LAMS-3070

C3t

CXC-14REPORTCXXLECTION

REPRODUCTION

COPY

LOS ALAMOS SCIENTIFIC LABORATORY

OF THEUNIVERSITYOF CALIFORNIA o LOS Al-AMOS NEW MEXICO

PRESSURE OSCILLATIONS INDUCED BY

FORCED CONVECTION HEAT TRANSFER TO

TWO PHASE AND SUPERCRITICAL HYDROGEN

PRELIMINARY EXPERIMENTS
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LAMS-3070

UC-34, PHYSICS

TID-4500 (29thEd.)

LOS ALAMOS SCIENTIFIC LABORATORY

OF THE UNIVERSITYOF CALIFORNIA LOS ALAMOS NEW MEXICO

REPORT WRITTEN: February 1964

REPORT DISTRIBUTED: May 22, 1964

PRESSURE OSCILLATIONS INDUCED BY

FORCED CONVECTION HEAT TRANSFER TO

TWO PHASE AND SUPERCRITICAL HYDROGEN

PRELIMINARY EXPERIMENTS

by

Rodney S. Thurston

ContractW-7405-ENG. 36 withthe U. S. Atomic Energy Commission

All LAMS reports are informal documents, usually prepared for a special purpese and primarfly prepared for use wltbin the Laboratory rather than for

general distribution. This repert has net been edited, reviewed, or verified

for accuracy.All LAMS reports e.xpresa the views of the authors as of the

time they wem written and do net necessarily reflect the opinions of the Los

Alamoe Scientific Laboratory or the final opinfon of the authors on the subject.

ABSTRACT

Pressure oscillations induced by forced convection heat transfer

to liquid hydrogen have been probed using a preliminary apparatus which

cooled from ambient to LH2 temperatures during each run. Acoustic modes

due to Helmholtz and open-open pipe resonances were observed at sub and

supercritical pressures. These oscillations did not develop when the

inlet hydrogen was superheated. Pressure fluctuations in the form of

sawteeth, negative pulses, and beats were also observed above and below

the critical pressure. A mode which primarily occurred above the critical pressure and one associated with

also observed. Experimental evidence

was substantially better in two phase

at low flow rates, that pressure drop

subcritical two phase flow were

also indicated that heat transfer

flow than in supercritical flow

increased after the apparatus

had cooled near LH2 temperatures at moderate flow rates, and that greater

axial temperature gradients were obtained in the slower cooldowns.

iii

ACKNOWLEDGMENTS

This work has been undertaken as part of a doctoral dissertation for

the University of New Mexico. Chairman of the dissertation committee is

Professor V. J. Skoglund; additional campus members are Professors

M. W. Wildin and G. A. h!han; and the Los Alamos advisors are Drs.

J. D. Rogers and W. L. Sibbitt. The use of a preliminary apparatus was

suggested by Dr. Rogers and my group leader, Dr. J. E. Perry, Jr. I

was instructed and assisted in the use of liquid hydrogen flow facilities

by Drs. J. R. Bartlit and K. D. Williamson of CMF-9. The electronic

installations were directed by W. Willis of CMF-9. I am particularly

indebted to J. C. Bronson and the staff of technicians at CMF-g, whose

skill and experience were employed to solve a number of practical problems aitd make my apparatus workable for cryo~enic experiments.

!

v

TABLE OF CONTENTS

Page No.

Abstract iii

Acknowledgments v

Nomenclature

1. Introduction

1.1 Purpose

1.2 Definitions

1.3 Previous Experiments

1.4 Objectives of Preliminary Experiments

II. Apparatus

2.1 Overall System

?.2 Test Section

2.3 Instrumentation

2.4 Experimental Difficulties

111. Results

3.1 Results from Nitrogen

3.2 Observed Oscillations in Hydrogen

3.3 Cooldown Histories

October 11

October 14

October 16

October 18

October 22

October 23

October 24

October 30

November 6, 7, 8, and 13

IV. Conclusions

4.1 Pressure Oscillations

4.2 Cooldown Phenomena

4.3 Instrumentation

xi

1

1

1

3

4

6

6

7

8

9

12

12

13

15

16

18

19

20

22

22

24

24

25

27

27

30

32

Bibliography

vii

33
1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21 ●

LIST OF FIGURES

Page

Cryogenic Flow System. 34

Test Section Details. 35

Pipe Resonance in Nitrogen. 36

Outlet Plenum Volume Effects on Helmholtz Resonance in

Nitrogen. 37

Superposition of Pipe and Helmholtz Resonances in Hydrogen. 38

Sawtooth and Negative Pulse Phenomena in Hydrogen.

Negative Pressure Pulses Accompanying a Rise in Inlet

Temperature at Supercritical Pressures.

Pressure Beats Accompanying a Two Degree Rise in Inlet

Temperature at Supercritical Pressures.

Dependence of Pressure Oscillations on Inlet Conditions.

Pressures, Temperatures, Amplitudes - October 11, 1963.

Frequencies - October 11, 1963.

Axial Wall Temperatures - October 11, 1963.

Flow Rate - October 11, 1963.

Pressures, Temperatures, Amplitudes - October 14, 1963.

Frequencies - October 14, 1963.

Axial Wall Temperatures - October 14, 1963.

13 inch Location Wall Temperatures

26 inch Location Wall Temperatures

39 inch Location Wall Temperatures

Flow Rate - October 14, 1963.

- October 14, 1963.

- October 14, 1963.

- October 14, 1963.

Pressures, Temperatures, Amplitudes - October 16, 1963.

39

40

40

41

42

43

44

45

46

47

48

49

50

51

52

53

viii
22.

23.

24.

25.

26.

27.

28.

29.

30.

31.

32.

33.

34.

35.

36.

37.

38.

39.

40.

41.

42.

43.

44.

45.

Frequencies - October 16, 1963.

Axial Wall Temperatures - October 16, 1963.

Flow Rate - October 16, 1963.

Pressures, Temperatures, Amplitudes - October 18, 1963.

Frequencies - October 18, 1963.

Axial Wall Temperatures - October 18, 1963.

13 inch Location Wall Temperatures - October 18, 1963.

26 inch Location Wall Temperatures - October 18, 1963.

39 inch Location Wall Temperatures - October 18, 1963.

Pressures, Temperatures, Amplitudes - October 22, 1963.

Frequencies - October 22, 1963.

Axial Wall Temperatures - October 22, 1963.

Pressures, Temperatures, Amplitudes - October 23, 1963.

Frequencies - October 23, 1963.

Axial Wall Temperatures - October 23, 1963.

Flow Rate - October 23, 1963.

Pressure Trace of Oscillation Probably from Plug Flow.

Pressures, Temperatures, Amplitudes - October 24, 1963.

Frequencies - October 24, 1963.

Axial Wall Temperatures - October 24, 1963.

Pressures, Temperatures, Amplitudes - October 30, 1963.

Frequencies - October 30, 1963.

Pressures, Temperatures, Amplitudes - November 6, 1963.

Frequencies - November 6, 1963.

Page

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

ix
Page

46. Pressures, Temperatures, Amplitudes - November 7, 1963. 78

47. Frequencies - November 7, 1963. 79

48. Pressures, Temperatures, Amplitudes - November 8, ‘1963. 80

49. Frequencies - November 8, 1963. 81

50. Pressures, Temperatures, Amplitudes - November 13, 1963. 82

51. Frequencies - November 13, 1963. 83

x
NOMENCLATURE

A

2

= cross sectional flow area, in

c = velocity of sound, in/see

g = gravitational constant, 386 in/sec2

L = length, in

AL = increment of length used in calculations, in

m = mass of fluid in neck of resonator, slugs/12

P = pressure, psia

3

‘G = volume of gas in resonator cavity, in

1

‘G

= volume of gas in outlet plenum and flow channels, in3

Y = ratio of specific heats

P = weight density of hydrogen, lbs/in3

‘H

= frequency of Helmholtz resonator, cps

xi

= fundamental frequency of open-open pipe resonance, cps

‘P
CHAPTER ONE

INTRODUCTION

1.1 PURPOSE

Although heat

capable of inducing

transfer has been known for over 100 years to be

acoustic phenomena, the subject of this investigation was chosen as a result of some relatively recent incidental observations made in what were basically heat transfer experiments. This

investigation is concerned with making a study of pressure oscillations

accompanying heat transfer to hydrogen, and it is being undertaken in

two parts. The one reported here was a preliminary series of experiments designed to probe the fundamental modes of these oscillations,

obtain estimates of their amplitudes, and probe the conditions required

for their occurrence. The final experiments will be designed to collect

data for a more thorough analysis of the phenomena.

1.2 DEFINITIONS

In this report supercritical will mean above the critical pressure

but in the vicinity of the critical temperature. The critical point of

parahydrogen is 187.7 psia and 59.4° R.

1
Superheated will mean at a temperature above the saturated vapor

temperature at subcritical pressures, or above the temperature at which

specific heat is maximized at supercritical pressures.

A dense —— state will mean that which has a temperature below the

saturated liquid temperature at subcritical pressures, or below the

temperature at which

sures.

Pipe resonance

specific heat is maximized at supercritical preswill mean the resonance associated with the fundamental wave length

is comparable with

nodes occur at the

for an open-open pipe. The fundamental wave length

the longest dimension of the pipe, and pressure

open ends. For a pipe of length L at uniform temperature, the frequency of the fundamental tone is given by

c

‘P=~

Helmholtz— resonance is that associated with a

of a cavity connected to an external atmosphere via

The gas in the cavity is compressed and expanded by

motion of the fluid in the neck (or vicinity of the

(1.1)

resonator composed

an orifice or neck.

the to and fro

orifice), analogous

to a spring-mass system. Applying the spring-mass analogy, the frequency of a Helmholtz resonator consisting of a neck attached to a

cavity is derived to be

I

(1.2)

2
1.3 PREVIOUS EXPERIMENTS

In studies of forced convection heat transfer to gaseous hydrogen

and helium, McCarthy and Wolf [1]* observed that under some conditions

heat transfer appeared to become independent of Reynolds number while

being accompanied by pressure oscillations. The frequencies were on

the order of 500 cps, approximately the fundamental acoustic frequency

of the test section between two mixing chambers.

Hines and l?olf [2] reported that in heat transfer experiments with

supercritical hydrocarbons, severe pressure oscillations, with amplitudes up to 380 psi and frequencies up to 10,000 cps, destroyed their

thin walled test sections. They observed these oscillations when the

temperature at which specific heat was maximized was crossed in their

test sections.

Goldmann [3> 4] has observed the production of acoustic noise, which

he described as “heat transfer with a whistle” in forced convection heat

transfer to two-phase and supercritical water. He has attributed this

phenomenon to large property variations under nonequilibrium conditions.

*Numbers in brackets refer to similarly numbered references in bibliography.
Geery [5] and Hendricks [60 have also observed the existence of pressure

oscillations in heat transfer experiments with hydrogen.

Two series of transient cooldown experiments had previously been

performed on heat transfer to liquid hydrogen at Los Alamos. In one

series [7], the forcing of two phase hydrogen through an aluminum

block containing 18 flow channels in parallel produced pressure oscillations which were simulated in frequency by the concept of a Helmholtz

resonator. In the second series [8], supercritical and two phase hydrogen were forced through a single thick walled brass tube with no comparable frequencies of pressure oscillations. The single brass tube experiments raised the following questions about the oscillations observed in

the first series: (i) Were they the result of heat transfer or caused

by feedback loops in the control system? (ii) If they weren’t the result

of feedback loops, why should they appear in one apparatus and not in

the other? (iii) Was parallel channel flow a necessary condition?

(iv) Would the spring-mass concept of a gas and liquid apply at supercritical pressures?

1.4 OBJECTIVES OF PRELIMINARY EXPERIMENTS

A proper apparatus for studying pressure oscillations induced by

heat transfer should contain a steady heat source and allow one to choose

and maintain operating conditions over a period of time. However, because of the delay introduced by the purchase of a suitable dc generator

to electrically heat a test section, it was decided that a number of

fundamental questions could be answered by a more quickly prepared

4
transient cooldown apparatus, discussed in the next section. All

control loops would be open for most of the run to eliminate oscillations caused by feedbacks in the control system. The objectives of

the preliminary experiment therefore became:

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Investigate the existence of resonant modes of pressure

oscillations in forced convective heat transfer.

Identify the Helmholtz resonance mode by a shift in frequency

produced by a chsnge in volume of the resonating chamber and

by a comparison of observed and computed frequencies.

Identify the pipe resonance mode by its restriction to flow

channels between inlet and outlet plena and by a comparison of

observed and computed frequencies.

Investigate the existence of these modes at supercritical

pressures.

Establish the necessity for parallel channel flow by performing experiments with all channels but one plugged.

Obtain approximate notions of where threshold conditions for

these oscillations may lie.

Test the adequacy of instrumentation techniques for such an

investigation at cryogenic temperatures.

5
CHAPTER TWO

APPARATUS

2.1 OVEIUILL SYSTEM

The system employed in this investigation is outlined in Figure 1.

It basically consists of a 300 litre dewar with a 300 psi maximum working pressure, a Fisher-Porter turbine flow meter, a servo control valve,

the test section, and exhaust lines.

Typical operating procedures with a frangible diaphragm separating

the test section from the upstream elements of the system included:

(a) Purging the dewar and all upstream elements through vent

lines with helium and analyzing a sample of dewar contents

with a gas chromatography.

(b) Evacuating and purging the test section with helium.

(c) Filling the dewar to 40% of capacity with liquid hydrogen.

(d) Chilling vacuum jacketed lines up to the frangible diaphragm

to liquid hydrogen temperatures.

(e) Pressurization of dewar with helium until the frangible

diaphragm breaks.

6
(f)

(g)

(h)

(i)

(j)

Setting the pressure for a run and shutting off the helium

supply for dewar pressurization.

Cooldown of the test section with the control valve operating

open loop.

Emptying the dewar of liquid hydrogen.

Purging the system with helium.

Allowing the system to warm for at least 24 hours before the

next run.

2.2 TEST SECTION

The test section was constructed of duraluminum. It is shown in

Figure 2. After rupture of the frangible diaphragm, hydrogen entered

the inlet plenum, where part of it could be bled away for quick chilling of the inlet plenum during the initial phases of a run. A section

of the vacuum jacket was in contact with the inlet plenum walls, acting

like a fin for a heat leak into the plenum.

The central test section piece was a 2-3/4” rod of duraluminum,

52” long, with four holes of 3/16” diameter drilled through on a 1-1/2”

circle. During the last four runs, three of the four flow channels were

blocked by means of a stainless steel wire on which were mounted a nut,

steel washer, and teflon washer on the inlet end. These were pulled

tight against a steel washer and nut in the outlet plenum.

The outlet plenum could be either of two sizes depending on whether

or not a volume filling plug was used. Flow discharged from the outlet
via an orifice plate, which usually operated under sonic flow conditions

limiting flow rates through the system.

2.3 INSTRUMENTATION

Hydrogen temperatures were measured in both plena by Rosemount

platinum resistance sensors. Static pressures were measured in both

plena and in one flow channel 36” from the inlet plenum by Statham

“temperature compensated” pressure transducers attached directly to

the test section. The differential preasure between inlet and outlet

plena was measured directly by a Statham differential pressure transducer. Temperatures in the duraluminum structure were measured by

copper-constantan thermocouples located about 1/16” from the flow

channels. At distances of 13, 26, and 39 inches from the inlet plenum,

a thermocouple was placed, on each of the flow channels, at 45° from

a line passing through the centers of the rod and a flow channel. At

27”, a thermocouple was placed at 135° on one flow passage to check the

strength of angular temperature variation about a flow passage. At

4“, a thermocouple was placed near the same flow channel to check against

unusual axial temperature variations near the inlet plenum.

The outputs of the Statham static pressure transducer were recorded

on a Honeywell Visicorder via amplifiers whose responses were flat to

240 CPS. The output of the differential pressure transducer and the

Rosemount temperature sensora were also displayed on the Visicorder but

through amplifiers whose responses were flat to 24 cps.
The thermocouples’ outputs were sampled 20 times per second by a

Texas Instrument multiplexer and recorded on magnetic tape. These

data were subsequently reduced and plotted by a digital computer.

Flow rate was measured by a Fischer-Porter turbine flow meter and

recorded on a Brown strip chart.

2.4 EXPERIMENTAL DIFFICULTIES

Since one of the objectives of the preliminary experiments was to

test the adequacy of instrumentation techniques for this type of investigation at cryogenic temperatures, a section under the above subtitle

is appropriate.

The first trouble encountered was not in the instrumentation but

is still worth mentioning as a practical cryogenic problem. All o-rings

with a diameter greater than two inches had to be of teflon coated

stainless steel. Neoprene and teflon o-rings leaked at cryogenic temperatures. When using liquid nitrogen, the same o-ring could hold well

after its joint was taken apart and put together several times. However the same type of o-rings could withstand only the initial compression without leaking when exposed to liquid hydrogen.

The turbine flow meter was intended to be the sole means of measuring mass flow rate. Unfortunately the control valve was too big for

the proper flow meter for this experiment. After destroying a flow

meter of an appropriate capacity by overspeeding during purging procedures after the third hydrogen experiment, a unit with a capacity too

large for this investigation was installed. It was of little value

9
during the runs, but aided purging and cooldown procedures. Useful flow

recordings were only obtained for four runs. Flow rates during the runs

were also estimated from sonic flow orifice calculations using outlet

plenum data.

Two difficulties were experienced with recording the output of

thermocouples measuring wall temperatures. First, all thermocouple

pairs were calibrated prior to the runs; but after installation and

recording their output on the Texas Instrument Multiplexer, they consistently recorded temperatures of 470° R when the apparatus was sitting

at ambient temperatures outdoors in pleasant fall weather. This was

observed not only 24 hours after a run, but also when the apparatus

had not been used for f?.vedays. Thermocouple output looked proper

whe~ liquid hydrogen temperatures were achieved, at the end of a run.

Since the Multiplexer did not give rise to such problems in its

previous usage, it is assumed that the technique employed in the installations of the thermocouples stressed them and changed their calibration.

An arbitrary linear correction of 0° R at 60° R and + 70° R at an output

of 470° R was used when analyzing wall temperatures. Wall temperature

graphs presented in thisoreport are uncorrected. It is recommended

that at least one thermocouple be calibrated before and after its placement in a sample installation to avoid an installation technique which

significantly stresses the thermocouple.

The second difficulty in measuring wall temperatures occurred during the last five runs, including all four runs with only one flow

10
passage. The base voltage on the Multiplexer shifted to too high a

value to permit machine reduction of the data. Temperatures for these

runs were recorded only as normalized voltage outputs from the thermocouples.

The Statham pressure transducers were close mounted on the test

section to avoid pressure transmission line response problems. However, their output was temperature dependent even though the units were

“temperature compensated”. Zero shifts with temperature were observed

for the transducers on the flow channel and outlet plenum, but not on

the inlet plenum transducer. Recent analytical studies show this problem can be compromised by using a 6 inch long, 0.005 inch I.D. (1/8”

O.D.) stainless steel transmission tube. At 250 cps, with hydrogen as

the transmitting fluid, the output amplitude was computed to be about

10% high and the phase lag less than a degree. After having its inlet

end exposed to liquid hydrogen for 10 minutes, the transmission tube’s

outlet end temperature was computed to only drop 50° R.

Had good data been the required end product of the experiments,

these runs would have had to be repeated with the troubles eliminated.

However, these experiments were only a preliminary probing to establish

the existence of the phenomena under investigation, and that goal was

achieved as explained in the following sections.

11
CHAPTER THREE

RESULTS

3.1 RESULTS FROM NITROGEN

Since the test sections were proof tested with liquid nitrogen some

data were recorded using that fluid and they are presented here even ti,ough

this report is basically concerned with hydrogen. Figure 3 presents an

observation of pipe resonance during a nitrogen run, as traced from the

Visicorder record. In all the figures made from tracings

corder record, pressure is increasing toward the bottom of

Characteristic of pipe resonance, the oscillations appear

of the Visithe graph.

mainly in the

flow channel and only at considerably diminished amplitudes in the plena.

The flow channel mode also shows a structure indicating the presence of

higher harmonics.

Figure 4 illustrates Helmholtz resonance, characterized by equal

amplitudes in the flow channel and plena and by a frequency dependence

on the volume of the outlet plenum. Comparison of the two runs with

similar fluid conditions but different outlet plena show

differing by a factor of 1.78, which is within 4% of the

frequencies

factor of 1.85

12
predicted by equation (1.2). Even this small discrepancy can be accounted for if one considers that the compressibility of gas in the flow

channels contributes an additional spring effect.

As shown by Figures 3 and 4, pipe and Helmholtz resonant modes

appear independently of one another, but as will be shown later with

hydrogen data and was also observed with nitrogen they may appear superimposed on one another. At the low flow rates accompanying the use of

a 0.07 inch diameter orifice, no pipe resonance was observed in either

nitrogen or hydrogen. This is believed to indicate that higher flow

rates are required to excite this high frequency resonant mode.

3.2 OBSERVED OSCILLATIONS IN HYDROGEN

Figure 5 presents data showing a superposition of pipe and Helmholtz resonances during an experiment with hydrogen. Both modes retained

the characteristics observed in the nitrogen experiments. The Helmholtz mode also appeared on the Rosemont temperature sensor in the

outlet plenum. The almost 180° phase shift is what one would anticipate from a pulsating flow with heat transfer independent of Reynolds

number, as McCarthy and Wolf observed [13. In such a case a pressure

maximum is associated with a flow maximum and consequently an outlet

temperature minimum. This particular section of the record was chosen

because it also illustrates the Helmholtz mode ceasing suddenly while

the pipe mode continued, which is an additional indication that the

two modes are separately excited.

13
Figure 6 shows sawtooth fluctuations and negative pulses typically

observed in the early phases of an experiment. In the experiments performed at supercritical pressures, the negative pressure pulse phenomena was observed to accompany a rise and fall in inlet plenum temperature, as shown on Figure 7. The frequency of these pulses was

not as highly regular as the Helmholtz and pipe resonant modes, but on

the average the period between pulses lengthened as the system cooled

down. Eventually the pulses degenerated into beats when the temperature rise lessened, as shown in Figure 8, and then disappeared.

The accompaniment of the negative pressure pulses by rises in inlet plenum temperature and their amplitude dependence on the magnitude

of the inlet temperature rise indicate this phenomenon is caused by a

heat flux into the inlet plenum. One may visualize a build up of vapor

bubbles at subcritical pressures, or the lower density species at supercritical pressures, until the bubbles are dragged into the flow stream,

cooled by the abundant subcooled hydrogen there, and collapsed, producing a sudden decrease in pressure.

An interesting observation of the negative pressure pulse and

beat phenomenon at supercritical pressures is the disappearance of the

higher frequency modes with a rise in fluid temperature in the inlet

plenum. A plot distinguishing oscillatory and nonoscillatory phenomena

for pipe, Helmholtz, and supercritical modes on coordinates of inlet

fluid pressure versus inlet fluid temperature is shown in Figure 9.

14
A distinct segregation of oscillatory and nonoscillatory conditions

takes place along the saturated vapor pressure-temperature line at

subcritical pressures and the locus of specific heat maxima at supercritical pressures. The latter curve appears to have the interesting

property of being continuous in magnitude and slope with the vapor

pressure line at the critical point.

One can conclude from Figure 9 that pressure oscillations were not

generated in the preliminary apparatua when the inlet fluid was superheated, whether at sub- or super-critical pressures. Furthermore,

since the oscillations did not take place when the entire tube was

filled with superheated hydrogen one may deduce that the mechanism

for driving them occurred only in that part of the flow channel where

the dense state was present.

3.3 COOLDOWN HISTORIES

The following material will present a brief discussion of the

experimental runs in chronological order. The general pattern of

presentation of graphs for each run is:

(1) inlet plenum pressure, outlet plenum fluid temperature, and

average pressure drop between plena versus time; at the top

of this graph, the peak-peak amplitude of the pressure oscillations is also plotted versus time.

(2) Frequency of pressure oscillations versus time.

(3) Temperatures of duraluminum, in the vicinity of the flow

passages at axial locations of 4, 13, 26, and 39 inches from

the inlet plenum face.

15
(4) Duraluminum temperatures close to the four flow channels at

the 13 inch location.

(5) Duraluminum temperatures close to the four flow channels at

the 26 inch location.

(6) Duraluminum temperatures close to the four flow channels at

the 39 inch location.

(7) Volumetric flow rate, in gpm versus time.

Items 4, 5, and 6 were included for only two runs. item 3 appears

on all runs up to October 30, 1963. The remainder of the runs experienced electronic difficulty in the reduction of the wall temperature

data, and consequently the remaining wall temperatures exist only in

a digitized coded form. Item 7 was obtained for only four runs.

October 11

This experiment was performed

pressure of 150 psiA. As shown in

and pressure drop decreased during

at a nearly constant subcritical

Figure 10, the outlet temperature

the recorded portion of the experiment. Three kinds of pressure variations are apparent. The sawtooth

fluctuation, which eventually became negative pulses, persisted in

the first two runs due to a loss of inlet plenum vacuum, which was

later corrected by keeping the neoprene o-rings in vacuum jacket warm.

The Helmholtz and open-open pipe resonant modes also appear. As shown

by Figure 13, the sawtooth and pulse phenomena produced almost full

scale fluctuations in recorded flow. These did not accompany Helmholtz and pipe resonance.

16
The computed outlet temperature and pressure drop obtained using

methods discussed in LAMS 2803 [7] are also shown on Figure 10. The

numerical simulation, which assumed the fluid at the inlet to the test

section to be a saturated liquid, allowed the estimation of a density

and sonic velocity distribution in the test section. The sonic velocity

distribution was used to calculate an open-open pipe resonance frequency

from

1

w

= ——

P 2+

(3.1)

The calculated results appear as triangles on Figure 11.

In computing frequencies for Helmholtz resonance, the mass of all

the hydrogen in the flow channel was estimated by integrating the computed density distribution, and the volume of gaseous hydrogen in the

flow channel was added to that in the outlet plenum for compressibility

considerations. The formula employed for this calculation was

4“1 v PA

‘H = 2TT T

(xPAL) VG (3.2)

These results appear as circles on Figure 11.

The agreement between the observed and computed frequencies provided the second means of identifying the resonant modes. (The first

was by their characteristics, discussed in 3.1 and 3.2.)

A tracing of duraluminum wall temperatures reduced from multiplexer

records is shown in Figure 12. The lines shown are an average through

scatter, which is very narrow at high temperatures but fairly broad in

the cryogenic region.

17
October 14

Results of this run appear in Figures 14 through 20. The planned

difference between this run and the previous one waa the use of a

smaller outlet plenum , which was expected to produce an increase in

Helmholtz frequency, as was observed in nitrogen. The inlet plenum

bleed was left open in the early part of the run to chill the inlet

plenum quickly. This also had the effect of changing the development

of wall temperatures from the preceding run, which in turn probably

affected the density distribution. In essence the average density was

increased. This is evidenced by lower pipe resonance frequencies in

the second experiment for equivalent inlet pressures and outlet temperatures. Consequently, the Helmholtz frequencies are lower than

those which may have been obtained had the density distributions been

similar.

The wall temperatures along the length of the test section, as

shown in Figure 16, exhibit an undulation in their fall which may

either be real or a quirk of the multiplexing system. An argument

that they may have been real is that at a given axial location all the

temperature showed the same undulation. This can be seen by comparing

Figures 17, 18, and 19 which present traces of multiplexer data at

the 13, 26, and 39 inch locations. Towards the outlet of the test

section, at the 39 inch location, there ia little undulation, and it

was not discerned in the outlet plenum temperature recording. Figures

17, 18, and 19 also indicate there waa no thermal asymmetry during the

18
run. Consequently, it is suspected that flow asymmetry among the

channels was also absent.

The sudden cessation of the Helmholtz mode from a 10 psi oscillation at time 312.2 seconds is the event appearing on Figure 5. This

seems to indicate that thresholds exist for oscillations induced by

forced convection heat transfer.

October 16

Much of this run was performed at supercritical pressures, and

results appear on Figures 21, 22, 23, and 24. As shown in Figure 21,

pipe resonance, and for the first time, Helmholtz resonance are demonstrated to exist in hydrogen at supercritical pressures.

There are several other interesting aspects to this run. One is

the rise in amplitude from 6 psi to 9 psi at 305 seconds, when the

pressure dropped from 219 to 181 psia. The pressure excursion at 303

seconds was too rapid and large to provide interpretable data.

Another interesting observation is the abrupt cessation of a

3 psi amplitude Helmholtz oscillation at 315.5 seconds, while the

inlet pressure is 161 psiA and rising. There is no Helmholtz mode

while the apparatus is at a supercritical pressure and the exit temperature at its minimum, but the nwde returns just as the critical

pressure is passed while pressure is falling at the end of the run.

During most of the run, pressure drop fell as the system cooled

down. After 313 seconds with the outlet temperature at about 55° R, the

inlet pressure was increased accompanied by an increase in pressure

19
drop. After 318 seconds, when the pressure was falling again from a

supercritical value, the pressure drop continued to rise until at

325 seconds it was six times greater than it had been at 312 seconds.

The inlet pressure, flow, and outlet temperature were then about the

same as they had been at 312 seconds. This phenomenon may possibly be

attributed to a decrease in the average quality of the test section’s

hydrogen which, in accordance with calculations using a LockhartMartinelli model applied to hydrogen by Rogers [9], would cause

pressure drop to increase to a maximum with decreasing quality. However the quality dependence of the calculated frictional pressure gradient is small at this pressure, and it may not account for the entire

increase in pressure loss.

Another possible cause of the increased pressure drop may be a

transition from film to nucleate boiling over an increasingly longer

length of the flow channels. This is suggested because the existence

of a stable vapor layer on a solid surface in film boiling has been

demonstrated to provide a large reduction in friction drag [10]. Wall

temperature records, shown in Figure 23, lend credence to this hypothesis because they show only the 4“ temperature bottomed out at 312

seconds, but all wall temperatures bottomed out at 325 seconds.

October 18

The intent of this run was to study pressure observations at very

low flow rates of the order of 0.2 gpm. Results are shown in Figures

/

20
25, 26, 27, 28, 29, and 30. Since pipe resonance was absent during

this run it seems that flow rates higher than those encountered are

required to excite it. The pressure drop was almost zero during the

entire run.

Helmholtz resonance appeared in the latter part of the run and

exhibited a sudden cessation at 240 psfA at 760 seconds and made a

second appearance later as the pressure waa falling towards 200 psiA.

An oscillation, appearing only at supercritical pressures, is

shown in Figure 25. As closely as the recordings could be read, this

mode started when pressure ascended to the critical value, existed at

pressures above it, and stopped when pressure decended to the critical

value. As seen in Figure 26, in contraat to the Helmholtz mode, the

supercritical frequency remained almost constant during the cooldown.

As pressure fell below the critical value at 788 seconds, the

outlet temperature began to rise even though the test section was

cooling. From this, one can infer that the intensity of turbulence

was greater with two phase flow than with supercritical flow. If

that is correct, then it might also be possible that the aupercritical

mode may arise from a transition such as that between laminar and

turbulent flow. The low frequency mode shown in Figure 7 is the supercritical oscillation.

Figures 28, 29, and 30 again demonstrate that no thermal asymmetry

occurred during the course of the experiment.

21
October 22

In this run, pressure was varied several times between values

around 240 psiA and the critical pressure. The results appear in

Figures 31, 32, and 33. The differential pressure is not given as the

/

associated electronic circuitry failed during the ccurse of the run.

Pulses, pipe resonance, Helmholtz resonance, and the supercritical

mode appeared during this run. Figure 31 shows the only apparent

existence of what is called the supercritical mode below the critical

pressure. I.%ether this actually occurred or is the result of a drift

in the transducer’s calibration will be investigated in future experiments.

October 23

This run

comparatively

was made to observe pressure oscillations occurring at

high flow rates. The results are shown in Figures 34,

35, 36, 37, and 38.

The flow record, Figure 37, shows none of the large oscillations

that accompanied sawtooth and pulse fluctuations at lower flow rates.

Pipe

resonance

after the

resonance persisted throughout most of the run, but Helmholtz

made only a brief appearance. At 262 seconds, 3 seconds

outlet temperature bottomed out, a new type of oscillation

appeared with an amplitude in the inlet plenum larger than in the flow

channel. Either subcooled and two phase or all two phase conditions

existed throughout the test section. This new mode herein identified

as plug flow, must be associated with such conditions. Traces from a

22
high speed recording of operative pressure channels are shown in the

upper half of Figure 38. Plug flow is suggested as a source of these

oscillations because a rise in inlet pressure was coincident with a

reduction in pressure drop. The formation of a vapor plug in a channel

would tend to slow flow and thereby produce a reduction in pressure

drop between plena and an increase in inlet pressure due to a relative

back up of fluid. Also, the oscillations in the flow channel are

smooth while those in the inlet plenum are irregular in form, which

very likely could be caused by the non synchronous formation of plugs

in all four channels. A single channel experiment did not show the

irregular pressure wave form at the inlet plenum. The average pressure

drop remained fairly constant during the existence of these oscillations. This differs from phenomena observed at lower flow rates when

a rise in pressure drop was usually observed. Finally, it should be

recalled that in the CISE experiments [11], plug flow followed a dispersed flow pattern when liquid rates were held constant and gas rates

reduced. Since hydrogen has a low surface tension it tends to disperse very easily, and only at high flow rates with the low vapor

generation provided by a cold apparatus would plug flow be anticipated.

Comparison of Figure 36 with 27, a record from a low flow rate

cooldown, shows that there was a much greater axial wall temperature

gradient in a slow cooldown than in a fast one.

23
——October 24

The intent of this run was to reproduce the run of October 18

but with a smaller outlet plenum. Results from the run are shown

in Figures 39, 40, and 41. As on October 18, this run contained no

pipe resonance modes, but unlike the earlier run, the supercritical

mode made only a brief appearance and the amplitude of the Helmholtz

mode was much larger. Pressure drop was nearly zero throughout the

run.

Comparison of the two runs indicates they were not as similar

as had been hoped since the run of October 24 achieved liquid hydrogen

temperatures in the outlet plenum nearly 200 seconds before they were

reached during the run of October 18. Not only flow rates but hydrogen

density distributions were probably different for comparable outlet

temperatures. Nevertheless, the experiment performed with the smaller

outlet plenum did have higher frequencies for comparable outlet temperatures. These were not as high as anticipated because the higher

flow rate in that experiment probably allowed a greater mass of hydrogen

to exist in the flow channel of the small plenum experiment than in

the large plenum experiment.

October 30

In this experiment, inlet pressure was brought up to ahnost 280

psiA, dropped to 170 psiA, and again raised into the supercritical

region. Results are shown in Figures 42 and 43. The differential

pressure circuitry failed during the course of this run but was

24
restored in time to observe a post chill down pressure drop rise at

supercritical pressures. This had been observed and anticipated at

subcritical pressures, but here was the same phenomenon at supercritical

pressures.

Helmholtz and pipe resonance modes were present during this run.

November 6, 7, 8, and 13

These runs are considered in a

objective of checking the necessity

ment for the observed oscillations.

group because they had the common

of parallel channel flow as a requireThree of the four flow channels

were plugged, or at least given an extremely high impedance compared to

the open channel, by slipping a stainless steel wire with both ends

threaded into the channels; installing a teflon washer, a stainless

steel washer, and a nut on the inlet end; and tightening against this

with a stainless steel washer and a nut in the outlet plenum. Flow

rates were reduced; but the inlet plenum heat leak, which led to the

recognition of the inlet state as a necessary condition for Helmholtz,

pipe resonance, and supercritical oscillations in this apparatus, now

often provided inlet temperatures that

to occur. As a result there were long

no oscillations appeared and others in

were too high for oscillations

periods of these runs in which

which their appearance was

sporadic. Nevertheless, at various times all classes of pressure fluctuations were observed.

The results are shown in Figures 44 through 51. It is interesting

to note at 1080 seconds in Figure 45, the Helmholtz frequency is 4.5 cps.

25

—
Under roughly similar conditions in a four channel experiment, 295

seconds in Figure 11, the Helmholtz frequency is 9 CPS. This dependence

on flow area is in accord with equation (3.2).

As in the four channel experiments, Figure 50 shows an increasing

pressure drop as outlet temperature bottoms out. It also displays plug

flow oscillations, with the inlet plenum amplitudes larger than those in

the flow channel. However, unlike the four channel experiment, the inlet

plenum oscillations are not irregular in form, as seen in the lower half

of Figure 38.

Examination of data from these single channel experiments indicates

that all categories of pressure oscillations observed in the four channel

experiments should be seen in the single electrically heated tube of the

final apparatus.

26
CHAIPTER FOUR

CONCLUSIONS

The conclusions of this investigation can be classified according

to three categories: (1) pressure oscillations, (2) cooldown phenomena,

and (3) instrumentation.

4.1 PRESSURE OSCILLATIONS

A. Five classes of pressure fluctuations have been recognized in

these experiments:

a. Open-open pipe resonance occurs in a resonant system confined to a flow channel, but this mode radiates into plena

and its pressure oscillations have been observed there at

diminished amplitudes. This mode was identified by this

characteristic and by a comparison of observed with computed frequencies. The calculation of these frequencies

required a knowledge of the sonic velocity distribution in

the flow channel. This mode was observed at sub and

supercritical pressures.

27
b. Helmholtz resonance, the acoustic analogy of a springmass system, exhibited equal amplitudes in flow channels

and plena. Besides this characteristic, it was alao identified by a predictable dependence on outlet plenum volume,

flow channel area, and by a comparison of observed with

computed frequencies. The frequency computation requires

the flow channel density distribution to be known. This

mode was observed at sub and supercritical pressures.

c. The supercritical mode is so named because it was observed

to start when ascending pressure reached the critical value

and to stop when a descending pressure again reached that

value. The amplitude of this mode was observed to be

equal in the flow channel and plena; and its frequency in

many runs seemed almost independent of the cooldown, typically remaining near 9 cps. A possible cause of this mode

may be an instability caused by a flow transition such as

that between laminar and turbulent flow.

d. PM flow oscillations were observed only at subcritical

pressures, high flow rates, and in an apparatus cold enough

to produce a liquid hydrogen temperature in the outlet

fluid.

lations

farther

between

Other identifying characteristics of these oscilwere a larger amplitude at the inlet plenum than

downstream in the flow channel, a phase reversal

inlet plenum pressure oscillations and pressure

28
difference between plena, and a smooth inlet plenum

oscillation for single channel flow, while four channel

flow produces an irregular pressure wave form in the inlet plenum.

e. Sawtooth @ negative pulse fluctuations were attributed

to a heat flux from elements upstream of the flow channels,

specifically the inlet plenum. Sawtooth fluctuations were

usually followed by negative pressure pulses, and the

latter degenerated into beats. These fluctuations were

accompanied by large scale variations in flow rate.

These fluctuations were observed at sub and supercritical

pressures. However, at supercritical pressures the magnitude of the flow oscillations were reduced; and in a high

flow rate experiment, these fluctuations were not present.

B. Helmholtz, pipe, and supercritical resonant modes were not

observed in the test section when the inlet fluid was superheated. From this, one can deduce that the mechanism for driving these modes occurred in only that part of the test section

in which a dense atate was present.

c. Flow in multiple parallel channels was shown not to be a

necessary condition for these pressure oscillations.

D. The pressure oscillations were not caused by feedback loops in

the control system, because they occurred when these loops were

not operating.

29
E. The amplitude of the Helmholtz mode generally tended to be

higher at lower flow rates. As cooldown progressed and

frequency decreased, this amplitude would typically increase

to a maximum and then decrease to zero. Sometimes this mode

would suddenly cease to exist when the amplitude had previously been increasing.

F. The existence of wall temperature thresholds for pressure

oscillations at low temperatures might be inferred from the

observed sudden cessations of Helmholtz resonance. The threshold picture at higher temperatures is clouded by the production

of superheated inlet hydrogen early in the run. The low flow

runs with a 0.07 inch diameter orifice may be interpreted as

indicating the existence of a low flow threshold for pipe

resonance. They also may be interpreted as indicating that a

lower flow threshold exists for the lower frequency Helmholtz

mode than for pipe resonance.

G. Since Helmholtz and pipe resonance frequencies were observed

to vary continuously during an experiment, the excitation of

these modes probably occurs over a spectrum of frequencies.

4.2 COOLDOWN PHENOMENA

A. When cooling of the test section produced no further drop in

hydrogen temperature at the outlet plenum, an increase in

pressure drop was often observed. This occurred at sub and

supercritical pressures but not at very high flow rates when a

30
B.

c.

D.

plug flow pattern was believed to exist. This phenomenon

may be caused by a transition from film boiling to nucleate

boiling over an increasingly longer length of flow channel,

or it may be caused by an increasing internal shear stress

as the average hydrogen quality is decreasing. The latter

concept tends to agree with two phase flow calculations by a

Lockhart-Martinelli method applied at the pressures of these

experiments. However the calculated dependence of frictional

effects on quality appears to be too small to account for the

entire increase in pressure loss. Similar processes might have

taken place at supercritical pressures between high and low

density regions of hydrogen.

Greater axial temperature gradients were observed

cooldowns than in the fast ones.

When the test section pressure was lowered across

in the slow

the critical

value at low flow rates, a noticeable change occurred in the

time derivative of the outlet temperature. The change always

indicated an improvement in heat transfer at subcritical

pressures. At some times a rise in outlet temperature was

observed as the system cooled down when pressure went from

super to subcritical. One interpretation of this phenomenon

is that there is a higher intensity of turbulence in two phase

flow than in supercritical flow.

The test section showed no indication of thermal asymmetry

either between flow passages or around a flow passage.

31
E. The inlet end of this test section did not show the unusual

elevation of wall temperature observed in the apparatus of

Watts, et al., [8]0

4.3 INSTRUMENTATION

A. Lengths of pressure transducer transmission lines should be

carefully selected to meet the conflicting requirements of a

good frequency response and a minimum variation in transducer

temperature.

B. Before a method of installing thermocouples is chosen, some

thermocouples should be calibrated before and after a sample

installation to assure that the installation technique does

not affect their calibration.

32
BIBLIOGRAPHY

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

McCarthy, J. R., and Wolf, H., “The Heat Transfer Characteristics

of Gaseous Hydrogen and Helium,” Rocketdyne Research Report

RR-60-12 (December 1960).

Hines, W. S., and Wolf, H., “Pressure Oscillation Associated with

Heat Transfer to Hydrocarbon Fluids at Supercritical Pressures and

Temperatures,” A.R.S. Jour., 32, 3, 361-366 (March, 1962).

Goldmann, K., “Boiling Songs,” NDA 10-68 (My 1953).

Goldmann, K., “Heat Transfer to Supercritical Water at 5000 psi,

Flowing at High Mass Rates Through Round Tubes,” —-Int. Devl .in

Heat Transfer, ASME, 561-568 (1961).

Geery, E. L., Private Communication (April 1963).

Hendricks, R. C., Private Communication (April 1963).

Thurston, R. S., “Effect of Two-Phase Flow in Startup Studies of

Kiwi-B,” Conf., LAMS-2803 (October 1962).

Watts, G. P., Lyle, A. R., and Balcomb, J. D., “Cryogenic Cooldown

Experiments ,“ Proceedings of Nuclear Propulsion Conference, TID7653 (Pt. 2), Conf., (1962~

Rogers, J. D., “Two Phase p-~ Friction Factors,” Adv. &n Cryogenic

Eng., ~, K. D. Timmerhaus (cd.), Plenum Press, New=rk (1964).

Bradfield, W. S., Barkdoll, R. O., and Byrne, J. T., “Some Effects

of Boiling on Hydrodynamic Drag,” ——Int. J. —.Heat and —Mass Transfer,

& 615-622, (1962).

“A Research Program in Two Phase Flow,” CISE (Centro Informazioni

Studi Esperienze) , Milan, Italy, M. Silvestri, Dir., (January 1963).

33
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NITROGEN

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EXPERIMENT OF SEPTEWWZR 30, 1963

8.15 in3 outlet plenum

0.203 h orifice

Figure 3. Pipe Resonance in Nitrogen

36
NITROGEN

multiplexer time, SECONDS

L t # 1 1 1 1 I

5Le 521 Sz& SIZ3 6A+ S25 526 SL7

outlet plenum

l!58°Rat Inlet, 200°R at outlet

13r=

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flow channel

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K+19c.- Experiment of October 1, 1963 Inlet plenum

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flow channel

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multiplexer time, SECONDS

Experiment of October 2,

—.27.9 ln3 outlet plenum

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1963

0.07 in orifice

Figure 4. Outlet Plenum Volume Effects on Helmholtz Resonance in Nitrogen

37
HYDROGEN

Experiment of Oatober 14, 1963

multiplexer time, SEcolms

311 312 3

I 1 I k 1 i I 1 t I i I I 1 I k I 1 1 I I L I 1 1 I 1 1 k I I I

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I*O- outlet plenum temperature

ls-onote sudden cessation of Helmholtz oscillation

& phase difference between temperature and pressure

Figure 5. Superposition of pipe and Helmholtz Resonances in Hydrogen

38
HYDROGEN

Experiment of October 14, 1963

multiplexer time, SECONDS

l%IA 233. 233 23* %3s

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Experiment of October 11, 1963

multiplexer time, SECONDS

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20 260 261 z6a

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NEGATIVE PRESSURE PULSES

Figure 6. Sawtooth and Negative Pulse Phenomena in Hydrogen

39
HYDROGEN

Experiment of October 22, 1963

multiplexer time, SECONDS

,............... .........[. 111, ,1, J\l, ,J11s8t111*1~ro1 ii

2@7 Z88 289“ 290 29I 292

60=

inlet plenum temperature

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E a6e- +~ Inlet plenum pressure

Figure 7. Negative Pressure Pulses Accompanying a Rise in Inlet Temperature at Supercritical Pressures

HYDROGEN

Experiment of October 22, 1963

multiplexer time, SECONDS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . ..1.. s.{...9 . ,

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Figure 8. Pressure Beats Accompanying a TWO Degree Rise in Inlet Temperature at SuperCritical Pressures

40
TEMPw’ruR& DEGREES KELVIN

Figure 9. Dependence of Pressure Oscillations on Inlet Conditions

41
---

Multiplexer Time, SECONDS

Figure 10. Pressures, Temperatures, Amplitudes - October 11, 1963

42
MultiplexerTime, SECONDS .

Figure 11. Frequencies - October 11, 1963

43
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Figure 12. Axial Wall Temperatures - October 11, 1963

44
MULTIPLEXER TIME, SECONDS

Figure 13. Flow Rate - October 11, 1963

45
Multiplexer Time, SECONDS

Figure 14. Pressures, Temperatures, Amplitudes - October 14, 1963

46
--

Multiplexer Time, SECONDS

Figure 15. Frequencies - October 14, 1963

47
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48
Figure 17. 13 inch Location Wall Temperatures - October 14, 1963

49

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50
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Figure 19. 39 inch Location Wall Temperatures - October 14, 1963

51
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Figure 20. Flow Rate - October 14, 1963

52
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Multiplexer Time, SECONDS

Figure 21. Pressures, Temperatures, Amplitudes - October 16, 1963

53
MultiplexerTime, SECONDS

Figure 22. Frequencies - October 16, 1963

54
WALL l_ EM PER ATv RE I+ IS-I-ORY

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55
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Figure 24. Flow Rate - October 16, 1963

56
Multiplexer Time, SECONDS

Figure 25. pressures, T’emperatures, Amplitudes - October 18, 1963

57
1

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Figure 26. Frequencies - October 19, 1963
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59
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\

~- 300

Q

~ \

T ~s~ ‘.\

u

\

\

2

\

x ‘\

%

\

+

‘w-’ ‘ \

6

1,,1 I lll!llil 111111111 llllllt lllllJl,,,,l i,, \,l, ~l

300 3.<0 460 qso Sw Sso 600 4s0 708 7s0 ro o

Figure 28. 13 inch Location Wall Temperatures - October 18, 1963

60
3 ?o” APART

50 c1 I 1 1 1’”’’ 1’’’’ 1’’’’ 1’’1’1’1”1 ‘llnl’-ulll~ut]v,

/

1

‘ ‘-i

—.— . ?AX,L 1

f, z

. ------ “ 3 ——

[

“ 4

. ..9..”” 2~’’c-.n tik~

-i ~“’deep

6 Fill I l,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,: I

300 3 so q 60 q so Soa Sso 600 6s0 70o 7S0 ●o e

Fi~~r~ 2$). 26 inch Location Wall Temperatures - October 18, 1963

61
13/3z “ deep r-ad+.

500 ~, , I 1 l“’’I’’’’ 1’’’’ 1’’’’ 1”’” l“’’1”’’’ 1’’’’ 1’’”.

—.— p.aa}b. 1

●

~:z

--

4s0

------

:V

_— It

43

\

<.\

\

\

“%N -.

0 llillli!ll 1111111 lllJllil!tltllll !llltlllll11\ilitj

4 300 3 .s0 400 1s0 S-00 .rSo @o 6s0 700 7s0 roe

Figure 30. 39 inch Location Wall Temperatures - October 18, 1963

62
Fig

Multiplexer Time, SECONDS

,ure 31. Pressures, Temperatures, Amplitudes - October 22, 1963

63
I

MultiplexerTime, SECONDS

Figure 32. Frequencies - October 22, 1963

64
WALL T~FAPEI%ATcJ (lE J-IIS TCYRY

/$T

FOUR 14XlA~ LOCATIONS.

500

1 I I 1 1 I I I I I I I 1 I I I I I I I I 1 I I -1

4s-0

400 —

350

300

2so

200

13-0

/00I

\

\

L

\\,\

\.\

‘.

. \ . \

50 F- 4

0

I I I I I I I I I 1 I I I 1 I I / I I 1 I 1 ,,~

~oo 220 avo Xfio 280 300 320 3v0 360 380 //00 420 +Qo

Figure 33. Axial Wall Temperatures - October 22, 1963

65
Fi

Multiplexer Time, SECONDS

.gure 34. Pressures, Temperatures, Amplitudes - October 23, 1963
rn

@l

CJ

MultiplexerTime, SECONDS

Figure 35. Frequencies - October 23, 1963

67
——. 35” $-WI -Ie+ fle.!

.—O—” Z6”qm *

1.

,, ,, r, ,,

400

3s0

----- ----- _

too

so

o Llll

MVI-Tl ?LEZER TIME , SE CO AIDS

pREsSU~E OS CILL~TIO/V E%- I> ERI/WEIUT

-~

QctOb~r 23 , 196s

ki~-.’~ //7 dt.OJ@a X- /c t co,, d; +;L%3

c9.:fTe e >LIwEf< = .338 ;-I 0. +!e + pfe. .m - 27.9%3

Figure 36. Axial Wall ‘i’emperatures- October 23, 1963

68

,

5-
1

MULTIPLEXERTIME, S.ECO~S --w z94

Figure 37. ~lOW Rate - October 23, 1963

69
HYDROGEN

EXPERIMENT OF OCTOBER 23, 1963

FOUR CHANNEL FLOW

multiplexer time, SECONDS

263.7 X3.8 a63*9 26%0

I i 1

70 y

80 - flow channel

~ 28 CPS

.

25: differential pressure

EXPERIMENT OF NOVEMBER 6, 1963

SINGLE CHANNEL FLOW

mUltip18xf3r time, SECONDS

&so 681 68.L 683 68* 685 686

I 1 I b I

flow channel

Figure 38. Pressure Trace of Oscillation Probably from Plug Flow

70
---

Multiplexer Time, SECONDS

.

?i.gure39. Pressures, Temperatures, Amplitudes - October 24, 1963

71
1

&

$

cl

3

g

Be 0 qee -0

Multiplexer Time, SECO~g

Figure 40. Frequencies - October 24, 1963

72
.\

400 —

3<0

300

Y

o

z So

.

w

e Zf+

:

.

t

I00

~

: ‘JO

CJ

I 1 , ! t , 1 I I 1 1 I 1 1 t [ 1 1 I 1

vi o

260 .2g0 300 320 340 360 390 ? 00 .iLo 4W0 +60 Wtio

qvLl_Ip LEzER TIME, SECOND>

Figure 41. Axial Wall Temperatures - October 24, 1963

73
I

I

--—

MultiplexerTime, SECONDS

Figure 42. Pressures, Temperatures, Amplitudes - October 30, 1963

74
Multiplexer Time, SECONllS

Figure 43. Frequencies - October 30, 1963

75
MultiplexerTime, SECONDS

Figure 44. Pressures, Temperatures, Amplitudes - November 6, 1963

76
Multiplexerl!lme,SECONDS

Figure 45. Frequencies - November 6, 1963

77
MultiplexerTime, SECO~S

Figure 46. Pressures, Temperatures, Amplitudes - November 7, 1963

78
MultiplexerTime, SECONDS

Figure 47. Frequencies - November 7, 1963

79

—
Figure 48. pressures, Temperatures, Amplitudes - November 8, 1963

80
Figure 49. Frequencies - November 8, 1963
S60

s-a 6

qoo

Zoo

&o o

0

MultiplexerTime,”-SECoNDs-

--

Figure 50. Pressures, Temperatures, Amplitudes - November 13, 1963

82
MultiplexerTime, SECONDS

Figure 51. Frequencies - November 13, 1963

83