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-- l- -
TEC0ICAL MOR NO. 13
A
LIQIUD AD GAS DISTRIBUTZC 13
TD-PASE
3E G AWALOGE
BY
Graham 3.
Pter Griffithi
For the Office of Naval Research
Contract No. N5 orL-07894
YOUR - 1848(39)
DSR aOnoT o. 7.7673
December 1, 1958
DIVISIK OF IDUcSTRIALCP
'a
Masachusetts Institute of Technology
Ceabr.dge, Massachusetts
- Research Assistant, Departent of Rechanical Engineering
assachusetts Institute of Technology, Cambridge,
Oassachusette
Assistant Professor of Mechanical E!gineering, Massachusetts
Institute of Tehnology, Cambridge, Massaehusetts
ZAMU-2m
- I-
M..
1- 2
3
/-12
13-17
1-23
24-28
29
30
31
32
33-34
35
Abstract
Nomenclature
Introduction
Description of the Analogy
Description of Apparatus
Description of Experiments Using the Straight Mni'
Deacription of RxpmIeumts with the Scoop
Photographs of Flow Patterns
ppendix A
Appendix B
Appendix C
Appendix D
Description of Illustrations
Acknwledgemnts and References
Figures 1 - 97
ABSTRACT
This report contains a description of the design and operation
of an experimental appats for the analysis of two-phase flows similar
to thom occuwring in boiler tubes at low pressures.
Velocity and denuity
profiles of air-water mixtures are determined across a passage in which
boiling Ocditiosis are simulated by puping air through porous walls into
a water strea.
Photographs of the flow patterns are also presented as a
qualitative check on the quantitative data.
The results obtained are:
1)
Vslocity and concentration profiles of the two phases for
various values of the flow rates of each.
2)
A classification of the flow into several patterns or regimes
with quantitative data describing each regims.
The data is suitable for use In acapering the physical phenen
with
athematical models and for developing a more accurate theoretical
treatment of the flow of boiling fluids in heated channels.
D
channel width
f(x) = Ji)
flow fraction intercepted by knife at Wx
100
G(Z)
h
P
p
AP
q/A
rate of flow at 3xv
enthalpy
knife position, micrometer reading, thousandtbs of an inach
Pressur
pressure drop
heat fluz
Q
dryness
total flar, c.f.n.
T
specific Volume
V
V
I
x
valuma
total mass flow
water concentration
distance from channel wall
a
L
I
air
lef'-hand sids
right-head side
total channel
water
value 6f properties at x
Sstem
T
W
x
INTROMCTIO
The study of two-phase flow with boiling is of particular
interest to heat transfer engineers in many fields.
Nuclear reactors
and rocket motors are obvious examples.
A number of theories, correlations and theoretical analyses
are avalable in the literature on the various aspects of two-phase
flows with heat addition.
All of them suffer from the same disadvantage,
a lack of experimental information concerning the pbysical processes
occurring.
It is all very well to postulate a flow pattern;
quite
another thing to show that it actually corresponds to realit.
The
objective at these eperiments was to observe the flow patterns and
liquid and gas distributions in a chanel in which heat addition was
simlated.
This information will be of assistance in framing analytical
models which are appropriate for pressure drop, liquid distribution and
burnout calculations.
In this report we describe a method for masuring the distribution of concentrations and velocities of the two phases across a simple
charnel.
Boiling is simulated by pumping air through the porous bronse
walls of the chnnel.
eadt.
The flow is analysed over a crosa.-section at the
Flash photographs are also made of the flow itself to check results
and to show the patterns present along the length of the streas.
Every eperiment performed is described.
Because these methods
have not been used before, to the author's knowledge, it was considered
worthwhile to give all details of the development of techniques and the
various problems emncotered and to try to show the capabilities and
limitations of this kind of apparatus.
.
2 -
The apparatus and experiments are reviewed criticaily throughout
the report.
Certain definite conclusions are drawn about the nature of
two-phase flow patterns and the velocity and density distributions In the
passage.
Parallels are drawn between the flow of air-vater mixtures with
air addition through porous walls and the corresponding problem of the
flow of boiling fluids in heated pipes such as boiler tubes, reactar
coolant chamnels, etc.
Suggestions are made as to further similar experiments which couid
be performed.
lopes are entertained that an analysis of two-phase flows on these
lines will lead to a fuller understanding of the phenoma
and the eventual
development of an effective mathematical theory to predict pressure drops,
burnout points, heat transfer coefficients, and other importsat engineering
data.
DESCRITION OF TE ANA~GY
The basic feature of the flow of a boiling fluid in a heated
tube is the continuous creation of the vapor phase at the walls.
The
phase may be created in the form of bubbles, small or large compared
with the channel dim
aiOns, or conceivably in the form of a sheet or
fila of vapor.
It has been observed that several possible flow regimes exist
for two-phase boiling airtures, BbbLy", 'ananlar 5 , 8slug', 'dropwise',
and combinations of these, are weil know adjectives used to describe
patterns and there is no need to dwell on the subject.
We shall proceed
with the description of the analogy.
The vapor which is created on the walls of a boiler tube is
represented in thi. analogy by air. To obtain conditions of surfaae
nucleation similar to those prevailing under boiling conditions, a uperfine grade bronse filter material is used through which the air is pumped
into the water streame.
Each pore becomes a bubble nucleation point and
under normal oonditions the bubbles will grov at these points and be swept
aWay into the main stream.
It is claimed that a distinct parallel exists
between the flow regions observed under these conditions and those prevailing In a boiler tube of similar geomtry.
Further, it has been suggested that the barmnut heat flux is
determined entirely by lydrodynamic considerations.
In this case it sem
reasonable to expect that the analogy will throw light on this phana
as Vell.
-Ow
-
DSIPI
OF APPARBTUS
(Figs. 1-8)
Bimulated Uilinpr Test Sectia
The test section is modelled after one previousy built by
Marlon D. R~ller and operated by R di Wensa (refol) in the Heat
fransfer Laboratory at the Masacasette Institute of TeOlo1g.
The idea Is to simalate the generation of bubbles at a boiling surfa"e
by p=ping air tbrough a porous bronse filter material into a stream of
Water.
Numerous geomstries are, of oose, possible.
In this apparatos
we have chosen one of the simplest, a rectangular passage.
Two Walls of
the passage are the 'boiling' surfaces consisting of 3/2-inch wide bronse
hese are claMped 3/4-inch apart between two sheets of plexiglas
strips.
The
transpsrest plastic so that the flow may be viewed and photographed.
whol. assenbly is show in Tig. 5.
behind the bronse.
ear air lines feed the pleom chaibes
Two others feed a siing chamber before inlet to the
passage so that any desired inlet quality may be obtained.
Each air line
has its ow needle valve.
Water enters by the central tube at the top and flows via the
mixing chamber to the simulated boiling section.
The frame is out from 3/2 brass to which the bronse strips are
soldered.
shown.
The pleaiglas sides are clasped firmly by the bolts and mate
The cross-pieces are stainless steel spring strips which are needed
to ensure that the plexiglas, which is slightly flexible, grips the bronse
firmly.
Gaskete between the plexiglas, bronse and brass are of cork out
from a single sheet.
This material was fond to provide the best solution
after experiments with various kinds of rubber
rnd
water lines are firmly brased in the brass frame.
fabric gaskets.
Air and
M 5 -
The whole assembty is glued to the plexiglas base plate which is
designed to Alide an the top surface of the air-water separating
chambers described later.
Fow Samplin
Telean
We desire to mamre the air aod water veoeaity distribution
aeross the outlet from this passage.
A kind of saqling devise or
pitot tbe is of geestmble vale in a flow ocasisting of bubbles ad
drops, sine mnty and surface t
amnes.
I be of nYva
ia
effects are of pr-
suoh a devicem ould have to be about the sine
of the ohomel itself. Since we shld lik, a rsoin
the of an 4ic,
-ta i Import.
s
to a few thand.-
sch an arrangmnt is obvioasly ile0ctiea.
!he solutimo
to this problem is to out the eait flov Into tm parts
by passing it overa sharp straight knife-edge
uater flows n each side of the blade.
barrier to the fli..
nd to aaur the air A
The edge represents a negligible
To obtain mass flow distributons all that is
necessary is to differantiate the readings as the knife is nwed across the
*mi.a1
2he differvatiating process is a source of inaocuray but this
ma be ofmrated for br increasing the aoraq of the flew neasremuss
since the only Unit to +his is the external Iastr umnatiom.
In the actual se6..
the knife-edge is stationary and the boiling
analogy assembly slides over it.
Te position of the slide is recomed by
a micrameter head. Details of the fitting of the slide over the knife and
the seal obtained both against leakage to the atmosphere and across the
knife, are sboee in PIg. 6. ftrther details are given later.
- 6Keamameats of Flow Rates of the Two Phases
The to-phase mixtures issuing from the passage an the tw sides
of the knife pass directly into large chambers where the phases are
separated.
A system of baffles and stainless steel wool dissipates the
considerable mnerg of the strem.
Air collects in the upper part at the
chamber and is suyd through an orifice plate floameter to be ebausted
to the atsphere.
The air .zhaust system comprises a vacm cleaner whi h
maintains a suction in a pem
cylindr1.
Talves in the ducting to the exhaust system enable the pressures
in the chambers to be adjusted to aMshei before readings are take.
In this way leakage either between the chambers or to and from the atmphere is prevented.
The
amas are air-tight and all jouints are carefully
fitted with gaskets, nevertheless the method of equalising pressures Is an
added precaution helping to give one more measure of confidence in the
results.
Leakage between the chambers can only occur through the emai
clearance between the knife and the exit and of the passage.
This clearance
is adjsted to a few taandthe of an inch by a method desOribed later.
Since there is no presuare difference between the chambers saWay this
leakage may be neglected.
It only introduces a very slight statistical
fiuotwation which is not bised in favor of either chamber.
The..mai=
pressuue difference allowed between chambers was one mil4mter of water.
Air flow is measured by arifices of various sises chosen to fit the
particular requirements.
The orifices are of standard design and the
calibration curves are knowa.
Coparison between air flows measured in the
main air supply line and at these orifices showed excellent areemen6.
Pressure difference across the chaher metering orifices in
measured by a 100 centimeter vertical water anamter reading to one
millimter.
Chamber presawe in adjusted to atmospheric by bringing
the reading of a differential water mnamter to s.
A mass balance on the air flow is obtained by omparing rea&.
ings from the main supply line with those from the two chamber orifices.
The air line pressure is measured by a 300am mercury manoter and
pressure difference across the main orifice by a 300am water manomster.
Water flow is maeamwed by stainless steel V-motches end hoobgauges (Figs. 2 and 3).
lor very small flows a weighing teohoique is
used; this is the reason for the spouts placed below the notches.
The
water surface is sufficiently moothed by the baffles and stainlass
steel wool so that hook gauges can be read to one tmanmdth of an inah
under normal conditions.
Since the plexiglas may sag or distort with tme
nder stress or
as it absorbs water, the notch and hook gauge assembly is a separate castruction of channel steel which maintains its shape in any event.
As a
precaution, periodic checks of book gauge calibration were carried out
throughout the series of experiments.
No significant change was detected.
In fact, the hook can be reted more accurately than is warranted by the
weigh-backet method of calibration, slight flow changes due to surface
tension changes with temperature, ste.
Book gauges are shon in detail in Fig. 3.
The brass book is
screwed into a 3/.-inoh diameter steel rod which slides in holes in the
frame.
Readings are given by the micrometer head.
The micrometer tip
is soldered into a precision bearing which is the fixed point of the
.m8..
-ste. Mdustment is made by mean# of the 3 swus show
metering
umtii mstio Is qitt free in aU parts of the tavL.
epmpesla effects In the zed are negligblbe.
sanges
wae ---
11-ea
Se posmfoomnoe
shsrpened as
msede 1c heyand
m01ratel1 as
ith fae files. they are ooossicna1y emesved with a fila
possible
to
help prdeVat
w
morves for the motes
are sows
In protee, beoene of
flu, rates od the lsarp a
as am tawnO,
Pigs.
n
am
Calratiem
n.
inevitable f~meem
r of adjatsunts nesswy
d s to d the oorwes
In
the
befere agte-me seris an
it preyes better to aonseWte
mter netering ca
A
abme of the Jet to the emfae.
notch pe aning ieder 3e head is slum sn ftg. 2.
ibria
t these
thevmghat anl empeiamats.
The motcbes vw
of .il
esmil
ing air seres sMparatiy.
A phetograph of the whole apparatIs is
Ibaan F9g. 1, a vim
tom above with the slide assnmbly ramo3a ia Fig. 4
mad a shmtie
diag in Pig. 7.
It was a deminite admtage to ate the whole appaaates et
plezigdas since visal cheks Oaad essmr be mnde ow the finetioming
of aW part. Mh nate
of the flow past the knife eav3d also be seem.
-e restgaer test soticaM assembly fits in a slo both In
its baseplate and In the frme.
Befoe finally fixing the test seetica
to the basplate the whole assmb3r of ob-mbers .a
knife was built.4g.
Two thilmesses of mitable paper were the placed an the blade edge md
the test section lowered throgh the two slots
1atI
it rested an the paper.
- 9 Verticality and aligament were checked and the gluing of the test
Uem
section to its baseplate performed in situ with plastic oiment.
the oment dried and the paper was remved, the test section slid with
its proper clearance over the lnife-edge.
A crude, but effective, rack and pinion mechanism is used to
traverse the slide.
The mirometer head in for masuremt purposes
only and is not used to help nove the slide at any time.
In this 0a
the integrity of its readings in maintained.
Air Seal betwees Sid. and hamber Asembly
Details of the seal between the slide and the chamber asmbly
ce
soun In Pig. I.
The horisontal sliding surfaces of plexiglas ay
be :%pt wet or smearzed with grease in order to provide a perfect seal
againt air penetration, but this is a lu=ry.
Ie side of the slot in the plexiglas roof of the main assembly
is finishe' flat and serves as a guide for the slide.
The other side is
sealed by a etrip of gasket material as shaoun in the drawing.
The gasket
is stwk to the slide with glue.
It is easly seen that the only place where significant leakage
anald conceivably occur is in the clearance between the knife and the
sliding pieee and we hmve already stated that this is negligible.
As for perturbations in the main stream due to a possible sligh6
pressure difference between chambers, they are not biased in favor of eitbr
side and can be espected to average out.
evidence of ay such effect.
In fact, the resilts show no
- 10 -
In Fig. 6 is shown the knife and the 'scoop'.
The scoop was
i later refineent used to sample the middle section of the passage
nd eliminate the effect of water which rums dow the pleiglas sidewa:.ls and in the corners. The scoop results are nearer those which
woumd be obtained using a two-dimensional model ith the bronse walls
infinite in extent in the direction perpendicular to the direction at
flow.
L a nd Limitatns of the Al narats
1)
The soIdering teclque used to fit the bronse to the b'ass results
in som. soklor being absorbed by the bronse at the mds of the passage.
Ths the air does not enter imformVy over the last 1/2 of the carnel.
Large scale flow patterns will not be changed such by this fault, but
there is soen uncertaintr in the interpretation of results close to the
wall.
2)
Erosion of bronse and gasket material near the exit.
There is a
certain mount of flow dow between the brasse and the wall at the eit
due to erosion of a few bandredthes of an inch of the gasket.
also two or three charnl
There are
torn in the bronse noam 10 or 15 thousadths
of an inch deep and a little wider.
These should not carry an appreeiable
flow but may account for thin Jets of water seen passing the knife edge
iben it had already passed what was theoretically the end of its traverse.
..
nq..
3) Blooking of porons bemne pores by dirt In the air. A fIlter was
-- stalled in the air ite bat as
the same some partiAes of dirt ow
be em to hase amn lnt Me lU
-ke ratea .
bF pag
a
high premass
tse
man
m
dhimbesn and hae stonk to gh
de to wash ut dIrb In the ems
atw S a rewmese direetgWa to the aw=== aVe
2.4) A eahS
effect
presser drop neOr
n
hab ftaw rates mbihc remaits In a large
bt
aesit
a the passage.
air eaters at the lowae end th in
This mneo that mah me
the entaIse region.
come a point (I1g. 96) where aOst no air gets
2 fat tmere
s the first partae
the channel at all. Under these eaditions it Ls impossible to spedf
a babble generation rate indiaetive of the aotmal pieae
5) Plauiglas sa
ully distorts =uder the
inU
situatom.
nc, of stresses, water,
and internal stress-eeeving as a result of storing and cutting.
Eventully th baseplate of the Alide does not fit flat an its base.
This is only a sligt disdvantage for met purposes as it tus
cut but
it is nevertheless a wekess.
6) Too msW gauges which havie to be adjusted sanidtaeously, and at l0
flows a long time constant before steady conditions ae obtained.
Also,
some fl]ctuations ft water and air pressure which ooml4 not be entirely
damped oat. ftrik to get aroud those problems were developed as
familiarity with he apparats Increased.
7) Ass&7try In tie apparas. usfortuately, the physical iqaont at
present gives rise to assuastries In the flow pattern.
This can be
corrected by adjusting the air valves on each side, but is then only good
at one particular set of flow conditions.
Since there is no guarmatee that
in practice a boiler tube will be heated uniformly the assymmetry in this
apparatus is not so serious as might be supposed.
However, theoretical aalyses
are more easily performed when dealing with symmetrical flows.
-W12 -M
8)
A passage consisting of two NboilingU walls and two *insulated*
walls is not the best model for practical purposes.
The flow observed
is a kind of bybrid between what we should have for air addition on all
faces and for air addition at entry to the passage alone.
Nevertheless,
we observe phenoma which are initiated solely by the 'boiling8 faces
and by using the scoop rather than the knife, we try to minimise the
effectt of the plexiglas.
The weaknesses described above in 1) through 7) can be oerected
by improved design of the apparatus.
The last fault is inherent in as:
attempt to simlate a two-dimensional flow in a finite apparatus.
- 13 O
E6!
G 13
I
e.e of apeimats (Figs. 13-.m) was perfmd to
The first
invesApte "Is epaMlIttee of the aparaas nd to get som Idea at
the kind at resits to be emted.
ip.
13 and 14 shw water measurmmts for traverses ames
the adt pime of the passage.
All the air is fed into the inlet obamber
betore the passage siae we Iam hat kiM of flow to empeot for thes
, It Is In fhat an samalar flow
0di~
a
s shm
i
iiatims
ie
an air ores. Te
total flow during the eperimmab.
that the points define a smooth
my.
pe
It Is seem
and that fewer pidne are necessary
p ner regions of special iterest.
Tig. 15 shos an saprowsa to the above by plotng the ftraptm
of total f=m, rathser ta
the anlu-.
maUi
In this ow an greeks
..
are no..1edW to the same scale ad the varietiams in the total flow
beoome less signtitoant.
Fgs. 16 amd 17 show tan air traverses, nomlised, for the asm
outlet caMditaS
but In one case with all the air put In the mixing
chamber end in the oter case, all the air pamed in through the browse.
These graps tend to anerestImat
the ao
y with which air meamr
aebs can be ade sAnce at that time emperiame in rwining the appara
was small.
We can do several things with these graphs.
Fig. 18 sbows th
results of differentiating a pair of mormnalsed graphs for air amd water
flows. The result is a
distributin curve.
-
Aa
(vo
tri or gravinstric)
- 14 -
If we assume no slip betwemn the phases, we can divide the water
mas rate of flow by the total volume flow obtained by suming the air
and water cves, multiplied by suitable weighting factors, and obtain an
estimate of the water cncentration profile.
The scales of these graphs
are all proportional to the quantties stated above and my b converted
to absolute magnitudes if desired.
It should be stressed that since the flow is ver turbulent the
local velocities and oncmentrations change with tim and we only asrn
the tim-average values here. A mathematical analysis is given in
In Fig. 18 we also show the result of calclating X from Gand Ga
ourves.
The e ocentration of water at the wall is very noticeablIe.
In the set of graphs Pig. 18 the technique for obtaining the best
Curve was to nease the four slopes of the 3 curves at points equidistant
from the senter and to calculate a nea.
curve draWing is reduced.
.. ohis way some of the error in
This is all very well if the flow is substantially
Setrieal and is all right for the particular case here. In the general
ease, of ase,
only slopes at the particular mx are to be
ameared.
Fig. 19 shows the comparison of the results of differentiating the
graph in Figs. 16 and 17.
the to
The difference in mir velocity profiles under
conditions is clearly shoum.
Fig. 2D is a omparison of water flow uemi-profiles obtained by
differentiating Fig. 15.
With practice in reading the graphs it is easily possible to deduoe
the general character of air and water velocity direct fron F graphs.
415 -
Canclusion to Prelisdaarr Tests
lxperiusntal results are enouraging ad shw that the nethod has
a.e is very satisfaotory and an be imnered
proise. Accuracy obt
if desired.
antmserably
?he
flowS a,
seriA of graphs
,.
Th
i1s. 23.34 show f izhe
air and water intigrated
arm again of an emploratory natur and describe the effect
(as the air speed profile) of a steady increase In the water flow.
Air traverses ware taken first. These are shba
in Jigs. 21-30 and
olea3l sow for all sme a umiform vloecity in the canter of the strean
with a bomdary lqar
5
with +aman=
a fraction of the dir-umter flow rates.
She results are show differentiated and presented as velociy profme Is Jig. 31.
It is to be noted that the velanott beones steadiy nre
vimfemm the boa
y layer decreassag in se
strn is increased.
Amray
as the water fractica in the
near the walls is bad beoatse of the lowr flow
rates there.
These results are partcuLarly iopreesive in showing the large core
in whih the air speed is coustant.
Alsut withmt emseption the carves sh
a clearly defined lin.ea partion with epermental
In sam ftier
mpeinental LMatm
b
pointa falling deed a the
omly a portiem of the gph is dsou besm of
to the air flow distribUtms whch cod
be bandled
Me Yam cleaner aystm.
htee travees (Pigs. 32-)
of th sob el with oswaue
sides of te passage.
egeite
show agada a linear pertes in the
to that of the V.
ursis toninds b
enAr
-
16 -
Figs0 35-43 show further air and water traverses for which the air
flow rate is near the maximum obtainable with the present apparatus.
It
was hoped that these experiments would shed some light on the canditions
approaching burnout.
No noticeable or dramatic effects were observed, hw-
ever, except that the water appears to be concentrated more towards the sides
of the channel.
Air traverses, though they provide valuable information about the
overall velocity profiles, are not suitable for highlighting the various flow
regimes.
Furthermore, a greater accuracy is needed in order to probe the
most interesting region, that near the channel walls.
Flow Near the Walls
At this point we became particularly interested in the flow near the
bronse walls.
Since it appears that a uniform velocity and water concentration
area exists in the middle of the passage the changes in flow patterns will
probably be most marked in the regions near the walls.
If we kn-
the profiles
in these boundary areas we can simply join them up to each other with a
straight line apparently.
We are also keen to find son clue as to the nature
of the burnout process which is almost certainly accompanied by a deorease in
liquid concentration at the walla
To this end traverses were taken close to the wall for flows at
particularly low qualities.
Results are shown in Figs. 44-4.
tion of liquid at the wall is particularly pronounced.
The concentra-
It is especially
noticeable in Fig. 44 where the results for single phase flow of water are also
plotted.
Fig. 46 suggests the possibility of some new effect Just at the wall,
such as for example a sub-layer pc-
in water, which could indicate the onset
of flow conditions leading to burnout,
-17-
he vater flow distribaton near the vail in of psrtoular
Latewest =ad am be neasured accuratey.
- ee the nmet setom for a ne
relmits.
ori oel asessmnt of these
-18 DESCRIPTION OF EXPERIKNTS WITH THE SCOOP
Reasons for Changing to the Seoop
It was now realised that the relevance of the analogy (in its
form at that tine) to the model it was supposed to represent should be
re-exaained.
Nobody ever makes a rectangular boiling tube with pure insulan,
tion cn two sides.
This is what we have in the present analogy.
We
should prefer to eliminate (or at least minimise) the effect of the
plexiglas walls.
A visual observation of the flow leaving the passage shows that
a noticeable fraction of the water runs doum the plexiglas and in the
corner between bronse and plexiglas. In fact, the flow we want to
measure, that in the channel center, is obscured in our measurements
so far by the effect of the superposed flow down the walls.
From our
measurements we can only say that the layer on the plexiglas is thin
since it will be of the same order of magnitude thickness as the layer
on the other wells presumably.
NaB,
The air velocity profile is not obscured in any important way by
this effect so that the knife in its present form is good enough for air
traverses.
To get over this problem the scoop shown in Fig. 6 was designed
for use in place of the knife.
It performs the same function essentially
as did the straight edge but it now samples only the middle 0.400 inches
of the stream and avoids the layers on the walls. It is not good for
measuring air flows since the seal between the ambers was designed for
- 19 the straight knife and clearanCes are not so close now.
Pressures are
still be1enced betbeen chaubers so that negligible foraes act to divert
the water phase, which has cainerable momenton amuewy.
A few experiments showed that results for water flow with the
scoop were far more realistic than those taken using the straigh6 knife.
A traverse (Fig. 49) under conditions of hullydeveloped .a..a
flow
shows en almost sero water coneentration in the channl center (shorn as
sero slope an the graph).
By successfully subtracting the obscuring
effects of the plexiglas we have succeeded in highlighting the main stream
conditions and approaching the ideal which would be a measure of flow
distribution
in a ohannel of infinite width, the effect of the plexiglas
faces having been reduced to sero by pushing then far am .
A traverse in the scoop case is slightly longer than in the case
of the straight edge since the scoop edge is not trWly parallel to the
bronse faoe.
Since we are differentiating to get results this effect is
of miner import..ce.
We are simply measuring the average flow over SonM
0.010 inches aentered at t& instead of the fiw itself at x' ad the only
sigifloat errer is caused at the walls or close to then where the scoop
is at Its 3east effective as an acinrate sampling device sewe.
With the development of the scoop it was felt that a flller and nore
systematic exploratom of the range of flow obtainable was tinely. The
series shown in Pigs. 51-99 is typical of what happens when the air flow is
increased in steps, keeping the water flow rate constant. The graphs are
shom differentiated in Vig. 60.
-20-
The dotted line across the graphs shows the fraction of the
total water flow which is captured by the scoop.
There is some
correlation between this and the flow patterns, at will be seen.
The general sequence of flow regime is al follows:
With no air flow the water has the usual parabolic velocit y
distribution.
As air flow is increased the water flew down the center of the
passage increases at the expanse of the walls.
larly clear in the next series Fig.
This effect is partiou.-
6148. This is thought to be
partially due to the increased visoosity of the bnbbly layer at the
wall.
On further increase of the air flow the distribution becaes
parabolic again and soon the linear center portion became more noticeable.
A transition point is reached where the concentration at
sudeny increases considerably.
we
This is accompanied by a more violent -
noise at exit to the passage, sonething like a roar, compared with the
sott sound of bursting babbles in a frothy liquid which was observed
previously.
After passing through the transition region the flow adjusts to a
double,-humped distribution which strongly suggests the annular flow folnd
before.
As in the case of Fig. 18, the curve of actual water concentration
is far more vivid in showing this effect end it should be borne in mind
that the height of the peak at the wall will be many times the level in the
passage center if we plot such a curve.
lar,.
Rather then increase the already
number of graphs presented, this re-presentation is left to the resaer.
- 21 As air flow is fwther
incresed the profile toads to become
more nifom agIn. Noise level increses steadily as more air is
14rther traverses (Pig. 61-6) were taken in an effort to ap
the area of the first transitin region.
defined
This region is not very vWml
oept at iom water flow rates since its debermlaadem depends
an our being .abLe to .lasity a particular flow as being of me kInd or
In fact at hg rates of water flow the tranimtan, a
another.
lr
ad uniforA ftiw regions become ae and more indiutInguishable.
The general area of the treaitios
region is show In Fig. 90
uiich enmariueu the laswfication of flows in this seiels.
This experiMt was the most satisfactory CUe of the series.
We have sIceeded In apping tree district fiew regimes wbieh
will later be identified as"bb,trasion,
and inlawr.
ftrther quantitative results for the magitude of the obhages in
flew paterns may be obtained by the methods indicated.
Silted
-unwt Exeaffan
With
e bunout problem still In mind it was decided to investIgate
flows at the 2a1smm air capacity of the system.
Th Griffith correlation
(ref.2) gives an estIate for the water flow rates of ligres U7 thra S9, af
arond ll oubte feet per minute of air at atmospheric pressre
spplied
uniformly dowa the passage to bring about an approach to barnab camdiimmh.
.. 22 ..
this figure of 1laft may be inalcnrate br a fastor
At Ach low premes
of 2 or s,
-of
so there is no guarantee er sneess, especially in a boama
suai oross-es-tin. Abmot the mnutn
air flow ob+.simbh1 ith this
apparatOs is 33ebs. Resmats of traverees are shmm in ligs. 67..
ater
news
eem be -eaamee
as accurately asdesires
a weighing the flw over
patimo. peats, by mting for equaineiw
3emg peitoss. The e
-d as
amaties er Water into the ar is nwt 4sitteeinmt
here since am. the water beems vapor it bebees an the gas phase in the
ohwna4
we are euly interested in the distribution of water which
remins is the ligata phase.
Ih nifora distag- batioa of flow rate is v7
marked over the
Fig. 89 is a partclulary good .mpa.
greter part of the oen.
is sti1l a fil1 at the wall mih
is enneniuably .a.naed
There
by drops stice-
Iag to Oe wUl.
In sue oases, a strange effet ocars at ts left bas well. In
Ig. as sefsal potats on
a readings 1a
the
lhe
inear
eft bad side she
0 a0
may ndate
s= t
= 60W
en instability akin to bemmxs.
p is lost, there
appears to be a
im ao air
heisting potat, ate. anG was a
of
fompres
frm the wal is srioiint
-ater
on the
(this rn
eapability, pressure 32e
repeated.)
the medsa fm am& a case is preambly
ee,
-Aert-e
In Pig. 67
ould be stempreted as a ease of '-roma".
ow ae at the accohM
in the strm
, abow mltiple values t
that the velocity of air auw
to blaw te drops, *hi&h hae
may fsm the w l l idt u a
belenS velocities
ffn mt- ftrce to preeat the
gttag trogh to te wall itme.e. Bub a adal seem rmam1
bawasut pimmammam t the bigqwplig,
Is. pressure ang.
aeeurate ezperlmemts are needed to confirm or dispro w this.
fr th
ore detaed and
- 23 We thus add the final regim, to the set; drop-vise flov of water
Ia a strean of air.
Cog~anoson on -the 3h=3late
BMrWa jxermenta
A remI- malw nodel for the approach to bumout at high qualities
sesto hane been found, it is thim
At high boiling rates the turbulent mticn of the water drops In the
ant stream is Iufficient to support the water film wbich rms down the wall
and is being contianl y dqleted by evaporation and by being blom. off" the
wall. Bkrammt Oditima reault.
rates the burnout regian seems to be preceeded
Note that at all f3
by a flour reges Ia which both phases are uIformiy dietributed across the
eseal.
These
seoop is not
pimats are not calete without a dimnstration that the
finhmalag the flow distribatAn In the eit plane and aking
the readings sunr=4=a-i
TO this end the scoop was turned and three flow
distrbutions hebeked with the reversed soap.
Zhese are ehen Sn ias.
8s, 82, mad
S,
sA, 82A, and N,
whih cheek with Figs.
espetivly. Of oore, the readings have to be refleeted
before plottiag.
The
w
right hand well of Wig.
S is oheoked by
ig. SOA. The rest ot the crve is nob very good because of large obus
in the water fle rate, uovever the masn polat has been ohecked umtfieit3a.
-- 24 -
Pim0GRA
0?
OF L0f PATITMS
A further technique possible with this apparatus Is to p
the fin
Wsing a highb-peed flash.
g
The various flw pattenrs are Wel
defined and provide a very usel check on the previous lsperiment.
few photographs of a sIa
A
type have been taken by Di Saes (ref.l).
The photographs provide essentially a measure of the attauation
of light rays in passing through the flowing mixture.
In the experimental
set-up the flash, ground glass screem, test section, and canera are
arranged in a straight lime.
The flash gives an intens. pulse of light
lasting 2 microseconds and this is sufficient to obtain instantaneus
pictures of the flow.
In spite of the ptarabolio reflector behind the
flash and the grond glass screen in front of it,
tesw-section is not quite uniform.
the ilm=ination of the
All the pictures turn out to be brighter
in the center, bet all the same the general flow characteristics are usms13y
olearly visible for the whole length of the passage.
Photographs were taken with camera settings from fS to f321
aperture vals being chosen to give optima detail on the negatives,
the
f8
represents the upper limit since for this valUe the depth of focus besones
insuffioient to view the whole flour clearly.
There is also the distortion
of the Image by the p3eiglas to be considered at the ends of the section.
This is the same as the vefll-nous effect whereby the bottom of a swimming-.
pool appears to rise away from the side of the pool until it f1naW3'
water surface.
hits the
A pair of phtographs wae takui at each setting to obtain an
tinate of how steady the flou patters were with time.
It aobwad be stressod that the brightness of maccessive photo.
graphs is not a masenr of the relative attmation of the light rg
xposure time are cboen
sines both the camra aperture ad the printing
fbr ea& pioture separately to
th local contrast as well as
Vihasise
possible.
S..ples of photographs are ahien in
"babbl' to aiAmn
r
nigs.
91.9n.
The te.ad from
mad finally to a more niforu streaky' flou at bigh
quanities is clear.
Desemm
of Zia Pten
this fl
pattern (or flow reAgas) consists of air babbles of all
sises ith the Itersttces filled with water.
A aose inspection of the
pictwes shows that my more babbs near the walls and in same oases
these appear atached to a point n the wall, pres
ae. The distribtil
Jably a %nuleation
of the two phases looks fairly uifom aroes the
chamel. A speetal mlarg- int of the bubbly £lov regime is abown in
this regime is Jt
bubbly to =mar flow.
nig.97.
what Migt be expeed from a transition froe
It Is a Iqbrid of the twe forms.
- 26 --
EssntiMally this regise onasists of a core of air, which may
contain sos water In the fam of drops, suwrumded by bubbly layes an
the broose walls. The pattera is not at all steady and In places the
are bridges of b*Uls which appear to spam the channe1, althaugh these
3ay be only one or two layes thick on the side wall.
the bubbly 1ayer
ca the bromse walls eperiences heavy shear stresses from the high speed
air stream In the oear and is eseited to fora surface waves, some of which
develop Into orests and appear to be being torn off to fors droplets which
are then earried alcng In the core.
As air flew rates, and hnee flowing speeds, are Increased he
.
ar flr gives way to a new regine. The photographs show a rather
unntelligible sist of varying opasity which it is thought might be due
to a flaw pattern In which the water In the strean is In the form of drops
suirliug arnim
babbl
with eaceenly turbulent velocities.
present but they will be very small since a
apart by the Intense shear stresses.
tendeney to
There ay be some
large ones are torn
This model would acolt for the
itforz water fler rate aeroses the channel at high flowing
velocities *bmud In previous traverse eperints.
At eer high air flaw rates the pattern is flrther obsreg tw
shear stresses actIng on the liquid layer an the plexiglas. A nlargeunt
of this kind of flew is shown In PIg. 97.
-m273 Cahine
Ifeots
For high rates of water flow a "hokingN
effect, simiar to that
obsved for flashing flow of hot liquids, gives rise to high prno
gradints near the soit so that only a small proportion of the air am
get in at the beginning of the passage (see Fig. 96).
9asnUnt a
,1
amanit
(se night expect the local flow regime to be a faotion
the flow rates of the two phases.
of
aainly
This would sean that we should have the
am series of flow patters aMting up the passage as we increase the air
flow rates from the siAmIas- lbr meaple, we should have the sas flw.ing rates of air and water and preumb3y the same flow regime about 1/2 the
way up picture C of Fig. 91 as at the eit
of picture B.
tbfortunately, such a oorrelation does not suoced at all. Picture a
appears nearly all inlar
whereas picture B is certainly hubbly.
The flow
regime seems in gensial to be determined more by the rate of babble faatiu
at the wall (i.e. the stealated bolitag rate) than by either the flaing
quality or the legth along the passage in which the friw has had time to
It sbani be bonne in mind that a photograph does not sho all features
of the the-
m
ma flow.
For amanple, an s=13
--
core will not be
visible it it is behind a row of hobbles ca the pleaiglas wall.
An attuqat to classify the pictures representing
and
abubbg, transition,
=la flows resulted in transition lines at higher qualities than those
aboum in ftig. 90.
This is partly &e to the fact that the photograph does
eacted to the full length of the chmanl (co
t
and one-half inches or so abort)
and partly due to the shielding effect described above.
- 28 -
The photographs show one thing that the previous traverses osanot
hope to showe
the variation of flow patterns along the length of the
passage.
Suppemetaryi l4otofrachio
eRosssets
A forther series of photographs was taken with all the air being
introduced at the top and of the passage.
The results are not partiwmlarly
relevant to the present report but the pictures are available at NLI.T.
should interest in this type of flow arise.
1)
Changes in the distribution of the liquid and vapor acros theahannel
correspond to changes in the flow configuration suchgram bubbly to eawra
or drapemflove
2)
The distribution of liquid and vapor across the chan1 and the flow
regine is arkedly altered if the vapor is generated at the walls instead
of passing i th liquid dow the cbanel for the same apparent flowing
conditions.
3) No slug flow regime develops when the vapor enters at the walls at a
sufficiently high rate.
4) So striking change in flow regime is detected in passing through a
simlated buruout.
5) At large rates of vapor formation at the walls, the flow regime appears
to be mor dep ndnt on the rate of vapor formation then either flowing
quality or local velocity.
-- 29 ..
IMatpA9oaL DsrideM of theAnlr
The mathma oal descipliot
used here is eztreme
aipl.#
por a boiler tabe we have the appraxmate relatioM (which is
accurate if the pressue drop in the tube is emal):
Volisee
additica to flow per unit lngth =
For the naloga
Tobame Adition to flee per ift lengh = T.
lbr u10de ooMParisons we equate the above quantities and writes
since steam ad air prapetes are comparable at atspherio pressure.
The maiA flow characterislis are a result of the interacton of
the light gas with the heavy liquid and are determined primariuy by the
imma=e deuit difference.
Thas we do not expect sigificant errors by
replaing stem by air.
g does not take aocut of the loss of water mass when
Th aSna
steam is fotmed.
At lM pressures Mis effect is negligible.
Of orse a mre asedete analyuis is possible.
parameters m
imensionless
be inIIsA. which take acont of the difference in
properties of steam and air, of the bramse and a boiling surfae.
&eh
a development is cassidued premature in this report which is more a
descriptio
of techniques and of the kind of results obtainable then an
exhaustive investgation.
.- 30 -
APPERIX
l symbols we have:
In na+mtmA
= water flow fraction up to distanc z
f,(x)
()
-~
s(z)
=
air flow fraction up to dista
z
water fnew cu.ft.per in.
ou.ft.per min.
total air flow
=with of pass.
t = tal
Q=
D
Wene the resultst
f,(D)
= fa(D) = 1
U
ax
a
a
Ox
rate at water flow at Z
= rate of air flow at z
I a+
az
= total
dx
voeI2
rate of flo
at x.
For no slips
Water cameontration i
t
dr +
a
In met oases
Q,<G
."
4
and the streaw velooity profile nq be taken
an the m" as the air flaw profll@, eoept close to the wall where there is
usualwg a laer rich in water.
-W31-
Pig. (1) of a report by P. Griffith, 'The Correlation of Nulate
Boiling Biunot Data* (ref. 2) shows burnout points plotted on a graph
41.5 (9)
(I -bg
where P/'
4-1
is the ratio of stream prese
to the critical prese.
For the analogy we estimated P/P, = 0.005 giving an ordinate oe
arond 500.
(h-ht) is replaced by
7
4
1(l
)
is given by Appendix A.
The rest of the variables are taken as the corresponding values
for air and water where appropriate.
The result Ist
for bnurout (M OW 10.7 (1
-,)
a. ft/mdn
so32
as
V-" ?-1-9 4-
Lumfth 100o brola wile 040'D wide, 0.0o20' gaekot, mosumc at
vidt 0.542 X 0.250'.
Chryser OsApArtOm Dtzitl RFoh~go
flltemd
Sis. reo at part~l"e
om.feui da ome brouse 300 Ina as of water
S-12U
at f13 zates of 2 o.f.,m/qSa.
Mdth 00',8 sma3ag
bier of omu
hAUO CC 940P area to faul 01om
~obe tqpe
Iap. Liin a
o50-
area, 0.74.
bof Wby
Oel ShaoCbip
ofJtaiy llgt flaeh of 2 uiozroeeod dME-=m
33 -
-
-LTST
Description of _oarataae
Figs.
1-s
ngs. 11-12
Photographs and diagrams.
Hook gauge calibratio
curees.
C
Figs. 13-14
ater traverses, all air added in mizing chahber before flow
passage, water flow rate as ordinate.
pig.
15
Series of water traverses as in 13,14.
Fractioa1 flow rate
as ordinate.
Fig.
16
Air traverse.
Fig.
17
As 16.
Fig.
18
Water and air flow rate profiles for Fige.15,16.
7ig. 19
ig.1 20
Figs. 21-30
ig.
31
igs. 32-34
Air added in mixing chamber.
Air added through bronse walls to aiinilate boliing.
Comparisn of air f2ow semi-profiles for Figs. 16,17.
Water flow se.Lprofiles for Fig. 15.
Air traverM
Air flow profiles for Figs. 21-30.
Water traverses corresponding to Fgs. 24,25,30.
Figs. 35-40
Air traverses for high air flow rates.
ngs.
Water traverses for high air flow rates.
Figs.
4L-43
Detailed water traverses elose to wall for high air flow rates.
SiMIlated BoilIUn
oeiamnts RBain 80o00
Air added in sliing chamber.
Figs. 49-50
Preliminary Tests.
FIgs. 51-59
Water traverses with simlated boiling.
Water flow canstant,
air flow varied.
Fig.
60
Figs. 61-86
Figs. 8749
Water flow profiles for Figs. 51-59.
water traverses.
mal ated burnout experiamts.
Water traverses.
Figs. 90
Flow regies deduced from Figs. 49-9.
Figs. 91-97
Photographs of flow patterns.
page in all cases.
Flow downvards from top of
Air added through broanse.
4w33 -
This wf hs bom eftt"Iwy mjprtdby the Ofioe at lavi
hseaoh a
hasbornp.fo=*d isth. bat Trmsfw Lebyabotoc'tth
Nsa I ette I pm i 6 s b of
so1@mo, uwb s mda' the msmwvIsa
2) *Flow balms In a Toha DuIM3g MW oU'
1. 0. ft. Sama
LI.?. SL thesis l958
2)
'iOftlato of N
P. WItfth
Wclatehlu amut Dataus
A.8.l3. Papa No. 574T-41.~
pF
'710
-i
MMM
-;
1-
fC)
LL
c-l
C)4
~~A1
11=101hldlki
I 11'''ildill"i
200 psi Air
I
City
Water
Fi Lter
Exhaust
t
Test
top
Section
I Air to sides
Position P of
T/S Measured by
Micrometer head
APR
-
-----
Water
rator
water
b--
hR
air
Left hand half of system
not shown on drawing. It is
identical with the right
hand half.
FIG.7
SCHEMATIC
SYSTEM
DIAGRAM
Brass
Porous
Bronze
- Flow Channel
Gasket
Glued
Joint
Slide Base-plo
'acking
Soldefed Joi
lexiglas of Frame
Knife Blad
II
I I
II
II
II
I
SECTIONAL VIEWS OF KNIFE ARRANGEMENT
SCALE', FULL SIZE
AIR SEAL
FI GUR E 8
No bolt s ,nuts or screws shown.
PAGES (S) MISSING FROM ORIGINAL
Figure 9 ?
PAGES (S) MISSING FROM ORIGINAL
Figure 10
1.0
0.8
u0.8
.C
C
0
C
: 0.6
0
0
o.40.6
z
0.
0
0
0
0
0.4
0.4
0.2
0.2
0
0
2
6
10
14
18
Water Flow lbs. /min.
FIG. I1
22
26
2
6
10
14
Water Flow lbs /min.
FIG. 12
18
22
26
09
007
09
d
00E
09
02
09
00t
d
09
00E
09
002
9
9?
9
9
0
01
0
M
01 M
100
100
80
80
60
60
Fa
40
40
20
200
60
60
P
FIG. 15
300
400
60
P
Air in Top Only
FIG. 16
100
40
36
32
80
28
24
60
G 20
40
16
12
20
8
4
0
0
200
Air in Sides Only
FIG. 17
60
60
300
FIG. 18
400
40
36-
32-
28-
24-
Go
20-
16-
12-
8-
400
200
60
300
P
FIG.
60
600
60
200
60
300
P
FIG. 20
60
400
70
60
50
40
30
20
10
0
340
400
40
500
360
400
40
p
FIG. 22
FIG. 21
60
QO
500
= 3.7
Qw = 0. 182
5040
Fa
Fa
-
30F
20
0
360
400
p
FIG. 23
40
500
340
400
40
p
FIG. 24
500
30
10
0
340
400
40
340
500
40
500
400
40
p
FIG. 28
500
400
FIG. 26
FIG. 25
70
70
50
50
F0
a
30
30
10
340
400
FIG. 27
40
500
340
009
I
O
02 'd4
d
0017
I
I
I
/
017
009
O0
d
0017
/
/
A0
/
0VE9
/
0
01
-/
09
08'0 = MO
9,9=
=O
Do
II2r
I
'
OIL
I
I
I
02.
I
I
02.
I
OL
009
I I
Ot?
I
I
009
I
I
d
Ot,
I
I
0ot
I
I
OtE
I
I
7,
09
Ot,
02
d
00#t
08
09
OVE
Ot
91
02
Do
09
981'0
-
08
M
o
/
-
0o1
001
80
60
F,
40
20
0
340
400
40
500
40
600
340
400
40
p
500
40
600
p
FIG. 33
FIG. 34
100
0, =1166
0,= 0 352/
-
80
60
F.
40
-/20
-
0
340
400
40
P
FIG. 35
500
40
80
340
400
40
P
FIG. 36
500
40
80
I
i
I II I
i
Qa = 9.8
Q = 0.41I
. = 10
Qw = 0.112
50H
30 I-
30 K-
1o -
101,
1
1
1
400
40
P
FIG. 37
340
I
I ,
340
1
500
I
I
I
400
I
40
500
FIG. 38
70
|||
Q =10
Q. = 12.6
Qw = 0.688
Qw = 0.198
50
50
30
30
/
/
10-
10
/
340
400
P
FIG. 39
40
500
I I
I I /l
400
340
I
I
40
FIG. 40
I
500
009
Ot,
£17 'OHz
0ot
Ot7E
009
Zt7 'E)1
Ot,
0ot
09
017
It,
*9 11
d
009
Ot'
QOt'
0t7
O012
11'.
20-
6 -
2
10
6
2
540
560
580
FIG. 44
600
22
18 -
14-
10
6
270
540
600
p
FIG. 45
26 -
22
20018w
14-
10 -
6 -
2540
60
80
P
FIG. 46
-
600
mull.
26
22
18-
14-
10-
6
2
540
60
80
600
80
600
FIG. 47
26
22
18
14
10
6
2
40
60
P
FIG. 48
Iu
I
I
I
I
I
I
10
Q.= 4 95
Qa
Q,= 0 221
Q=0 234
80-
80
60-
40
I
!
il
II
I
40-
20-
20
n
600
40
700
40
P
FIG. 49
AIR IN TOP
800
50
600
40
40
700
P
FIG. 50
AIR IN TOP
800
|
|
600
|
|
40
|
|
| I
I
40
700
P
FIG. 51
I
I
I
800
I
100
100
|
I|
I
|I
I |
I
I
00 = 2.4
Q= 2.21
Q. =0.232
Q,= 0.233
80-
80-
60
60-
NF,
40-
40-
20-
20-
I
10 0
i
i
i
i
IQ
I
40
700
P
FIG. 52
40
600
i
i
1
0
01
i
i
I
I
i
1
1
1
600
800
1
I
I
l
1
i
800
40
700
P
FIG.53
40
I
00
Q0 = 2.49
0, = 0 230
= 3.23
Q, = 0.230
80-
80
60-
-- -----------------
60-------
Fw
w
40-
40 -
-
20
20-
0
600
40
40
700
P
FIG. 54
800
600
40
700
P
1G. 55
40
800
100
80
60
w
40
20
0
600
40
700
40
p
FIG. 56
800
p
FIG. 57
100
100
Q. = 9.2
0,= 14.0
Qw = 0.234
Qw= 0.237
80
80
601
60
40
40
20
201
-- -
600
40
700
p
FIG. 58
40
800
-
600
-
-
40
-
-
-
-
700
FIG. 59
-
40
----
800
Qo =2.4
Q, =2.21
Q,
I
I
I
I
I
Q,= 2.49
Q,=0. 230
Q,
=0.232
=0.233
I
Q.= 3.23
Q= 0.2 30
Qa
=9.2
Q, =0.234
P
FIG. 60
-
0, = 3.90
Q, = 0.234
Qo =14.0
Q,
= 0.237
100
100
0 = 0.75
Q. = 0.62
Q0 =0
Q, 0.620
80-
80 ----------------------------------
60-
60-
w
Fw
40-
40-
20-
20-
0
0
600
10 0
40
|
|
|
700
P
FIG. 61
40
|
1
1
800
|
|
600
700
P
FIG. 62
40
1|
1
0, = 1 10
,= 0.62
40
800
1
1
Q0 = 2,3
Qw = 0.60
80-
80
60-
60-
w
F,
40-
40-
20-
20-
o
|
600
40
700
40
P
FIG. 63
|
800
0
L
600
I
40
I
I I I
700
40
P
FIG. 64
I
I
1
800
1.
.
l
I
i I
I
I
I
I
I
I
I
l
Qo = 3,6
Q,=0.60
80-
5O-
40--
20-
0
Ii
I1L
I LI
600
40
700
P
FIG. 65
40
i
800
FIG. 66
11|
1111I
|
|
|
|
0. = 14.0
Q, = 0.60
80b
- -
-
-
-
-
-
-
-
-
-
-
-
-
-
40
20
600
40
700
P
FIG. 67
40
800
600
40
700
P
1G. 68
40
800
-
100
Qo = 2.5
Q, = 0. 365
801
401
201
- - - - - - - - -----
I
I
600
I
40
I
r
I I I I
700
40
P
FIG. 69
I
1 1
1
10 01
1 11
800
600
40
700
P
FIG. 70
600
40
700
40
800
40
800
1 1
Q, =4.0
Qw = 0.357
80-
60-
-
w
40-
20-
O
I
I
I
600
I
40
|
[
l
700
P
FIG. 71
40
800
FIG. 72
11
00
1
001
1
1
1
1
Q. = 1.75
Oa = 1.6
Q, =0 088
Q. =0.077
80-
80-
60-
60-
40-
40-
20-
20-
0
0
600
40
700
P
FIG.73
40
800
100
I I
F
100
600
40
I
700
P
FIG. 74
I
40
800
I
Q, = 2 8
Qa = 2.2
Q. = 0.085
Q = 0.089
80
80-
60
60-
F,<
.
40
40-
20
20 -
0
0
600
40
700
P
FIG.75
40
800
600
40
700
P
FIG. 76
40
800
1
Q, =3.18
Qo = 5.55
Q, =0.091
Qw = 0.088
801-
801
-
--
-
-
-
-
-
-
-
-
-
-
-
- 601-
60
40
2040
20
600
40
700
P
FIG.77
40
600
800
40
700
40
P
FIG.78
1001
800
1- I
I
I
I
-
-
Q =2 12
= 0.154
Q
80
- - -
-
-
-
-
-
-
-
-
-
-
-
- --
40
20
600
P
FIG. 79
40
700
P
FIG. 80
40
800
50
I11,
j
100
I
|
|
I
|
I
|
|
I
I
I
|
I
Q, = 2.42
0 = 0. 141
80Qa =2.40
Ow =0. 1 2
60 Fw
40-
P
FIG.81A
SCOOP REVERSED
20-
0
40
600
I|
i
10 0
|
700
P
FIG. 81
40
|
|
800
|
|
Q =2.81
Q. =0.125
-
80-
Qo =2c
60-
0.
F
40-
20 -
|
|
|
|
|
|
P
FIG. 82 A
SCOOP REVERSED
0
600
40
40
700
P
FIG.82
800
100
100
Qa = 3.06
Qw = 0.44
80
80
60
60
1
-
40
1
11
l
i
20
.
600
40
700
40
800
600
40
700
40
800
p
FIG. 84
FIG.83
100
Inn
I I
I
II
I
I
I
I
I
I I
I
Qo = 13.5
Q,= 0.131
801
--
-
-
-
-
-
--
-
-
-
-
-
601
40
20
600
40
700
FIG.85
40
800
600
40
700
FIG. 86
40
800
-
69 01
09
009
9891AI
Ot,
0OL
Ot'
009
|
0
008
|
|
l| i|
d
0OL
i
J
Ot 009
il|l|
|
Ot,01 "o
0.t, I='0
0 21 = Do
I
Ot,
-C
910,0 =M0
II
I
I
I
I
I
I
n I
I I
I
I I
III
I I
I
I
I
nn
14
I
U
II
I
I
I
x Bubbly flow
121- A
0
0
a
10
Transition region
Annular flow
Simulated burnout
points (dropwise flow)
8-Qa
6F-
410
D501
x
G
2H
x
x
0.1
0.2
0.3
0.4
FIG. 90
0.5
0.6
0.7
A
B
C
D
F
G
Q,(cfm)
0.040
0.040
0.040
0.038
0.038
0.b 8
0.035
Qa(cfm)
0. 42
0.94
1.83
2.56
3.56
4.8
7.12
FIGURE 91
PHOTOGRAPHS OF FLOW PATTERNS.
H
0.035
13.0
S-
p
-a
-II
C
Qw(cfra)
0.075
0.074
0.074
0.070
Q (cfm)
0.72
1.45
3.6
6.8
FIGURE 92
0.067
12.1
A
B
0. 155
1.52
Q,(cfa) 0. 155
Qa(c fa) 0.95
FIGURE 93
C
D
E
F
0. 146
7. 67
o.150
0. 149
0. 150
2. 65
3.96
5.20
G
0.144
11.3
-4
t 0)O
-10
to
OH
a0
a
U
N
O
O
O
O
H
H
rA
-4
O
0
C
C4
Ol
8
c4
00
RO"A
O
4400
BUBBLY
FIG.97
STREAKY
ANNULAR
TYPICAL
FLOW
REGIMES