o(ser.ed that as the .olumetric flo' rate or .elocity increases the +eynolds num(er increases* +eynolds num(er 'as calculated using e9uation 617 nother definition of +eynolds um(er is it is the ratio of inertia force o.er .iscous force 67* $hen, if the +eynolds num(er is large inertia force !redominates* Ho'e.er, if the +eynolds um(er is small, .iscous force !redominates* ;lo' 'ith lo' .elocities, the flo' is !redominately .iscous
'hich is termed to (e laminar* ;lo' 'ith high .elocities, inertia force is high com!ared to .iscous is tur(ulent* 68ang, n*d7 N ℜ=
inertia forces viscous forces
67
;igure *1 sho's the flo' !attern of the dye in 'ater for e.ery ty!e of flo'* $he results in $a(le are some'hat acce!ta(le* #n the first trial 'here the .elocity is lo', the fluid !articles mo.e in layers* $he .elocity is slightly increased in the second trial causing 'a.iness to de.elo!* $he !attern is unsta(le 'hich is !ro.ed (y the .alue of +eynolds num(er 'hich is close to tur(ulence* ;urther increase in .elocity is a!!lied in the last three trials, therefore, the stream fluctuates* $his leads to (rea
4* Conclusion ;or the four trials of this e&!eriment, the +eynolds um(er increases as the .olumetric flo' rate increases* So, they are directly !ro!ortional to each other* $hese flo' rates or sim!ly the .elocities of the fluid indicate 'hat force !redominates and the ty!e of flo'* $he flo' is laminar for lo' .elocities 'hile it is tur(ulent for high* $he flo' !atterns o(ser.ed in the e&!eriment is also one 'ay to identify the ty!e of flo'* Smooth flo' of the dye means that the flo' is laminar 'hile unsta(le flo' is for the tur(ulent flo'* $he !attern of the transitional flo' de!ends on the .alue of +eynolds num(er* #n this e&!eriment, the calculated .alue for transition flo' is close to 4000 'hich e&!lains the insta(ility of the flo'* $he !ossi(le sources of error, if e.er there is, might (e the amount of dye filled in the dye .essel for as the .elocity increases, the amount of dye must also increase* $his is in order to clearly see the !attern made (y the dye in the e&!eriment* References
Balachandran, %* 60117* Engineering ;luid echanics* e' elhi %H# Learning %ri.ate Limited* 8ang, * L* 6n*d*7* EE>1 #ncom!ressi(le ;luids La(oratory * +etrie.ed !ril , 01?, from Dni.ersity of ela'are College of Engineering htt!//research*me*udel*edu/Gly'ang/meeg1/la(s/reynold s*!df .
Figure 3.1 Flow of &ye in di'erent types of %ow
