jf Standards

NBS NOTE

Slush Hydrogen Pumping

Characteristics

364

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U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

llilili«iiii: wiia: -:'

UNITED STATES DEPARTMENT OF COMMERCE

C.R. Smith, Secretary

NATIONAL BUREAU OF STANDARDS • A. V. Astin, Director

NBS TECHNICAL NOTE 364

ISSUED APRIL 1, 1968

SLUSH HYDROGEN PUMPING CHARACTERISTICS

D. E. DANEY, P. R. LUDTKE, D. B. CHELTON

ANDC. F. SINDT

Cryogenics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means tor making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature.

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402

Price 30 cents.

TABLE OF CONTENTS

Page

ABSTRACT „ . „ . . v

1. Introduction 1

2. Nomenclature - . 2

3. Pump Description 3

4. Liquid-Solid Mixture Characteristics ............ 3

5. Test Facility ...... . 7

6. Instrumentation and Data Acquisition 10

7. Test Procedures 11

7. 1 Performance Tests ll

7.2 Cavitation Tests .................... 12

8. Test Results 13

8. 1 Performance Characteristics ............. 13

8. 2 Cavitation Characteristics .............. 2 1

8. 3 Pump Wear 26

9. Conclusions . 26

10. Acknowledgements . 26

11. References . 27

12. Appendix - Pump Cavitation Curves 28

in
TABLE OF CONTENTS (CONTINUED)

Pag<

List of Figures

Figure 1. Pump Assembled 4

Figure 2. Disassembled Pump 5

Figure 3. Pump Shaft Assembly 6

Figure 4. Pump Installation in Generator . . 8

Figure 5. Pump Flow Schematic 9

Figure 6. Pump Performance Map, Developed Pressure ..... 17

Figure 7. Pump Performance Map, Developed Head 18

Figure 8. Pump Efficiency, 11,000 RPM ............. 20

Figure 9. Pump Cavitation Constant for a 15 Percent Reduction

in Developed Head 22

Figure 10. Pump NPSH/N vs. Q/N for a 15 Percent Reduction

in Developed Head 23

Figure 11. Pump Cavitation Curves - 11, 000 RPM 24

Figure 12. Pump Cavitation Curves - Approximately 14, 000 RPM 25

Figures 13-22. Pump Cavitation Data - 11, 000 RPM. ...... 29-33

Figures 23-29. Pump Cavitation Data - Approximately 14, 000

RPM. 34-37

List of Tables

Table 1. Pump Test Summary. 14

Table 2. Pump Performance Test Data 15-16

IV
ABSTRACT

The pumping characteristics of liquid- solid mixtures of parahydrogen (slush hydrogen) were investigated using a centrifugal type

liquid hydrogen pump with a specific speed range of 1600 to 3100. Performance tests at 8, 000, 11, 000, 14, 000, .and 19, 000 rpm and cavitation tests at 11, 000 and 14, 000 rpm were made. As predicted by

theory, the developed head for liquid and slush hydrogen are the same

when the difference in density is considered. The pump efficiency,

cavitation constant and NPSH requirements for slush hydrogen are

also the same as for the triple-point liquid. After 34 minutes running

time with slush hydrogen out of a total running time of 79 minutes,

the pump components showed no wear over that expected from operation in liquid.

Key Words: Cavitation, centrifugal pump, cryogenic pump, liquidsolid hydrogen mixtures, slush hydrogen.

SLUSH HYDROGEN PUMPING CHARACTERISTICS*

D. E. Daney, P. R. Ludtke, D. B. Chelton

and C. F„ Sindt

1. Introduction

The pumping characteristics of liquid-solid mixtures of parahydrogen (slush hydrogen) are of considerable interest since its use as a rocket propellant would require that it be pumped in ground installations

and space vehicles. Extrapolation of relationships for pumping water

slurries [ Stepanoff, 1963] indicates that the pumping characteristics of

liquid and slush hydrogen should be the same when the difference in

density is considered. This contrast to water slurry behavior is due to

the similar flow losses for liquid and slush hydrogen.

In order to compare experimentally the pumping characteristics

of liquid and slush hydrogen and to investigate possible pump wear or damage due to slush hydrogen, a test program with the following objectives

was established:

1. To determine if slush hydrogen can be pumped with a centrifugal type liquid hydrogen pump,

2. To compare the pump performance with slush and triple -point

liquid hydrogen at 8, 000, 11,000, 14, 000 and 19, 000 rpm,

3. To determine the pump cavitation characteristics of slush and

triple -point liquid hydrogen at 11, 000 and 14, 000 rpm, and

* Sponsored by NASA-Marshall Space Flight Center, Huntsville,
4. To investigate the effects of slush hydrogen on inducers,

impellers, propellant cooled bearings, labyrinth and dynamic face seals,

and other pertinent pump components.

2. Nomenclature

A desired operating speed in rpm (8, 000, 11, 000,

14, 000 or 19, 000)

B ratio of the desired operating speed to the actual speed

e pump efficiency

F mass solid fraction of slush hydrogen

H developed head in feet

n number of data points in a pump performance test

n specific speed, N/Q/H37 4

N pump speed in rpm

NPSH net positive suction head

Q pump capacity in gpm

t time in minutes

V volume of fluid in the generator in gallons

x solid hydrogen particle size in inches

y(x) particle size distribution function

NPSH Thoma's cavitation constant, H

Subscripts

i denotes instantaneous value of a parameter

t denotes liquid

m denotes a liquid- solid mixture
3. Pump Description

The pump used in the tests was a commercially available centrifugal type chilldown pump designed for the Saturn S IV-B. Figures 1, 2,

and 3 show the pump assembled and disassembled. It has been modified

by the addition of a helium gas driven turbine and by the separation of the

discharge volute from the motor housing . The latter modification was

made so that the pump could be inserted into the slush generator through

the 6-inch diameter windows.

The pump has a fully shrouded impeller 2.8 inches in diameter

with six backward swept vanes. The minimum dimension of the impeller

passage is 0. 25 inches. An unshrouded axial flow inducer stage delivers

the fluid to the impeller. Both the turbine and pump bearings are liquid

cooled stainless steel ball bearings with phenolic bearing cages.

Driven by the 400 Hz, 42 volt a-c induction motor, the pump

runs at a nearly constant speed of 11, 000 rpm and has a nominal flow rate

of 135 gpm at 7 psi developed pressure. Driven by the helium turbine,

the pump has a variable speed of 6, 000 to 19, 000 rpm, flow rates to 350

gpm, and developed pressures to 26 psi. The specific speed ranges from

1, 600 to 3, 100.

4. Liquid-Solid Mixture Characteristics

The properties of slush hydrogen have been described in detail

elsewhere [Mann, et al. , 1965, 1966]. Briefly, they are as follows:

Slush hydrogen is a mixture of liquid and solid parahydrogen at, or near the triple-point conditions of 13. 8 K and 52. 8 torr (0. 07 atmosphere). The density of the triple-point liquid is 77.0 g/l; the density

of the solid is 86.6 g/l. During the present tests the mixture was

[l] Modification by NASA-Marshall Space Flight Center.
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pressurized to one atmosphere with helium gas. The solid fraction by

mass ranged from 0. 19 to 0. 55 with an average value of 0. 33.

The freeze-thaw technique was used in preparing the mixture.

The particles produced by this technique are very irregular in shape

>

having a coefficient of drag 5. 6 times that of a sphere. They range in

size from . 02 to 0„ 39 inches and follow a logarithmic distribution

approximated by

,

. r _,, {254x-l} .1

y(x) = exp ^-Z(ln — )j ,

where y(x) is the unnormalized distribution function and x is the particle

size in inches. The most common particle size is . 08 inches.

The flow characteristics of hydrogen slush have been studied in a 5/8-inch I„D. transfer line by Sindt and Ludtke [See Weitzel.et al„ , 1968] . No significant difference was observed between pipe line pressure drop for

triple -point liquid and slush hydrogen in the flow range of interest for the

pump tests.

5. Test Facility

Because of the desirability of using the existing slush hydrogen

facility, the pump was mounted inside the 120- gallon (450-liter) slush

generator as shown in figure 4. The generator has three 6-inch diameter,

equally spaced observation windows through which the pump was inserted.

Each component was separately placed through a window and the components were then reassrmbled inside the dewar. A 2-inch pump discharge tube, and the smaller helium turbine inlet and exhaust lines> provided

support for the pump.

Figure 5 shows the pump flow system. It consists basically of a slush generating dewar containing the pump and the 2-inch discharge
Pumping Line

Slush Hydrogen

Transfer Line

Support CableReturn Line

View Port

If— /N2

Fill

m^ NN2 Vent

Support Rods

Pump Discharge

Line

-Thermal Radiation

Shield

Figure 4. Pump Installation in Generator
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line which passes through the window to a 500 gallon receiving dewar.

Slush may be pumped to the receiver or alternately through the return

loop back into the generator „ The globe valves provided in the transfer

line allow control of the flow and developed pressure of the pump.

The turbine is driven by helium gas precooled with liquid nitrogen.

A square wave inverter requiring a 54 volt d-c input supplied the 400 Hz,

42 volt a-c power for the motor drive.

6. Instrumentation and Data Acquisition

The data, with the exception of the d-c power to the inverter and

the slush density, were recorded at 0. 2 second intervals on magnetic

tape by a data acquisition system.

The pressures were measured with variable reluctance type transducers mounted external to the generator. A. magnetic pickup, located at

the splines in the pump shaft, sensed the pump speed. The fluid volume

was determined at fixed intervals by the 10 carbon resistor liquid level

sensors shown in figure 4. A nuclear radiation attenuation densitometer

described by Weitzel, et al. [ 1968] was used to determine the solid

fraction of the hydrogen slush in the generator.

The precision of the instrumentation, as typified by the standard

deviation of the instrument calibrations, is 0„ 3 feet in H, 0. 1 foot in

NPSH and 2.6% of N. The error in the pump capacity measurements is

estimated to be no greater than 5% while the uncertainty in the pump d-c

power consumption measurements is also estimated to be about 5%„ The

densities measured by the densitometer are estimated to be accurate to

within 0. 5% in density at the heaviest concentrations of solid, and to be

better than this at lower concentrations. The systematic errors in H,

NPSH and N are estimated to be of the same order as the precision.

10
However, since the pump performance with slush and liquid are compared, small systematic errors have no effect on the comparison.

7. Test Procedures

7. 1 Performance Tests

Following the production of slush or triple-point liquid, the

generator was pressurized to approximately one atmosphere with helium

gas. The transfer line valve was opened to give the desired flow rate

and the pump was started. The receiver was vented to the atmosphere

through a one psi check valve, and helium gas was admitted to the

generator to maintain the pressure at one atmosphere. During the electric motor runs, the turbine was purged with helium gas to maintain the

pumped fluid below the turbine blades. In general, the drop in liquid

level spanned several liquid level sensors, corresponding to a volume of

approximately 60 gal. (225 liters). Only a portion of each test was considered for the performance calculations, the first portion of the test

being dominated by transient conditions.

Typical transient conditions are exemplified by an abrupt increase

in pump speed from 10, 000 to 1 1 , 000 rpm, accompanied by a decrease in

d-c current from 2 7 to 21 amps. In the turbine drive tests, the throttle

valve was set at a predetermined opening with little or no adjustment

made during the run. As a result, the measured speed varied in some

cases as much as several hundred rpm during the test. The average

speed between tests varied as much as 1, 000 rpm from the desired speeds

of 8, 000, 14, 000, and 19, 000 rpm.

Because of these variations in the pump speed, the pump affinity

laws were used to obtain average values of developed head and flow at the

desired speed. The affinity laws were applied in the following manner:

11
B. = A/N.

1 1

1 2

H. = H. B.

i li

i=n i 3. H = T, H./n

i=l i

i=n

4. B = E B./n

i=l * V

l " V

2

5. Q = B

*1 " h

The time over which the runs were calculated varied from six

seconds to over one minute so that the number of points, n, used to find

the average pressure ranged from 30 upwards. The developed head, H,

was adjusted for the velocity head in the 2-inch discharge, as well as for a fluid head term resulting from the placement of the pressure taps

7.2 Cavitation Tests

The cavitation tests were performed in a manner similar to the

performance tests with the following exceptions. Instead of the generator

and receiver being pressurized to one atmosphere, they were pressurized

to about 0„ 2 atmosphere , and the receiver ullage was connected to the

generator ullage. Immediately after the pump was started, evacuation

of the ullage spaces began. The test was terminated when severe cavitation occurred or when a low liquid-level sensor was reached,, Because

of the flow resistance of the 1-inch line through which the receiver ullage

was pumped, the receiver pressure lagged that of the generator. This

effect, coupled with the transients mentioned previously, sometimes

resulted in non- steady operating conditions before establishing cavitation.

12
8. Test Results

Table 1 summarizes the pump tests. The solid fraction of the

slush hydrogen varied from 0„ 19 to 0. 55. The average solid fraction was

0. 33. Although in most cases the slush was freshly made, two runs were

made with slush aged to six hours. No difficulty was experienced in pumping any of the mixtures regardless of the age or concentration.

8.1 Performance Characteristics

The performance data are presented in two forms; developed

pressure in psi versus capacity in gpm, figure 6; and developed head in

feet of fluid pumped versus flow in gpm, figure 7. Table 2 lists data

for each test

In general, the developed head for slurries in centrifugal pumps

is less than that for water [Stepanoff, 1957], However, Stepanoff [l9o3]

points out that the developed head for water slurries in feet of mixture

. . . "should be the same as that on clear water reduced only by the additional hydraulic losses caused by the presence of solids in the pump

passages." Since similar pipe line flow losses have been observed for

slush and triple-point liquid hydrogen, there should be no difference in

the developed head. This conclusion is confirmed by the close grouping

of the developed head data for liquid and slush in figure 7.

A statistical test of this agreement in the developed head for

liquid and slush was made by least squares fitting separate quadratic

curves to the liquid and slush data at each pump speed. The average

difference between the liquid and slush curves over the range of common

data was then used in a "Student" t-test. The percent confidence that

the head in feet of fluid pumped is the same for liquid and slush hydrogen

was 22. 8, 92. 6, 89. 5 and 88. 2 percent for the pump speeds of 8, 000,

11,000, 14,000 and 19,000 rpm respectively. The hypothesis that the

13
Table 1

Pump Test SummaryAccumulated Test Times

Electric Drive

Liquid

Slush

Turbine Drive

Liquid

Slush

Total Accumulated Time

17.5 minutes

14. 5 minutes

27. 7 minutes

19.3 minutes

79 o minutes

Number of Tests

Electric Drive

Liquid

Slush

Turbine

Liquid

Slush

Total Number of Tests

30

28

47

36

141

14
Table 2. Pump Performance Test Data

Triple - Point Liquid Hydrogen Slush Hydrogen

Run Pump Developed Developed Run Pump Developed Developed Solid No. Capacity Head

/ ft. of fluid\

\ pumped '

Pressure No Capacity Head

( ft. of fluidA

\ pumped /

Pressure Fraction

(gpm) (psi) (gpm) (psi)

Pump S peed = 8, 000 rpm

32 31.2 149. 5 4.97 34 62. 1 139.4 4.75 0. 261 36 64.9 139.3 4. 61 37 83.8 129. 2 4.39 0. 254

41 91. 127.6 4.20 38 132. 90. 2.99 0. 275

43 73.0 137.8 4. 55 39 91. 123.6 4. 16 0. 205

44 130. 92. 2 2.97 40 82.0 127.3 4. 32 0. 2 54 45 92. 122. 5 4. 03 42 53.0 143. 5 4.92 0. 296

47 100. 115. 3 3.78 46 124. 94. 5 3. 16 0. 292

49 58.0 135. 7 4.49 48 94. 114.9 3.94 0.391

65 57.8 139.0 4. 60 66 3 5.8 150. 4.98

Pump Sp eed =11, 000 rpm

10 104. 6 233. 7. 70 9 125.2 236. 1 8. 00 0. 246

11 115. 5 235.4 7. 77 12 131.9 221. 7 7. 52 0. 266

14 114.9 239. 7.89 13 104. 6 237.1 8. 08 0.265

16 54.8 273.7 9. 10 15 47. 1 270.9 9.21 0.219

19 149. 189.3 6. 18 24 86. 5 259. 3 8. 78 0. 188

23 7.8 290. 5 9.68 50 128.0 226.4 7. 88 0.491 * 70 67. 7 271. 9. 00 51 74. 253.4 8.95 0. 545 * 72 98.0 245. 6 8. 13 69 60.2 269.9 9.31 0. 327

74 100.4 237.8 7.87 71 69. 5 262.8 9. 15 0.419

76 121.1 220.7 7.29 73 78. 5 246. 6 8. 56 0. 398

110 66. 1 262.7 8. 76 77 173. 1 170.4 5.75 0. 356

112 74. 1 266. 8.86 114 77.8 256.9 8.89 0. 341

113 84.3 251, 8.35 117 94.9 233.4 8. 11 0. 398

115 93. 251.3 8.35 119 129. 1 229.7 7.90 0. 363

116 87.9 243. 8 8. 11 120 69.8 258. 7 9. 05 0.434

118 105.8 236.3 7.84 121 108. 233.9 8. 02 0. 292

123 82. 2 253.4 8.44 125 122. 1 225. 1 7.65 0. 341 124 96.7 243. 5 8. 09 127 113. 1 219.2 7. 56 0. 363

126 107.4 229. 1 7.60 129 148.4 187. 9 6.39 0. 327

130 149.8 189.3 6. 19 Pump Speed = 14, 000 rpm

52 82. 6 461.3 15.34 54 121.6 422. 2 14.36 0. 363

53 102.6 444. 14. 75 57 168.7 380.9 13. 01 0. 320

56 144. 404. 1 13. 36 58 180.9 326.0 11. 03 0. 256

59 159.2 362. 5 11.94 79 90. 3 457.4 15.87 0. 348

60 170. 5 377. 5 12.42 82 155. 5 404. 5 14. 01 0. 391

61 214. 266.3 8. 62 84 151.8 351.9 12. 23 0.426

62 194. 313. 1 10. 22 86 195. 2 357.2 12. 19 0.327

63 74. 1 430. 5 14.32 88 210. 6 317.4 10.75 0. 313 64 95.3 419.4 13.93 90 211.6 268.7 8.84 0.341

81 122. 1 426.0 14.12

83 160.8 391.2 12.90

85 172.3 336.4 11.04

87 199.. 4 342.4 11.20

89 217.0 315.8 10. 27

91 234.3 241.8 7.75

15
Table 2. Pump Performance Test Data (continued)

Triple - •Point Liquid Hyd:rogen Slush Hydrogen

Run Pump Developed Developed Run Pump Developed Developed Solid No. Capacity Head

ft. of fluid \ ^ pumped '

Pressure No. Capacity Head

,ft. of fluid\

> pumped '

Pressure Fraction

(gpm) (psi) (gpm) (psi)

Pump Speed = 19, 000

93 131.9 756.8 25. 16 92 135.6 755. 8 26. 28 0.398

95 179. 8 69 5. 7 23. 04 94 184.2 689. 5 23.64 0.313

97 245.3 656. 5 21. 58 98 224. 7 645. 6 22. 26 0.402

99 236. 8 635.8 20.90 100 262.8 617.2 20. 82 0. 256

101 2 54. 8 581.0 19. 03 102 304. 1 513. 3 17.24 0.313

103 320.4 48 5. 2 15. 64 106 214. 2 678.7 23.33 0.363

107 219.7 648. 1 21.36 108 229.7 634. 5 21.61 0.299

109 236. 7 639.4 21. 03

* Aged for 6 hours.

16
30

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Aged 5.8 hrs F-0.49

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8.000RPM

A

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I4.000RPM

O TRIPLE-POINT LIQUID HYDROGEN

A SLUSH HYDROGEN, AVG. SOLID

FRACTION, FAVG = 0.33

50 100 150 200 250

CAPACITY, gpm

300 350 400

Figure 6. Pump Performance Map, Developed Pressure

17
800

700

"S 600

Q.

5= 500

<

O

UJ

Q.O

_lUJ>

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400

300

200

100

8000 RPM

O TRIPLE- POINT LIQUID HYDROGEN

A SLUSH HYDROGEN, AVG. SOLID

FRACTION , FAVG = 0.33

50 100 150 200

CAPACITY , gpm

250 300 350

Figure 7. Pump Performance Map, Developed Head

18
developed head is the same for liquid and slush hydrogen was thus

accepted. The standard deviation of the measured values of the head was

3. 7 percent of the head.

In an alternative approach to the data analysis, Gross [ 1968] calculated the average solid fraction of the slush required to give an identical

developed head for liquid and slush. His calculated value for the average

solid fraction of 0. 31 is in excellent agreement with the average measured

value of 0.33.

In the time available, the pump motor a-c power was not measured

because of the complexity involved in measuring 6 lead, 3 phase, square

wave, 400 Hz, a-c power. However, the d-c power to the inverter was

measured and pump efficiencies based on these measurements are presented in figure 8. The no load inverter power of 0. 13 KW was subtracted

from the d-c power to correct for the inverter losses. Turbine windage,

bearing and seal losses reduced the efficiency of this modified pump

well below that expected from an unmodified unit without the turbine.

The agreement between the normal boiling point liquid, triple

point liquid, and slush efficiencies indicates that the pump was operating

normally in triple -point liquid and slush hydrogen, and that the pump

efficiency is unchanged when handling slush. This conclusion can also

be reached from the developed head data using Stepanoff's [1963] relationship,

H e m m

H

i

e

i

between the developed head, H, and the pump efficiency, e, for slurry

flow. Here the subscript m refers to the mixture and the subscript I,

to the liquid. Since no difference in H was observed between liquid and

19
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TRIPLE-POINT

LIQUID

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20
slush, no change in the efficiency when pumping slush hydrogen would

be expected.

8. 2 Cavitation Characteristics

Since in most applications it will be desirable to pressurize

hydrogen slush with helium gas, the cavitation tests were performed

with the mixture pressurized with helium. The variation in the operating

conditions prior to cavitation made picking the inception of cavitation in

some of the tests a matter of judgement. The greatest difficulty occurred

with the 11,000 rpm runs, since the torque- speed characteristics of the

motor resulted in only a small increase in speed with cavitation. With

the turbine drive the increase in speed was much greater (see figures

23-29 of the Appendix), and hence the cavitation inception point was more

easily determined. By using a 15 percent reduction in head as the

criterion for cavitation, the scatter in the NPSH was reduced, and the

comparison between liquid and slush was more easily made.

Figures 9 and 10 summarize the results of the cavitation tests.

Figure 9 presents Thoma's cavitation constant, a, for a 15 percent reduction in developed head versus the specific speed. Figure 10 presents

2 NPSH/N versus Q/N for a 15 percent reduction in developed head. No

difference in either a or NPSH requirements, expressed in feet of liquid,

for triple-point liquid or slush hydrogen is indicated.

Figure 11 summarizes the smoothed experimental curves of

NPSH versus the developed head, H, for 11,000 rpm. Figure 12 summarizes the 14,000 rpm cavitation runs, noting the pump speed as a parameter. Figures 13 through 29 of the Appendix are plots of the

individual data points for the cavitation runs.

21
.VJ

1

1 1 > 1 1 1 1 O TRIPLE-POINT LIQUID HYDROGEN , 1 1,000 RPM.

X ~~ A SLUSH HYDROGEN, 11,000 RPM.

x .04 • TRIPLE- POINT LIQUID HYDROGEN, ~ 14,000 RPM

SLUSH HYDROGEN,- 14,000 RPM.

Q_

Z —

iib .03 •

CAVITATION

CONSTANT,

2

g

A

•

k —

A

n c

2

i —

o*

1

1 1 A

1 1 1 1000 2000 3000 4000

SPECIFIC SPEED, ns

= H^/q / H*4

5000

Figure 9. Pump Cavitation Constant for a 15 Percent Reduction in

Developed Head

22
CM

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CCQ

>-X

9

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8

uj 3

_la.

iLU

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O TRIPLE-POINT LIQUID HYDROGEN, 11,000 RPM,

A SLUSH HYDROGEN, 11,000 RPM. • TRIPLE- POINT LIQUID HYDROGEN, ~ 14,000 RPM.

A SLUSH HYDROGEN, ~ 14,000 RPM.

aa

o

A A

8 12

Q/Nx I0 3

, gpm /rpm

20

Figure 10. Pump NPSH/N2 vs. Q/N for a 15 Percent Reduction in

Developed Head

23
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C\J C\J (\J <M CM — —

airrid do i33d 4 av3H Q3d0i3A3a

24

u_ o

o

1- 3

LU a. & UJ

u_ •

•* i—

i

X

CO

Q_ 3

<fr z • t-l ^

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1

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GO

ro

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toz

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z

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cr z

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roO

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CC

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>

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ii 1

.37

Q_

cro

2

Q.cro

o

cr2

Q.

cr

ro

1 z

3

1 <r

u.

* 1 °

11

Q

uj2 z

o 1 — 1

ro* 7

o

o

lO*\

i 0-

1 ££ iO

1 o

, 1 ro"

t i

SH

HYDROG

3

LE-P0INT

L

ID

FRACTIO 3 1 cr= i &.i

\. \ 7" 9 N 
 o i 3 = -J

1 ro °-

_i cr o

1

i

i >w <* ' co r- en — z 1 Ns. T 1 i ii 3

cr 1 XS I

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1 >w 1 2 1 _ \ Q-l I \ 1 cr I \ \\ —

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amid do i33d 4 av3H Q3dcn3A3a

25
8. 3 Pump Wear

The pump, which was still in operating condition at the conclusion of the tests, operated in slush hydrogen for 33.8 minutes out of a

total running time of 79.0 minutes. It was disassembled and all pertinent

components including the inducer, impeller, labyrinth and dynamic face

seals, and bearings were inspected. No sign of wear over that expected

from operation in liquid was observed.

;

9. Conclusions

Asa result of the pump tests with liquid and slush hydrogen the

following can be concluded.

1. Both aged and fresh slush hydrogen prepared by the freeze-thaw

process can be pumped by a properly selected conventional liquid hydrogen pump.

2. The developed head expressed in feet of fluid pumped is the

same for liquid and slush hydrogen.

3 The pump efficiency is unchanged when pumping slush hydrogen.

4. The NPSH requirements, expressed in feet of liquid, and the

cavitation constant, a, for helium pressurized slush and triple-point

liquid hydrogen are the same.

5. Slush hydrogen caused no additional wear to pump components

over that caused by liquid hydrogen during 33 8 minutes accumulated

with liquid-solid mixtures out of a total running time of 79.0 minutes.

10. Acknowledgments

The authors wish to express their appreciation to L. A. Gross,

C. D. Miller, and J. L„ Vaniman for their contributions towards the

successful completion of these tests.

26
1 1 . Re ferences

Gross, L. A., NASA -Mar shall Space Flight Center, Private Communication,

Mann, D. B. , P. R. Ludtke, C. F. Sindt, and D. B. Chelton (1966)

Liquid-Solid Mixtures of Hydrogen Near the Triple Point,

(Advances in Cryogenic Engineering 11 , K. D. Timmerhaus, Ed.

,

(Plenum Press, New York).

Mann, D. B. , P. R. Ludtke, C. F. Sindt, D. B. Chelton, D. E. Daney,

and G. L. Pollack (Unpublished Report).

Stepanoff, A. J., (1957), Centrifugal and Axial Flow Pumps (John Wiley

and Sons, New York).

Stepanoff, A. J. (Nov. 17-Z2, 1963), Pumping Solid-Liquid Mixtures,

Presented at ASME Winter Annual Meeting, Philadelphia, Pa. , ASME Paper No. 63-WA-102.

Weitzel, D. H. , C. F. Sindt, and D. E. Daney (1968), Hydrogen Slush

Density Reference System, Advances in Cryogenic Engineering

13, K. D. Timmerhaus, Ed., (Plenum Press, New York).

27
12. Appendix

Pump Cavitation Curves

28
. 300

<

LUX

Q

UJQ.O

_l

LU

>

LUQ

200

00

^

r

-%

OL

oo o ° o o o o

2 4 6 8 10 12 14 16 18

NPSH.FEET OF TRIPLE-POINT LIQUID HYDROGEN

Figure 13. Pump Cavitation Data - 11, 000 RPM. Triple-Point Liquid

Hydrogen, Run No. 123

r 300

<

LU

X

Q

LU

Q_O

LU

>

LUQ

200

100

—

1 1

1 —

03°

o

ooo o

o —

o

o

o

1

1

1 1

—

2 4 6 8 10 12 14 16 18

NPSH, FEET OF TRIPLE-POINT LIQUID HYDROGEN

Figure 14. Pump Cavitation Data - 11, 000 RPM. Triple -Point Liquid

Hydrogen, Run No. 124

29
~ 300

<

UJ

X

Q

UJ

Q.

3

UJ

>

UJQ

200

100

—

1

1 1 —

—

©o°<

r> oo o O o —

o

o

o

o

1 _L 1 2 4 6 8 10 12 14 16 18

NPSH, FEET OF TRIPLE- POINT LIQUID HYDROGEN

Figure 15. Pump Cavitation Data - 11, 000 RPM. Triple -Point Liquid

Hydrogen, Run No. 126

<

UJX

Q

UJ

Q_

3

UJ

>

UJQ

r 300

200

100

1 1

1 —

I

\ (r jO© oo G o

—

I Sit

— o —

1

o

o

1

, 2 4 6 8 10 12 14 16 18

NPSH, FEET OF TRIPLE-POINT LIQUID HYDROGEN

Figure 16. Pump Cavitation Data - 11, 000 RPM. Triple -Point Liquid

Hydrogen, Run No. 128

30
<

X

O

Ld

Q_O

-J

Ld

>

LdQ

300

200

1 1 1 —

— —

"

I J

1

,

o

1

o o

1

—

100

2 4 6 8 10 12 14 16 18

NPSH, FEET OF TRIPLE -POINT LIQUID HYDROGEN

Figure 17. Pump Cavitation Data - ll,0OORPM. Triple-Point Liquid

Hydrogen, Run No. 130

<

LdX

Q

Ld

Q_O

_J

Ld

>

LdQ

300

j 1 1 —

<£t) go o

o —

200 O

O

inn

o — o

$

1 11

—

2 4 6 8 10 12 14 16 18

NPSH, FEET OF TRIPLE-POINT LIQUID HYDROGEN

Figure 18. Pump Cavitation Data - 11, 000 RPM. Slush Hydrogen,

Run No. 121, F = 0.29

31
. 300

<

LJ

X

Q

UJ

a.o

-J 200

LU

>

LUQ

!00

1 1 1 —

) o oooo o —

— O

1 1 1

—

2 4 6 8 10 12 14 16 18

NPSH.FEETOF TRIPLE-POINT LIQUID HYDROGEN

Figure 19. Pump Cavitation Data -11, 000 RPM. Slush Hydrogen,

Run No. 12Z , F = 0. 33

- 300

<

UJX

Q

UJ

Q_

3

UJ

>

UIQ

200

100

~T 1 1 —

G

©0 G

> G Q G

— G

G

G

1 1

1

1

—

2 4 6 8 10 12 14 16 18

NPSH,FEET OF TRIPLE-POINT LIQUID HYDROGEN

Figure 20. Pump Cavitation Data - 11, 000 RPM. Slush Hydrogen,

Run No. 125, F = 0. 34

32
~ 300

<

LlI X

Q

UJ

Q.

3

UJ

>

UJQ

200

00

1 1 1 1 —

wdOOOO o o

—

1

oo©

(

1 _L _L

—

2 4 6 8 10 12 14 16 18

NPSH, FEET OF TRIPLE- POINT LIQUID HYDROGEN

Figure 21. Pump Cavitation Data - 11, 000 RPM. Slush Hydrogen,

Run No. 127, F = 0. 36

. 300

<

UJX

Q

UJ

Q_

3

UJ

>

UJQ

200

100

1 l 1 —

— —

o

9

o o

I

o

1

—

2 4 6 8 10 12 14 16 18

NPSH, FEET OF TRIPLE-POINT LIQUID HYDROGEN

Figure 22. Pump Cavitation Data - 11, 000 RPM. Slush Hydrogen,

Run No. 129, F = 0. 33

33
500

<

UJX

Q

UJ

CL

3

UJ

>

UJQ

400

300

200

O DEVELOPED HEAC

A RPM

cfig O

O A

- 22

24

ro 20 O

18

Q_

16 Z

- 14

2 4 6 8 10 12 14 16 18

NPSH-FEET OF TRIPLE- POINT LIQUID HYDROGEN

12

Figure 23. Pump Cavitation Data - Approximately 14, 000 RPM. Triple-Point

Liquid Hydrogen, Run No. 134

500

Q

ui 400

X

Q

UJ

Q_

3

£ 300

UJQ

200

O O

^

a

aa a

-Q_

O DEVELOPED HEAD

A RPM

- 22

24

ro 20 O

- 18

CLor 16

- 14

2 4 6 8 10 12 14 16 18

NPSH-FEET OF TRIPLE-POINT LIQUID HYDROGEN

12

Figure 24. Pump Cavitation Data - Approximately 14, 000 RPM. Triple-Point

Liquid Hydrogen, Run No. 136

34
500

<

UJ

o

UJ

O

400

Ul

> 300

UJQ

200

1 1 6 DEVELOPED HEAD

A RPM

— —

— O °

o

J_

O

^A

3

1

A *

_L

A _

24

22

20 O

X

18

2

Q.

16

•«

14

2 4 6 8 10 12 14 16 18

NPSH, FEET OF TRIPLE-POINT LIQUID HYDROGEN

12

Figure 25. Pump Cavitation Data - Approximately 14, 000 RPM. Triple -Point

Liquid Hydrogen, Run No. 138

500

<

Ul

X 400

Q

Ul

Q_

3

Ul

2i

30°

200

O DEVELOPED HEAD

A RPM

cspcoo

A

O

A^O

a

^AA,A A

O O O

AA A

24

22

ro 20 2

X

18 Q_

or

•» 16 Z

14

2 4 6 8 10 12 14 16 18

NPSH. FEET OF TRIPLE-POINT LIQUID HYDROGEN

Figure 26. Pump Cavitation Data - Approximately 14, 000 RPM. Triple-Point

Liquid Hydrogen, Run No. 141

35
500

Q

<

UJX 400

Q

UJ

CLO

_l

UJ

> 300

UJQ

200

~r 1 6 DEVELOPED HEAD i A RPM

—

A O30Q © O !

—

£&

G

V

—

—

Q

O

1

A

AA A

_L

^ A

A A

1

A

1

24 - 22

ro 20 2

18 £

en

16

14

2 4 6 8 10 12 14 16 18

NPSH, FEET OF TRIPLE-POINT LIQUID HYDROGEN

Figure 27. Pump Cavitation Data - Approximately 14, 000 RPM. Slush

Hydrogen, Run No. 135, F'= 0.37

500

Q

<

UJ

X

Q

Ul

Q.

3

UJ

>

UlQ

400

300

200

A

O DEVELOPED HEAD

A RPM

.000-

t

G°

AaaaA A A& a

GD © O

A

24

22

ro 20 2

18 £

or

16 — 14

2 4 6 8 10 12 14 16 18

NPSH, FEET OF TRIPLE-POINT LIQUID HYDROGEN

12

Figure 28. Pump Cavitation Data - Approximately 14, 000 RPM. Slush

Hydrogen, Run No. 139, F = 0. 38

36
400-

<

Q

LU

Q.

3

LU

300

> 200

LUQ

100

1

1 6 DEVELOPED HEAD

A RPM

— —

—

A

A O

A

o o oo O

—

G

O

1

A^AA

1

A

A AA

1

A

1

24 — 22

ro 20 2

18 Q_

or

14

2 4 6 8 10 12 14 16 18

NPSH, FEET OF TRIPLE-POINT LIQUID HYDROGEN

Figure 29. Pump Cavitation Data - Approximately 14, 000 RPM. Slush

Hydrogen, Run No. 140, F = 0. 30

GPO 842 - 823 37

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