NBSIR 74-366

STUDY OF CRYOGENIC PROPELLANT SYSTEMS

FOR LOADING THE SPACE SHUTTLE

R.O. Voth, W.G. Steward, and W.J. Hall

Cryogenics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

Interim Report

April 1974

Prepared for

National Aeronautics and Space Administration

John F. Kennedy Space Center

Kennedy Space Center, Florida 32899

NBSIR 74-366

STUDY OF CRYOGENIC PROPELLANT SYSTEMS

FOR LOADING THE SPACE SHUTTLE

R.O. Voth. W.G. Steward, and W.J. Hall

Cryogenics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

Interim Report

April 1974

The results of this report are not to be used for advertising or promotional purposes, or to indicate endorsement or disapproval

of the product(s) by the National Bureau of Standards,

Prepared for

National Aeronautics and Space Administration

John F. Kennedy Space Center

Kennedy Space Center, Florida 32899

U.S. DEPARTTy/IENT OF COMMERCE. Frederick B. Dent. Secretary

NATIONAL BUREAU OF STANDARDS. Richard W Roberts. Director

CONTENTS

Page

1, Introduction 1

1. 1 Objectives 2

2, Graphic Display Computer Terminal 4

2, 1 Description of Equipment 4

2, 2 Description of the Minicomputer Software .... 4

2. 3 Instructions for Log -In 10

2. 4 Instructions for Initiation of Computation in

the Automatic Mode 12

2. 5 Reloading the Minicomputer Programs 15

3, Computation Options --Cooldown Period 17

3, 1 Option 1 - Thermal Stresses - calculates stresses

due to rapid cooldown of flanges, or bowing of

pipeline due to stratification in the case of low

flow rates 17

3. 2 Option 2 - Valve Opening Surges - surges due

to rapid vaporization when a valve is opened

preceding a free wheeling pump. Also calculated

is the peak due to water hammer as the liquid

impinges on a free wheeling pump 19

3. 3 Option 3 - Cooldown Time - length cooled down,

flow rate, and pressure drop across the ptimp

versus time 24

3. 4 Option 4 - P\imp Start-Up Cooldown Surges - surges due to rapid vaporization when a pump

is started upstream from a warm line 30

iii
CONTENTS (Continued)

Page

4. Computation Options --Post-Cooldown Period 34

4. 1 Option 5 - Water Hammer - pressure spikes due

to water hammer when valves are closed in a flowing liquid stream 34

4. 2 Option 6 - Cold Flow - steady flow operation

and transient response to changes in operating

conditions 39

5. General References 50

5. 1 System Reference Manuals 51

APPENDIX A. Heat-Mass Transfer Correlations for

Uninsulated LOX Transfer Lines 52

APPENDIX B. Cooldown Surge 72

APPENDIX C. Loading of the Minicomputer 85

iv
LIST OF FIGURES

Page

Figure 1. Graphic display terminal and mini -computer . . 5

Figure 2. Log-in sequence 11

Figure 3. General input data 13

Figure 4. Selection of computation options 16

Figure 5. Option 1 - Thermal stresses input display ... 18

Figure 6. Option 2 - Valve opening surges input display . 20

Figure 7. Option 2 - Valve opening surges input display

(continued) 21

Figure 8. Option 2 output 23

Figure 9. Option 3 - Cooldown time input display 25

Figure 10. Option 3 output 27

Figure 11. Option 3 output (continued) 28

Figure 12. Option 3 output (continued) 29

Figure 13. Option 4 - Pump start-up cooldown surges

input display 31

Figure 14. Option 4 output 33

Figure 15. Option 5 - Water hammer input display 35

Figure 16. Option 5 - Water hammer input display

(continued) 36

Figure 17, Option 5 output 38

Figure 18. Option 6 - Cold flow input display 41

Figure 19. Option 6 - Cold flow input display

(continued) 42

Figure 20. Option 6 output 44

Figure 21. Option 6 output (continued) 45

Figure 22. Option 6 output (continued) 46

Figure 23. Option 6 output (continued) 47

V
LIST OF FIGURES (Continued)

Page

Figure 24, Option 6 output (continued) 48

Figure 25, Option 6 output (continued) 49

Figure Al, Comparison of calculated (dashed lines) steadystate heat flvix with the experimental data of

- Richards, et al. [1962] for liquid nitrogen

cooled test section 66

Figure A2, Comparison of calculated steady state heat flux

with the experimental data of Ruccia and

Mohr [I960] for a liquid oxygen cooled vertical

cylinder 45. 7 cm (18 in) OD x 6. 71 m (22 ft)

long 69

Figure Bl. Peak surge pressure for liquid nitrogen in a 6 1 m

(200 ft), 1. 6 cm (0. 625 in) OD copper tube

transfer line 80

Figure B2. Peak surge pressure for subcooled nitrogen in a 46 m (150 ft), 1. 6 cm (0. 625 in) OD copper

transfer line 81

Figure B3. Peak surge pressure for liquid nitrogen in a

25 m (82 ft), 1. 6 cm (0. 625 in) OD copper

transfer line 82

Figure B4. Peak surge pressure for liquid nitrogen in a

7. 6 m (25 ft), 1. 6 cm (0, 625 in) OD copper

transfer line , 83

Figure B5, Peak surge pressure for liquid hydrogen in a 61m (200 ft), 1. 6 cm (0. 625 in) OD copper

transfer line 84

vi
LIST OF TABLES

Page

Table Al. Calculated steady state heat flux for the

experimental conditions of Richards,

et al. [1962] 65

Table A2. Summary of heat flux calculations calculated

for the experimental conditions of Ruccia and

Mohr [I960] 68

vii

Study of Cryogenic Propellant Systems for Loading

the Space Shuttle*

R. O. Voth, W. G. Steward, and W . J . Hall

Computer programs have been written to model the liquid

oxygen loading system for the space shuttle. The programs allow

selection of input data through graphic displays which schematically

depict the part of the system being modeled. The computed output

is also displayed in the form of graphs and printed messages . Any

one of six computation options may be selected. The first four of

these pertain to thermcil stresses, pressure surges, cooldown times,

flow rates and pressures during cooldown . Options five and six

deal with possible water hammer effects due to closing of valves

,

steady flow and transient response to changes in operating conditions

after cooldown.

Procedures are given for operation of the graphic display

unit and minicomputer.

Key words: Computer modeling; cooldown; cryogenic flow; stresses;

svirges; transient flow; water hammer.

1 . Introduction

This is a final report under NASA Contract No. CC- 0342 OA.

Loading of the space shuttle with liquid oxygen, using the existing

ground support equipment at the Kennedy Space Center (KSC) , will require

alterations in the current cooldown and loading procedures . Also minor modifications of the existing loading system may be required. Since acceptable

loading rates, minimum loading times, and liquid capacities for the shuttle

have not been fixed, the loading procedure and loading sequence has not been

determined . Even after the shuttle capacities , etc . , have been determined

,

* This work was conducted at the National Bureau of Standards under the

sponsorship of Kennedy Space Center - NASA.
changes to the loading procedure will probably occur as experience is gained.

Any changes in the cooldown procedure can cause excessive cooldown pressure

spikes and/or excessive temperature induced stresses in components of the

ground support system during the cooldown period. Also, flow rates of both

liquid oxygen and vented gaseous oxygen during loading operations that follow

cooldown are important . The study supplies the necessary mathematical and

system analysis and hardware and computer software so that any proposed

cooldown and loading sequence can be simulated; thus, the consequences

and/or benefits of siltering established procedures can be determined before

a wet test of the system is initiated. The present study is for the liquid oxygen

system

1.1 Objectives

The objective of the study is to supply the KSC with the necessary

analysis, hardware, and computer software to provide a computerized model

of the liquid oxygen system. By means of these programs, cooldown and loading procedures can be checked mathematically to determine thermal stresses,

cooldown pressure surges, cooldown times, and loading rates before a wet

test of the actual system is conducted . This work is an extension of a recently

completed study in which a mathematical model of the 35. 6 cm (14- inch) cross

[country piping system was developed for the calculation of cooldown pressure

surges. Specific objectives are:

(1) Purchase of a graphical display unit with the hardware necessary

to interface the display \anit with an existing computer at KSC

2
(2) Develop a mathematical model and computer program to

calculate thermal stresses in major components of the ground support

equipment during the cooldown period. The major components include

the liquid oxygen pumps and other massive components such as pipe

flanges.

(3) Develop a mathematical model and computer program to calculate

cooldown times for the various configurations of the ground support equipment.

(4) Develop a mathematical model and computer program to

calculate flow rates and pressures at selected points on the ground

support equipment after the cooldown period. The flows and pressures

shall be related to pump speed, supply tank liquid level, system configuration, and valve characteristics.

3
2. Graphic Display Computer Terminal

2. 1 Description of Equipment

The system consists of a graphical display terminal interfaced

with the KSC time share computer through a 8000 word storage minicomputer and MODEM. Figure 1 shows the graphical display unit and

minicomputer.

Software for communication between the display \init and the KSC

computer, routines for schematic displays, input-output, and graphing

are programmed into the minicomputer. These routines are also stored

on punched paper tape from which they may be reloaded if necessary.

The programs and subroutines used in the calculations are catalogued

in the KSC computer and are called as needed through the minicomputer

software routines.

2. 2 Description of the Minicomputer Software

The programs contained in the minicomputer control the information flow between the graphical display unit and the KSC timesharing

computer. Besides the control function, the minicomputer has the input

schematics with the associated input data and programs to interpret the

responses received from the KSC timesharing computer (during execution

of the oxygen grotind support computer program) in its memory.

The communication between the minicomputer system and the

KSC computer is carried over a high speed telephone data line. The

MODEM properly conditions the signals for the high speed data

transmission.

Data is transmitted in various sized blocks. Each character of

data in the block is accompanied by a parity bit and each block of data

is accompanied by a parity character to make the parity of each word

and parity of the entire block being transmitted correct. The receiving

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returned to the sending station. If the parity of the received information

is not correct, due to noise or other problems with the telephone line,

the receiving station requests a retransmission. The sending station

will then automatically retrajismit the data. In some rare instances,

the retransmission request is lost and the data must be maunually

retransmitted. ^|

The minicomputer software has two basic modes of operation

using the graphical display keyboard. The first mode, termed the

manual mode, allows conversation with the KSC computer in a manner

similar to a normal teletype except that the communication is at high

speed. The second mode of operation, termed the automatic mode, is

used to run the computer programs simulating the oxygen ground support

equipment. Much of the communication between the minicomputer and

the timesharing computer in the second mode is automatic, with no

operator input required.

During operation in either mode, the graphical display terminal

will emit an audible "beep" whenever an acknowledgment is received

from the timesharing computer. This "beep" will inform the operator

that a data block has been successfully sent and new information can be

entered or a return can be expected from the timesharing computer.

Until a successful transmission is affected, the keyboard of the graphical

display unit is locked except to a control B , as explained in a later

paragraph.

Operation in the manual mode allows for normal log -in procedures

and the use of any subsystems on the KSC computer. Fortran, basic

or the editing subsystem, may be employed in the manual mode.

6
Since the graphical display -minicomputer combination is connected

to the Datajiet-760 terminal of the KSC timesharing system, operation in

the manual mode is very similar to the general operation of the Datanet

system as described in the Honeywell manual [1971]. * Log-on procedures

as described for the Datanet are also valid for the graphic display unit.

During operation of the graphics unit, data entered on the screen

of the graphics display are also entered into the memory of the minicomputer ajid when a carriage return is depressed, the data from the

computer memory is transmitted to the timesharing computer. More

than one line of data may be transmitted in a block if each line entered

on the screen is terminated by a line feed and the entire block is terminated by a carriage return for transmission.

Typing errors can be corrected by using a control A which causes

the cursor to be backspaced once cind lowered one line. The character

typed in the lower position replaces the original character in the minicomputer memory and will be transmitted when the carriage return is

depressed. Since the graphics display unit is connected to the Datanet760 terminal, other characteristics unique to the Datanet system effect

the operation of the display xmit. As an example, the timesharing computer counts the lines of output during its data transmission and after

sufficient lines have been sent to fill the screen of a Datanet-760 system,

data transmission is terminated. The stop in data transmission is

indicated by the ASCII code characters A * on the screen of the graphics

unit. To receive additional data, the operator must transmit a blank

line by depressing the carriage return on the keyboard.

The automatic mode of operation interacts with the specific oxygen

system simulation programs available in the Fortran subsystem of the

timesharing computer. During automatic operation, the minicomputer

* Identification of a manufacturer and a manufacturer's product has

been necessary to msike the results of this work meaningful and in no

way implies a recommendation or endorsement by the National Bureau

of Standards. _
will request a run of a specified program, send the required data when

an equal sign is received, and interpret and display returning data from

the timesharing computer on the graphical display unit. Usually, the

returning data will be displayed in graphical form. Since the oxygen

simulation programs are in the Fortran subsystem, the KSC computer

must be in the Fortran subsystem before the automatic mode of operation is entered with the graphical display unit. The Fortran subsystem

of the timesharing computer is indicated by an asterisk displayed on

the screen.

Several control characters are used during normal operation of

the graphic display unit to help the operator during the execution of the

various programs. A control character is used during communication

between the graphic display unit and the minicomputer and need not

be followed by a carriage return to effect a transmission. A control

character is executed by depressing and holding down the control key

on the keyboard and then depressing the desired alpha-numeric key.

Thus, a control D means that the control key was depressed and held,

and then the letter D was depressed. The following is a description of

the control characters available for use on the graphic display unit.

Control A; Control A allows the operator to correct a typing

error before a block of data is sent to the timesharing computer. Any

time before the carriage return is depressed, a change can be made

to previously typed material. This change is made by depressing the

control A an appropriate number of times until the cursor is located

below the character to be changed, entering the new character and

then proceding to enter subsequent characters in the line.

8
Control B: Depressing control B will cause the minicomputer to

issue a $*$ BRK command to the timeshare computer and return the

minicomputer to the manual mode of operation. The function of the

$'!^$BRK command is described in the Honeywell Information Manual [1971]

Control B can be used any time even during a trcinsmission when the

keyboard is locked to other input.

Control G: Control G causes the minicomputer to enter the

automatic mode of operation. Entering the automatic mode of operation

should not be attempted unless the KSC timeshare computer is operating

in the Fortran subsystem and an asterisk (*) is displayed as the last

received character on the graphic display unit.

Control P: Depressing the control P causes the minicomputer

software to interpret data returning from the timesharing computer into

graphical output. This option was supplied with the minicomputer to

allow graphical output from any Fortran programs written in the manual

mode. In order to graph the results of any program written in the

manual mode, the output from the program must be supplied to the

ASCII coded Fortran subroutine called PLOT currently available on the

timesharing computer. Along with the data, labeling information can

also be supplied to PLOT. The program DEMO currently loaded in the

timesharing computer can be listed to obtain instructions on how to use

subroutine PLOT. After writing a program for which a graphical output

is expected the program is run in the manual mode, except that after

all input data has been supplied and an acknowledge received as

indicated by a "beep;" control P should be depressed. A graph of the

returning data will then appear on the graphical display unit.

9
2. 3 Instructions for Log-In

The log-in routine for the minicomputer is accomplished in the

manual mode. The procedure is to turn on the Modem (switch located

inside the front cover), the minicomputer (key switch on front panel),

and the graphics display unit (switch located on the front of the pedestal

below the keyboard). The line -local switch on the graphics display

keyboard should be set to line. After a short warm-up period, the

screen on the graphics display unit will light up. The page key on the

display unit shotild be depressed to prepare the screen for reception

of messages. The starting address of the software program in the

minicomputer is 00002 in octal (switch 14 on the top row of toggle

switches up, all others down). After setting the top switches to the

starting address, depress RESET cind then START on the momentary

contact control switches from the lower row of switches of the minicomputer. The timesharing computer can now be dialed on the telephone. After the computer carrier signal (a continuous tone) is

confirmed, the telephone data switch can be actuated. As soon as the

minicomputer software confirms the computer interconnection, the

words PLEASE LOG IN will appear on the graphics display screen. If

these words do not appear, a fault has developed in the minicomputer

software, or the telephone interconnection was not achieved. The

program should be reloaded as described in appendix C. The normal

log-in procedure for the Datanet 760 system as described in the

Honeywell manual [1971] can now proceed. A carriage return should be

supplied after each input to transmit the information to the timesharing

computer. Figure 2 shows the appropriate log-in sequence as it would

appear on the screen of the graphics display unit. Computer supplied

messages are underlined.

10
PLEASE LOG IN

$>!=$MD PASSWD, 26, DAC, TSS

>:c>;c>!c^»^ CONNECT REQUEST SENT TO CP >!<>:^»>!»;<>}c KSC 635 AT CIF ON 03/06/74 AT 10. 281 CHANNEL 4424

USER ID - 3MX002

PASSWORD-

NBS

9 BLOCKS FILE SPACE AVAILABLE

**TSS SIZE 54K CARDIN 25K

SYSTEM ? FORT

OLD OR NEWNEW

READY

Figure 2. Log-in sequence.

11
2. 4 Instructions for Initiation of Computation in the Automatic

Mode

In order to perform calculations in the automatic mode using the

oxygen simulations programs, the Fortran subsystem of the timesharing computer must be available. On figure 2, the Fortran subsystem was entered by entering Fortran for the required system and

new for the type of program. After an asterisk (*) appears on the

screen as the last reception, control G can be depressed to enter the

automatic mode of calculation. After initiation of the automatic mode,

the universal figure (fig. 3)^ will appear on the screen of the graphics

terminal. This figure is used to define the general characteristics of

the piping system.

Pipe lengths under Entry 1 in the General Input Data may include

equivalent length to acco^mt for the added restrictions of pipe fittings,

filters, or other restrictions. If this is done, the pipe wall thickness

entered into the specific input data of option 3 must be altered correspondingly in order to provide the correct mass of material to be

cooled down. Entry 7, "Supply Ullage Pressure" requires some clarification. For computation options, except option 6, there is no differentiation between the ullage pressure during storage and during the transfer process. For option 6, the pressure specified in the general input

data is taken to be the ullage pressure during storage and it is assumed

that the supply liquid becomes saturated at that pressure. The specific

input data for option 6 allows a "Supply Ullage Pressure During Transfer"

to be selected which may be different from the ullage pressure during

storage.

When the figure appears, the input variables will contain the

numbers used in the previous run of the program. Any or all of the

The figures shown here are actual photographs of the graphic display

as they will appear during operation of the system.

12
13
input numbers may be chaoiged. A change is accomplished by moving

the horizontal cursor to the line containing the number to be changed,

pressing the "RUB OUT" key, then typing the new number in the blank

space which will appear. After pressing "RETURN" the operator may

move the cursor and make further changes. Even though the schematic

will not change, the computer programs will accept zero for lengths 4

and 5 (I-i4, L5) to eliminate the vertical rise if desired and will accept

a single pipe length equal to the total pipe length and a single diameter.

At the upper right on the figure, the current date and time will appear.

This date and time will remain the same and will appear on all subsequent figures to be used as an identification number to correlate hardcopy output. After all input parameters have been adjusted to acceptable

values, and the ALT MODE key is depressed, the system will proceed

to the next page.

This page (fig. 4) allows a choice of the computer program to be

run with the previous input data. After this choice is made by placing

the option number in the appropriate blank and depressing ALT MODE,

the terminal will display the first page of that option. The first page

of each option, plus as many as two more pages will appear, allowing

for more specialized input data. Typical display figures are shown in

the following sections. After the input data has been adjusted as previously described and ALT MODE depressed for each input figure,

the output of each option will appear after a short period of time.

During this time interval, several "beeps" will be heard as input data

is supplied to the timesharing computer. In some instances, when

multiple output is expected, a choice of output curves will be made

available. Each output curve will fill the entire screen. When the

output curve appears, it will be possible to make a hard copy and/or

digitize any point on the curve by placing the vertical cursor on the

desired point and depressing the space bar.
Restarting with the input display is accomplished by depressing

ALT MODE. At this time the operator may choose another computation

option with the previous input values, he may change the input, or he

may terminate computation by selecting option 7 from the second page

(RETURN TO MONITOR). Of course, if the operator chooses to start

calculations on a new system, a new date and time will appear on all

figures, allowing him to maintain correlation between the input and

the output figures,

2. 5 Reloading the Minicomputer Programs

Several paper tapes have been supplied with the system. Some

of the tapes were supplied by the manufacturer of the minicomputer

and can be used to debug the hardwired functions of the minicomputer.

The function of the manufacturer's supplied tapes are described in

accompanying literature. Other paper tapes can be used to reload the

existing minicomputer program. The paper tape loading procedure,

using an appropriate teletype unit, is described in Appendix C.

15
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3. Computation Options—Cooldown Period

3 . 1 Option 1 - Thermal Stresses

Calculates stresses due to rapid cooldown of flanges, or bowing of

pipeline due to stratification in the case of low flow rates

3.1.1 Applications

This computation determines low and high limits of flow rates during

cooldown from the standpoint of the resulting stresses in the piping system

and flanged joints. For very high flow rates and rapid cooling excessive

thermal stresses may be created in flanges due to the large radial temperature gradients . On the other hand very low flow rates might result in

stratified flow with liquid lying along the bottom of the pipe. The resulting

circumferential temperatiire gradients covild cause a pipeline to bow significantly

3.1.2 Input Data Entries

Section 2.3 describes the general log-in procedure for the graphic

display system. After the initial log-in has been accomplished, and Option 1

has been selected, a display similar to figure 5 appears. The input required

for this option in addition to the general input data of figure 3 is shown in

figure 5 . These are the outside diameter of the pipe fleinge, the outside and

inside diameters of the pipeline and the material of the pipeline

3.1.3 Output

The output for this CeJculation is alpha numeric only but will be displayed on the screen just as other output data. The values given

will be the maximum cooldown flow rate which will allow the stress in the

flanges to remain below the yield point, and the minimum flow rate which will

prevent stratified flow from occurring with the given input conditions

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3.2 Option 2 - Valve Opening Surges

Surges due to rapid vaporization when a valve is opened preceding a

free wheeling ptimp , or water hajnmer as the liquid impinges on a free wheeling

pump

.

3.2.1 Applications and Limitations

This computation applies to the opening of a valve preceding a warm

section of pipe and a pump . It computes pressure surges which might develop

from one of two causes: (1) rapid vaporization in the warm pipe (model

discussed in Appendix B) , or (2) a water hammer effect due to impingement

of liquid on a free wheeling pump. When the vaporization surge

occurs, it is accompanied by a slowing or reversal of the liquid flow so that

the water hammer would not occur or would be greatly diminished. The

program estimates the time at flow reversal due to vaporization and the time

of liquid impingement at the piamp in order to determine which of the two kinds

of surges to compute . Details of the computation of these pressure surges and

a computer listing of program VOS are given in Supplement A (1974), The

derivation of the pressure surge correlation is given in Appendix B.

3. 2, 2 Input Data Entries

Section 2,3 describes the general log-in procedure for the graphic

display system. After the initial log -in has been accomplished and the

Option 2 has been selected, first a display similar to figure 6 appears

and after ALT mode is depressed figure 7 will appear. If desired, input

variables may be examined and changed in the display as explained in

Section 2. 4, The variables in figure 6 and 7 apply only to Option 2 and

are in addition to those of the general input data of figure 3.

19
LtP7

••X iLj

Li: CO

Ij

i-J -2: i ^

cog

ui

LL. . .o

yji-i —• !—

- .o

1^

UJ

LiJ

LjJ iii CO

LU

u_O

LiJ l£O

UliJ CD

UJ

h-<L

LU

I—

T-i

UJ

in

14 .-^

-Jl±j UJ Ct: i-O

UJU-

-JLlJ LL UJ o

O-J

z:a oxcj! o:> Id

Ui

i_i CO

ZjCO

UlliJui

5: CO

t_iCO

_iyj

a;

liJUJ z:l3

LiJ _J.

CO UJ _!

UJX-CE

UJOO

iilUJi— ! -1

UJLj

liiUJ Q. CO LU©

!J3 Si

:I f _J

_i CO

UJ -. EILU

u_ -0

QXOUJ

EIQ- • i-J

T-i IjJ UJO

xu_

i-<UJ

Lii ^z:

UJ

-:Xa 1 i -J Q -cl : •;X !-< ii." '

'a,

J-)

CO

(Um

OX) a

(pa.o>.—

ni >

00oO

20
0)

Ofi

tn

"S

tuPho>>1 d O 0 O o

0)d

OjO • l-l

21
3. 2. 3 Output

The output of the computation is a graph of peak surge pressure

as a function of valve opening time. A typical example is shown in

figure 8, As the valve opening time is shortened, the peaks increase

to a maximum amplitude at a critical value of the opening time, as

discussed in Appendix B. Further decrease in the opening time has no

effect on the peaks. The maximum pressure and corresponding critical

opening time are indicated in the graph. If the water hammer surge is

applicable, no graph is displayed, but a single amplitude of the pressure

spike is given.

22
23
3. 3 Option 3 - Cooldown Time - length cooled down, flow rate,

and pressure drop across the pump versus time.

3. 3. 1 Application

As a cryogenic liquid flows or is pumped from a reservoir into a warm pipeline, vapor forms at the leading end of the liquid stream.

Frictional resistance to the flow of this vapor is the principle limiting

factor in the rate of cooling pipelines of large length- to -diameter ratios.

The slow moving liquid is evaporated and vapor is warmed to near the

initial temperature of the pipe in a short distance relative to the length

of pipe. When the pipeline is uninsulated, the heat transfer to the cold

part of the pipe adds to the vaporization rate and thus further retards

the progress of the liquid. The cooldown model based on this cold

front concept and listing of the computer subroutine (CDT) are discussed

in Supplement A (1974). The heat-mass transfer correlations are

discussed in Appendix A.

3. 3. 2 Input Data Entries

Section 2. 3 describes the log-in procedure for the graphic display

system. After the initial log-in has been accomplished and option 3

"Cooldown Time" has been selected, a display similar to Figure 9

appears. If desired, input variables pertinent to the cooldown time

computation may be viewed and changed on this display as explained

in Section 2. 4. The variables in figure 9 apply only to Option 3 and

are in addition to those of the general input data of figure 3. As

discussed in Section 2. 4, if equivalent pipe lengths have been added to

account for line restrictions, the pipe wall thickness should be decreased

correspondingly such that the total mass of material remains unchanged.

Concentrated masses such as valves, pumps, and fittings should be

compensated for by specifying additional pipe wall thickness provided

the calculated cooldown time desired is to include the time needed to

completely cool these concentrated masses.

24
h-i- U_Liu_Ii_ 1 I— I— f- 1- j— I— , Li_r---!Li. • -li-u-liIPs s? r- 111 ® Si : -J rr ^ i-i) w rt OJ C'-J C'4 i

_l _j _j_J -1-1 -J

fvCO.

CDHOi

H z:< •H-UJ

I«M<E li i

n LU :>-

£Li-:

:xuJo:

H-O

-Jl i-iu:

10 • J £L i Q

' (I

\

• UJ CO!

' II 3:

IDCO_J

o:>uje:<

I a. _] o

I <i

:-JO£L

i !—» I—

i3_J0_>

i

1 1- Lu

-_J_JX

:iLO.iliLu.

i 15 Z> CO I

; CO CO >-» i

25
3.3.3 Output

The outputs of the computation are: (1) Length Cooled Down versus

Time, (2) Flow Rate of LOX versus Time, and (3) Pressure Drop across the

Pump versus Time. Typical examples are shown in figures 10, 11, and 12.

26
:3

o

O

0)

27
28
aaooddo

COO

p-i u

Oh O

(Ud

29
3 . 4 Option 4 - Pump Start-up Cooldown Surges - surges due to rapid

vaporization when a pump is started upstream from a warm line.

3.4.1 Application

The computation applies to the starting of a pump in a line which is

partially or totally warm . By the correlation discussed in Appendix B it

computes pressure surges due to rapid vaporization when liquid enters a warm

line

3.4.2 Input Data Entries

Section 2 . 3 describes the general log-in procedure for the graphic

display system. After the initial log-in has been accomplished and the

Option 4 has been selected, a display similar to figure 13 appears. If desired, the input variables may be examined and changed in the display as

explained in Section 2 .4 . Only two variables , length of cold line and final

pump RPM , are shown in this display. The remaining values for this calculation were taken from the general input data of figure 3.

30
L

>>a•—I

en

CO

(U00un

COoOOO

Oh

ni

U-J(0a

Oho-IOh o

COud

bo

31
3. 4. 3 Output

The output of this computation is a graph of peak svirge pressure

as a function of pump start-up time. A typical example is shown in

figure 14. As the pump start-up time (time to bring the pump from

rest to operating speed) is shortened, the amplitude of the peaks

increases until a maximum is reached at the critical value of the

start-up time. Further decrease in the start-up time has no effect

on the peak amplitude. The maximum pressure and corresponding

critical pump start-up time are indicated in the output graph.

32
33
4. Computation Options, Post-Cooldown Period

4. 1 Option 5 - Water Hammer - pressure spikes due to water

hammer when valves are closed in a flowing liquid stream.

4. 1, 1 Application

This computation applies to the case in which a downstream valve

is closed against a flowing liquid stream. Deceleration of the liquid

due to impingement in the closing valve can lead to a sudden large

pressure spike. The amplitude of the pressure spike is a function of

the valve closing time. Details of the computation and computer

listing are given in Supplement A (1974).

4. 1. 2 Input Data Entries

Section 2. 3 describes the general log-in procedure by which the

Option 5 is selected. After this selection has been made, a displaysimilar to figures 15 and 16 will appear in sequence. In the display,

if desired, the input variables may be examined and changed by the

procedure explained in Section 2. 4.

34
O.J

CO

_}

•a: !—;

0"! cos:

ll z: I-' cti

i-_j:z:

CO <r

UJ

COo

_jo 1 1 1 , ...^ 04

"7" Cn

!—i

"7" 0. CO

1—1

i—«

UJ . ^: C3 HI

CD CD z

yj !—i

CO' ill CO CO 0

CO _J

UJ :• 1—( 0

r--i Ui

!—i

•w-i

N

Q |J Ui

CO CO i—i

UI ui

S—1

CO CO . >—i

CO 0

IZI 1—1

CO 0 u_ LU 0 -J Ui M UJ 1—i

ZI _i CJi 5X1

h-i r-.j <I 0

CO o i-A .-• h- Ul.X' UJ 1—i

CO 0 CO z © ; i- •—«

ZI 1- _J

!—i

CJ'

"7" 1- UJ ce: <I

^! CJ« —s

UJ <xj z> ^

i_J HI :z

Q ^

i- CO Ui UJ

i—t

a: o UJ UJ x>

X

H- >—i

Li: UJ Ui h-_J i—

C_' UJ . i

—>

Ui

—i

si: a: Ui -J CO i-- U.

LiJ ~r <r UiUJ

UJ u_ l_i V- I—1

_:• O-J

Q: ill UJ u_ _J !_! ii. m Q: •:I UI .;-r LU U_ Q: UiC ui

in Ui CO >_j 0 L3 0 ii;

iTi UJ CO U- •:X h- ui UJ >— UJ I Ui y- CO co UJ u_ j— U3 XUi 0. CD 'v' i-H Uico ID O

"7" UJ

_i .—i

UJ ;

iX _i LU

"T" :X

X -J i UJCj i

i-1 j

iX ii-

—

a:: t t

Cfci ' I i -J UJ

—

®

f— Zi i iZ Zi ZQ Ui

.•T '.-r I—: .J ZI >-• ii." — z: Li_ IZ ilL i •

f-"i co I—I a

..—I

0)a

j:3u

LT)o

Oh O

in

(Ud

CXI • t-i

35
36
4. 1. 3 Output

Typical graphs of the amplitude of water hammer pressure spikes

as a function of the valve closing time is shown in figure 17,

37
38
4. 2 Option 6 - Cold Flow. Steady flow operation and transient

response to changes in operating conditions.

4. 2. 1 Application

This computation applies after the transfer line has reached

operating temperature. It deals with response to changes in operating

conditions but does not deal with cooldown transients. The latter are

treated separately in Section 3. The flow rate and liquid discharge

temperature (or two phase quality) are calculated as functions of the

pump speed, ambient air conditions, valve settings, and pipe geometry.

The accumulated liquid, change in supply liquid level, and pump discharg

pressure are also computed. Pump speed and valve settings are allowed

to vary with time. Details of the computation and computer program

listing are given in Supplement A (1974).

4. 2. 2 Input Data Entries

Section 2. 3 describes the general log-in procedure for the graphic

display system. After the Option 5 is selected, a display similar to

figure 18 and 19 will appear. If desired, input variables may be examine

and changed in the display by the procedure explained in Section 2. 4

except in the table of numbers showing time, valve opening, and pump

speedj where the vertical and horizontal cursors must be positioned

before depressing the space bar.

Entry 1 allows a supply ullage pressure during transfer to be

selected which may or may not be different from the ullage pressure

during storage. (The storage pressure is taken as that pressure which

was selected previously under General Input Data. ) Entry 1 along with

entry 2 relates to the subcooling of the inlet liquid. This subcooling

enters into the calculation of discharge liquid temperature, or fraction

of vapor being discharged. Entry 4 allows for the selection of a schedule

39
of changes in operating conditions. That is, the pump RPM or the

discharge valve setting may be specified at six times. RPM and

valve setting change linearly from one specified time to the next.

The program carries out the computation to ten seconds beyond the

last entry in the schedule.

The third entry under Cold Flow allows the selection of compute

quantities to be displayed. The desired quantities are selected as numbers 1 through 6. Striking ALT MODE initiates the calculation,

and the next display is the selected output graph.

40
to GOoo

>-I GO

oe: CD O O

O CD

Q_ un CD CD

S: i-H LH Ln CD CD

(_/ 

LU

—

1 i ill • U 1 III (—

1 ff

\y

J 1 1 us 1 1 1 1 1 Wj 1 1 1 »—\ 1 1 ft< LX. 11 1 1 1 1 1 1 1 i LU _^ f n % / 1 i 1 1 1 

III r>1 i 1UJ1 1 Q_ - •>> ill LU \^ y

ft 1 1 i ' ' ' 1 I 1 » 1 1 1 

111 iiU /

\ V / f o i • 1 5- • 1 1 1 1 ' ' ' 11 V / ^|*» COill 11 L_1 1r 11 1 1 

UJ III UJ 1 1 ViiJ 1 

1 1 / >

Vi 1^ 1 ft 1 1 UJ 1 1 

III 11 5- ryLX.

N t 1 i 1 1 ft1^ V J 1 1 1 11 1 1 1 1 -1— ry I 1 1 k V ^ llj III #w« 1UJ1 ] 1ill1 1 V ^ 1 1 1 V—/

III -J— WJ CO >>> ^ 1I 1 1 

UJ rv L_ 1 11 1 #v . u 1 1 

III 11 1 1 tf\ \Ss / 5-2. ry1 

1 1 1r 1 1UJi 1 LU III UJ —

la^» 1 1 if\ VJ ll 1 11 1 

X 1^ 1 1 i ' ' ' 1L^J1 1 1 1 1 ' ' ' # o 1 1 1 1 1 

UU 1 i 1 < in V J 1 r |wK 1 1 III LXJ LL y.—^ AD— 1—

U- ill 1 It (—

LiJ- IX. 1 1 1 Li_l ill UJ ill LU

—

0 Ll- 1 1 UJ Ill UJ %jj 2.V" 1 1 1 (—

1LUI 1 1 U- Q ill LU

J ex. LU < 1r~ 1 1 1 1 —*-> cV n/ -T- ry LU 1 1 

LjIIIJ /—\ i 1 OO o < CO Q. X > LU tD 1

rD OO LU h- q: 0 CO < CD oo LU CQ co C/5 LU > cr <a: 1— CO OH *^ q: Q CD LU h- < or LU Q. _l LU o: CC X C_)

a: 1 < < > Q < 3 _J CJ Q- LU 0 3 X CO < CO U- Q Q Od LU G> 0 CO 3 0 CO

LU LU UJ U_ CO LUa

a LU

CD 3 f=) < cr LU 1— o 3

_J < < a:Q H- 1 =3

ZD 1— LU X5

__l C3 =) < Q. LU _J 3 C3

113 >- 1- 1- D- 0 1- z: z Ha LU 1 1 < < 1— 0 3 3

LU >- Q- </> CO ZD h- o_ _l 0 _i C_) "\ Q- 1 O- h— 00 LU O Q- LU 1 1 1 1 1 1 1 O- OO 1 LU LU >- =3 .-H IE CSI LTk UD

OO h- 1— ^

UJ\—

CO i-H

OO CDOO CD

LO

O

O Ln LA LO

C=) CD

CD <Z>

O

OO

O Ci3 CD «—

to •—•__I0»-Hr-H<3 0CD -L^do

I—

«+HOoI co• f-l ft o

00I—

u

(20

41
42
4. 2. 3 Output

Typical output graphs are shown in Figures 20 through 25. The

following variables may be plotted as functions of time:

Fig. 20. Flow rate

Fig. 21. Total accumulated liquid discharged into the receiver

after subtracting off the quantity vaporized

Fig. 22. Pump discharge pressure

Fig. 24.

Fig. 23. The line pressure ahead of the discharge valve

Final vapor fraction

Fig. 25. Fluid discharge temperature .

43
\

\

CM

o <r

a: u. H-QO

a: -J -J z:uj OQ<r

<E-j<r

CO + 1 UJ liJUJ iM

t-« 00 «-i ••-« u II 11 >>

•-i © + + +

UJUJ UJ ID©

00©

CO

tl li li X X

,©

uJ

C'.J

j-i-io:

CO-JX

o

ll. ...J czris. ct; 1- UJ u a. s:

o

do

• r-l a, O

o

(M

0)d

CUD

44
T3

(U

G

O

u

3

a,O

o

a, O

0)d

CuO

^- Q K o: _j LJ v-1 CO O X O: Lt L3 UJ Q L3 >I _J

45
(L) d• i-l oudoOO

00

fM

Q)U

ISCUD

46
47
48
OO •—

on: LU

z: o

LU Ll_

I—I LU

OO OQ

<r QLU

oo

o

to

Q_ Z LU O 1=3 >-

<i: -J

oc: Q_

LU Q_

O OO >- Q C=> —

<C Z3

LU C3

h-

^

OO _J

9

o

OO

CD

CDO

CM

CD O O

OO

CD

Ho '3dniVy3dW3i 39yVH3Sia

49
5. General References

Brentari, E, G. , Giarratano, P. J. , and Smith, R. V. , Boiling

Heat Transfer for Oxygen, Nitrogen, Hydrogen, and Helium,

Nat. Bur. Stand. (U.S.), Tech. Note 317 (September 1965).

Holten, D. C. , A study of heat and mass transfer to uninsulated

liquid oxygen containers. Book, Advances in Cryogenic

Engineering 6^, Ed. K. D. Timmerhaus, pp. 499-508

(Plenum Press, New York, N. Y. , 1961).

Lange, N. A. , and Forker, G. M. , Handbook of Chemistry, Tenth

Edition (McGraw-Hill Book Company, Inc. , New York,

Toronto, London, 1961).

McAdams, W. H. , Heat Transmission, Second Edition (McGrawHill Book Company, Inc. , New York, Toronto, London, 1942).

Novak, J. K. , Cooldown flow rate limits imposed by thermal

stresses in liquid hydrogen or nitrogen pipelines. Book,

Advances in Cryogenic Engineering J_5^, Ed. K. D. Timmerhaus,

pp. 346-353 (Plenum Press, New York, N. Y. , 1970).

Rich, G. R. , Hydraulic Transients, Second Edition, pp. 1-73

(Dover Publications, Inc. , New York, N. Y. , 1961).

Richards, R. J. , Edmonds, K. , and Jacobs, R. B. , Heat Transfer

Between A Cryo-Surface and a Controlled Atmosphere,

International Institute of Refrigeration, Commissions 2,3,4,

6a, Washington, D. C. (1962).

Rohsenow, W. M. , and Choi, H. , Heat Mass and Momentum Transfer

(Prentice -Hall, Inc. , Englewood Cliffs, New Jersey, 1961).

Ruccia, F. E. , and Mohr, C. M. , Atmospheric heat transfer to

vertical tanks filled with liquid oxygen. Book, Advances in

Cryogenic Engineering 4, Ed. K. D, Timmerhaus, pp. 307-318

(Plenum Press, New York, N. Y. , I960).

50
5. General References (Continued)

Salisbury, K. J. , Kent's Mechanical Engineers Handbook, pp. 5-17,

18 (John Wiley and Sons, Inc. , New York, N. Y. , 1950).

Steward, W. G. , Transfer line surge. Book, Advances in Cryogenic

Engineering J^, Ed. K. D. Timmerhaus, pp. 313-322,

(Plenum Press, New York, N. Y. , 1965).

Steward, W. G. , Smith, R. V. , and Brennaji, J. A. , Cooldown time

for simple cryogenic pipelines. Developments in Mechanics,

Proc. of the 10th Midwestern Mechcinics Conference, pp. 1513-

1525 (Johnson Publishing Company, Boulder, Colorado, 1968).

Steward, W. G. , Transient Flow of Cryogenic Fluids, Ph. D. Dissertation, Colorado State University (1968).

Voth, R. O. , Cooldown pressure surges (Part II of unpublished NBS

Report: Ludtke, P. R. , and Voth, R. O. , A Study of LC-39

Cryogenic Systems - Final Report, 1971).

5. 1. System Reference Manuals*

General Electric, DATANET-760, Programmers Reference Manual,

General Electric Information Systems Division (1967).

General Electric, DATANET-760, Keyboard/Display Subsystem

Manual, General Electric Information Systems Division (1969).

Honeywell, GECOS III, Time -Sharing Fortran, Honeywell Information

Systems Inc. , Doc. No. CPB-1566B (1971).

Honeywell, GECOS III, Time-Sharing General Information Manual,

Honeywell Information Systems Inc. , Doc. No. CPB-1643A

(1971).

Supplement A, Oxygen Loading Simulation Computer Programs

(1974). Available on request.

Identification of a manufacturer and a manufacturer's product has

been necessary to make the results of this work meaningful and in no

way implies a recommendation or endorsement by the National Bureau

of Standards. 51
Appendix A. Heat-Mass Transfer Correlations for Uninsulated

LiOX Transfer Lines

Expressions for heat flux from the atmosphere to uninsulated

LOX lines are needed for estimations of fluid enthalpy rise along the

line. This enthalpy rise in turn determines whether the fluid being

discharged is subcooled or is saturated and partly vaporized. A second

application is in the computation of cooldovm time. During cooldown

the heat from the atmosphere adds to the vaporization rate due to cooling of the pipe walls and thus lengthens the cooldown time.

After the pipeline has cooled down to a stable operating temperature, the resistance to heat transfer is primarily in the outside film -

that is, between the pipe wall and the ambient air. The heat flux then

depends on the ambient air conditions and the build-up of frost on the

2 2

transfer line. A minimum heat flux of about 0. 076 W/cm (240 BTU/hr ft )

is expected in still dry air after the maximum thickness of insulating frost

is established. Heat flux under the worst conditions should be less

2 2

than 0. 95 W/cm (3000 BTU/hr ft ). These values lie within the nucleate

boiling range for liquid oxygen (Brentari, et al. [1965]) therefore, film boilir

with its large wall-to-LOX temperature differences, should not be

necessary to consider.

The heat flux after steady state is reached depends on the frost

thickness and surface temperature. These factors are at least partially

self- regulating in that the frost tends to build up to a stable thickness then

begin to slough off. A frost surface temperature drop causes additional

frost thickness to build up, increases the insulating effect, and thus

re-establishes the higher frost surface temperature. This regulation

is imperfect, however, ajid determination of this frost surface temperature is probably the most questionable factor in the heat flux prediction. The value of frost surface temperature calculated by Holten [1961]

52
and measured by Richards et al. [1962] for liquid nitrogen cooled

surfaces corrected for the higher temperature of LOX -- was

used in the present calculations and appears to give reasonable predictions judging by comparisons with the liquid nitrogen data of

Richards et al. as well as Ruccia and Mohr's [I960] LOX data. Our

method over-predicts Holten's LOX data by 20 to 30%; however, the

heat flux in those experiments may have been reduced from the freeair values by the partially sheltered placement of the test vessels.

Holten's correlation fits his own data but underpredicts the other data.

Heat flux occurring after cooldown, but before the frost has

established a stable thickness, is considerably higher than the steady

state values. This initial heat flux is predicted satisfactorily by

assuming the surface temperature equal to the liquid saturation temperature. An empirical curve fitting was used to obtain the variation

of heat flux with time between the initial and steady state values.

Our developments of the correlations and comparisons with

data are summarized in the following sections.

Al. Mass Diffusion Heat Flux

In heat transfer to surfaces at cryogenic temperatures condensation of water vapor (or air) can along with convection and radiation, comprise a significant part of the total heat flux. Where condensation is present with forced convection, it is assumed that the

convective effect is not altered by the mass trajisfer and the heat

fluxes resulting from the two effects may be added. Radiation is the

third component to be added.

The heat transfer effect of mass diffusion is due to the giving

up of sensible heat and latent heats of vaporization and fusion by

the water at the condensing surface. The mass diffusion heat flux is

53
(Q/A) -w(I -I) (Al)

ail a 1

w = rate of condensation per unit area

= enthalpy of the water vapor in the ambient air

I. = enthalpy of the water in the condensed state

1 .

I -I. 2= 2990 J/g (1287 BTU/lb).

a 1

In terms of the diffusion coefficient

(P P . \ P

wa wi I , wa , ^ . . a 1 / a

h... = mass diffusion coefficient

dif

P = partial pressure of water vapor in ambient air

wa

P . = particil pressure of water vapor at the condensing wi . surface

R = gas constant

T = temperature

(P,R,T in consistent units)

H = specific humidity

p = density of ambient air (due to the approximate

nature of this calculation a standard value of

0.0012 g/cm^ (0.075 Ib/ft^) was assumed).

The mass transfer of water vapor is treated through an

empirical analogy between heat and mass transfer. The ChiltonColburn cinalogy (Rohsenow and Choi [196l])gives

a pa

2/3

dif p C

a p a

(A3)

54
where C = specific heat of air at constant pressure

pa

Pr = Prandtl number for air, C m-ZK

P

= viscosity

K = thermal conductivity

Sc = Schmidt number = p-/ pD

D = mass diffusivity

V = velocity.

From Al , A2, A3

If it were not for mechanical failure of the frost, one woiold

expect the outer surface to reach approximately 273 K (32° F); however,

the frost surface continually sloughs off, exposing a colder layer.

Therefore, as the water vapor diffuses toward the cold surface, it

encounters a temperature at which it condenses before it actually

reaches the surface, and much of the condensate falls or is swept

away without attaching itself to the surface. Then some of the heat

given up by the water vapor is indirectly transmitted to the pipe surface

through the air convection currents.

Holten [I96I] calculated from his heat transfer data a steady

state LiOX container frost surface temperature, T^, of about 210 K

(- 80° F). Exactly the same figure can be derived from the frost surface

temperature of 204 K measured by Richards, et al. (1962) for a liquid

nitrogen test section if one assumes that the fractional temperature

drop across the frost layer is the same for LOX as for LN^ . That is;

AT /AT = AT /AT

frost, LOX over -all, LOX frost, LN^ over-all, LN^

(T^ - 90)/(300 - 90) = (204 - 76)/(300 - 76)

T^ = 210 K.

The average film temperature is (210 + 300) /2 = 255 K (0°F).

55
The following properties are evaluated at 25 5 K (Rohsenow and

Choi [ 1961]),

for air Pr = 0.722 and C = 1 . 0 J/(g • K) (or 0 . 239 tTT^) Pa ID £

for water Sc = 0.6.

Substitution of these constant values gives

/ W \ 3 W

Q/A^.J - \ = 3.38 (10) hH (h [=] , H [=]

\cm / cm K g (air)

or

(Q/AK./^^") = 0.868 hH(h[=]^TU^ H[=]^i^). (A5)

, ''"Vhr ft / hr-ft "F

'

A2. Convection Heat Flux

A2. 1 Natural Convection (still air)

McAdams [1942] gives the following expression for natural

convection across single horizontal tubes,

^""Nu=h^ - 0.47 [Gr Pr]°' (A6)

I Or is the Grashof number evaluated at the film temperature

„ Gr -(^) at

• '• where 0 = thermal coefficient of volume expansion . The group in parenthesis is given by Rohsenow and Choi

. for air at 0 °F.

4^ = 267

^

/or 4.2,10)^ V

^ cm K \ ft °F /

56
From the same source

Pr =0.722

-4 W BTU K =2.25(10) ,0.0.013;^^:^).

Substitution of the constant values into (A6) yields

(*).

1 25 W , „ . . .-4 AT • -= h AT = 3.94(10) —^ (AT [=] K, D[=] cm) (A7) „0.25

c cm D

or

1.25

(t) — \^/c hrft

f-

= 0. 255^^^ (AT [ = ] °F, D[ = ]ft).

From (A5) we get

/Q \ W /AT \ ^'^^

N 'dif cm \ /

AT [ = ] K, D [=] cm, H [=]

H

(A8)

or

/^\ _BTV__

V^/dif hrft^ V° /

AT[ = ] °F. D[ = ]ft, H[=]S£^= .

A2. 2 Transition Velocity - Natural Convection to Forced

Convection

The transition velocity is obtained by equating Nusselt number

for natural convection to Nusselt number for forced convection. For

forced convection in the Reynolds number range 1,000 to 50,000

57
Nu = 0. 26 Re°'^ Pr°* ^ (Mc Adams [ 1942]) (A9)

By equating (A6) and (A9) we get

0. 25 n 1/0.6

Re = ro.47 0. 25 Pi_ll

[0.26 p^O.3 J

Substitution of the constant values listed previously gives

y(^-f^) =3.18 D°-25 ^T°-'*1^D[ = ] cm, AT[ = ]K)

or

{&) = 690 D°*^^ AT^*'*^'^ (D [=] ft, AT [ = ] °F).

For D = 30.5 cm (1 ft) and AT = 90 K (162 F)

cm V ^ 49 orl.76Km/hr or 1. 1 mi/hr.

s

Therefore, if the wind velocity is less thein approximately

1 mi/hr, the natural convection expression will be used. If V is

greater thcin 1 mi/hr, one of the following forced convection expressions will be used.

A2.3 Forced Convection

Equation (A9) fits experimental data given by McAdams up to

5 Re —10 . This corresponds to a wind velocity of about 12. 1 Km/hr

(7.5 mi/hr). Equation (A9) diverges rapidly from the experimental

5 data above Re = 10 so that at 24. 1 Km/hr (15 mi/hr) (A9) underpre5 diets the data by 40%. For Re > 10 (V > 7. 5 mi/hr) we have developed

the following equation, assuming the same Pr dependence:

58
Nu= 0.00332 Re^-^^^Pr^-^ (AlO)

A2. 3 . 1 Heat Flux for 1 . 76 < V < 12.1 Km/hr

(1 < V < 7. 5 mi/hr).

From (A9) we get

Substitution of the constant values yields

(W \ -4 V^*^ cm 2—j = 1.75 (10) ^ D[.] cm) (All) ^0.4 ^ ^ ^ s

or

.0.6 (BTU \ V =

) = 0.608 -rr-r (V [ = ] ft/s, D [ = ] ft),

hrft "F/ d"-^

From (All)

.0.6

(a~) ^1" = ^-^^^ (lO)-"* AT (V[ = ]^. D[ = ] cm

" ^ * AT[ = ]K)

or

.0.6 /Q^\ BTl

^^/c hrft

= 0.666 AT (V[=] ft/s, D [=] ft, AT = ° F) (A12)

D

•

From (A5) and (All)

.0.6

(Q \ W V cm e X) T — 590-Q-j H (V [ = ] —, AT{=]K, H[=:]^ ,D[=]cm) (A13)

' dif cm D * 8

or

(x) ^4 ^ (V [=]ft/s, AT [ = rF. H [=]

Mif hr ft^ d"-^

D[=] ft) .

59
A2.3,2 Heat Flux for V > 7. 5 mi /hr

From (AlO) we get

^0.982

0.00332 ^f^V^ (Pr)°•^ D \ ^

Substitution of the constant values gives

.982

.( T—)=4,75 (10) —

\cm K / D

(V[3]H£L, D[ =

] qm)

.018 ' s

%r ft K / D

Due to the small exponent of D, ajid the value of D being on the order

of 30. 5 cm (1 ft),

0.018

\30.5 J

^1.0. Then,

h(—^) = 4.72 (10)-^ V°-^^' (V [-] ^) (A14)

\cm K /

^

or

4.72 (10)"^ yO,98Z ^rj,^

c From (A5) and (A14)

-^;- = 0.123V°-982^j^ cm ^ ^^^^^

j-r ^ S g

dif cm

\^/dif hr ft'^ ^

^

60
A3. Radiant Heat Flux

The heat flux due to radiation from the ground cind sky is

Q 4 4

For diffuse radiation from a distant enclosure the emissivity factor

F may be taken as the emissivity of the frost surface. Holten [1961]

and others assign values of about 0.9 to this factor. The Stefan -Boltzman

constant a is

-12 W

a =5.67 (10)

cm K

or

0. 174 (10)"^ BTU/hr ft^°R^.

T, = 210 K (378 °R) as before. Substitution of these values give frost

Q/ W\ -124 4

X ( 2)= 5- 1 (1°) (^a " ^ f \ cm /

Q / BTU \ j^4 ^^4 _ ^^g4^ ^^^^ ^\hrft^°F/ ^

In open sunlight the mean heat flux to an essentially black sur- face is approximately

= 0.068 Wcm^

P

= 215 BTU/hr ft^,

P

assuming an atmospheric transmittance of 0.5. is the projected

area (seen by the sun). In terms of the pipe surface area A:

61
A ttDL

P

Therefore

Q 0.068 . 2 ,^ ^ BTU = 0.0216 W/cm or 68.4-

hr ft

To avoid unnecessary complication, we assume 50% sunlight. Then

the total radiant heat flux is

(*1

W .12 4 4

= 5.1(10) (T - 210 )+ 0.0216 (T [ = ] K) (Al6)

rad cm

/Q_\ BTI

/ rad hr ft

^"^^

= 0.154 (10)"® (t"^ - 378^)+ 34.2 (T [ = ]R).

a a

A4. Conversion of Relative Humidity to Specific Humidity

Specific humidity H may be expressed in terms of the total

(barometric) pressure B eind the vapor pressure P as

1 8 ^2^

H =

or

1.61(^-1)

V

_ 7000 grains

^1.61,^-1)

V

The vapor pressure corresponding to the dry bulb temperature

T °F is, by the Antoine equation (Lange [1961])

a

= exp ^18. 67 - lll'^;^ ) mm Hg . (A17)

62
V

From the definition of relative humidity, H

P =H P,.

V r d

Then,

H = 1.61 (B/H Pj - 1) r d

An average value of B = 760 mm Hg yields

or

H = 1224

r d

1.61 g

(A18)

H = 7000

1224

r d

1.61

grains

lb

(P^ from eq (A17)).

A5. Comparisons With Experimental Data

Calculations of heat flux to uninsulated liquid and liquid oxygen

transfer lines and vessels are compared with experimented, data from

the following sources:

Author

Richards et al

(1962)

Ruccia, Mohr

(I960)

Holten

(1961)

Fluid Apparatus

LN^ Horizontal cylindrical test section 5.08 cm

OD X 15.2 cm long (2 in OD x 6 in long) in a wind tunnel. Controlled velocity and humidity.

LOX Vertical cylindrical tank 45. 7 cm OD x 6.71 m

(18 in OD X 22 ft) high. Engine driven propeller

provided wind. Humidity not controlled but

measured.

LOX Spherical tanks 13. 7 cm OD ( 5-3/8 in).

Natural convection.

63
A5. 1 Comparison with Data of Richards et al. [1962]

Since liquid nitrogen was used in these experiments the value

of was 204 K (368°R) and AT was 95.6 K (172 "F) (Sec Al). The

average frost thickness was approximately 0,952 cm (3/8 in), so that

effectively 1.91 cm (3/4 in), or 1.91 cm (0.0625 ft) is added to the

outside diameter. That is, D = 5.08 + 1.91 = 6.99 cm. Equation

(A12) becomes

(Q/A) = 0.00770 V°*^ (V [ = ] cm/s) (A19)

c c cm

or ' (Q/A) = 206.6 V°-^ (V[=] ft/s).

hr ft

Equation (A13) becomes

W 6

(Q/A)^.^ 2-3. 272 V H (V [=] cm/s, H [=] g/g) (A20)

cm

or

(Q/A)^.^ = 1.042 V°-^ H (V [ = ] ft/s, H [ = ] grains /lb).

And the heat flux due to radiation without sunlight is, from (A16)

(Q/A) J = 0.0328 W/cm^ or 104 BTU/hr ft^.

rad

The calculated heat flux for the experimental conditions are

summarized in the following table.

The comparison between these calculated heat fluxes and experimental data of Richards et eil. [1962] may be seen in Figure Al.

64
1

o

a

o o a- o CM 00 o 00 o 1—

fO

CO vO 5 1—4 CO

o

E-i

d

jS o

to a

.2

Pio

o

01

4->(«y

U

g

5

a

5

X

00

t3fl

ID 00 1—

rg ID

1—

(

00

i-H tn I-H rH hI—

f-H

fVj in vO 00 CO ID vO 00 00 1—

vO o 00 1—1 o

o ID o CJ ID o o o o o o o o

vD 00 I-H CM CO o o o o o I-H ID 00

• • • •

00 00 00 00 00 00 00 00

(M (M OJ M CM ro

CO CO CO CO CO CO CO CO O o o o o O o o

o o o o o O o o

o O o o o o o o o o o o

OJ CM

vO vO vD sD

00 00 00 00 o o o o (M CO o o o o

• •

I-H ID ID ID I-H KD ID ID

ID ID

CO CO

CO CO r~

I-H o 1—

o

CO 00 CO 00

ID CO ID CO TfcvjcNivo-^rorOso

CM r-4 T}^ (VJ I-H TjH

I-H CM I-H CM
66
A5. 2 Comparison with the Data of Ruccia and Mohr [I960]

Ruccia and Mohr present data for natural convection, and

5.33 m/s (10 knot) and 12.6 m/s (24.4 knot) wind velocities.

For natural convection over verticcil flat plates McAdams [1942]

recommends the following form of correlation (assumed applicable to

vertical cylinders):

b Nu = a(Gr Pr) .

For L = 6.71 m (22 ft) and AT = 90 K (162°F), and the properties of

1 2

air of sec A2. 1 we get Gr Pr = 5. 22 (10) , which is beyond the range

of the equation given by McAdams. We have fit the data given by

McAdams at high Gr Pr by the following equation

Nu = 0.0325 (Gr Pr)^*^^^ (A21)

from which we obtain

(Q/A) = K/L Nu AT = 0. 0751 W/cm^ (238 BTU/hr ft^) c and from (A5)

(Q/A)^.^ = K/L Nu 3.38 (10)^ H = 2.82 H W/cm^ (H [ = ] g/g)

or

(Q/A)^.^ = 1. 275 H BTU/hr ft^ (H [ = ] grains (lb),

ail

In Ruccia' s and Mohr's experiments the humidity varied from

0.006 g/g (42 grains/lb) to 0.014 g/g (98 grains /lb).

The forced convection Reynolds numbers corresponding to the

5 5 10 and 24 knot points are respectively 1.98 (10) and 4.83 (10) . These fall within the range of equations (A14) and (A15). From these

equations

67
2 0 Q8 2

(Q/A) BTU/hr ft =42.4V (V[ = ]ft/s) (A22)

or

2 n Q8?

{Q/A)_3,, BTU/hr ft = 0.2272 V

'^^ H (V[ = ]ft/s,

'dif

H [ = ] grains/lb). (A23)

The radiation heat flux is, from (Al6), assuming T = 540°R

J

= 101 BTU/hr ft' Rad

2 4 0 Q82 (Q/A)^W/cm = 4. 25 (10) V (V[ = ]cm/s)

(Q/A)^.^ W/cm^ = 0. 123 v^*"^^^ H (V [ = ] cm/s, H = g/g).

The calculations are summarized in Table A2 and compared with

the experimental data in Figure A2.

Table A2

V V H H

cm/s ft/s g/g grains/lb

Natural Convection

(Q/A)^ (Q/A),if (Q/A)j,^, (Q/A|^^^^ ,Q/A)^^^^

BTU/hr ft W/cm

- 0. 006 42 0. 0751 . 0170 0. 0318 0. 124 393

- 0. 014 98 0. 0751 . 0394 0. 146 464

Forced Convection

533 17. 5 0. 006 42 0. 223 . 0501 0. 305 967

1260 41. 2 0. 006 42 0. 515 . 116 0. 663 2101

533 17. 5 0. 014 98 0. 223 . 117 0. 372 1179

1260 41. 2 0. 014 98 0. 515 . 270 0. 817 2591

68
I.O

0.75

M

E

o

X* 0.50

I-

<

UJ

0.25

WIND VELOCITY, ft/t

10 20 30 40 90

1 1 1

1

H » 0.014 g/g

^f8 grains \

V lb

1 y

1 l_

H • 0.00€

/42 grail

I lb )^

U

/^^Calcu lationt

•Notui*q\ convecti on

x:

"s. 2000 3

X

3

<

1000 X

400 800 1200

WIND VELOCITY, cm/8

1600

Figure A2. Comparison of calculated steady state heat flux with the

experimental data of Ruccia and Mohr [I960] for a liquid oxygen cooled

vertical cylinder 45. 7 cm (18 in) OD x 6. 71 m (22 ft) long.

69
A5 . 5 Comparison with Data of Holten [1961]

For natural convection heat transfer to spheres Bird et al. [1964]

recommends

Nu = 2 + 0.6 (Gr)^^^ (Pr)^^^ . {A24)

The constants are

D =13.6 cm + 0,6 cm (approximate frost thickness x 2) = 14. 2 cm (or 0. 469 ft).

AT = 90 K (or 162° F).

(Other constants from Sec. A2. 1).

From (A24) and the constants,

h = 8. 16 (10)"^W/cm^.K(or 1.44 BTU/hr.ft^. °F) (A25)

(Q/A) = 0.0735 W/cm^(or 233 BTU/hr.ft\

c From (A25) and (A5),

(Q/A)^.^ W/cm^ = 3.38 (10)^ hH = 2. 75 H (H [ = ] g/g)

all

or

(Q/A)^.^ BTU/hr.ft^ = 1. 25 H (H [ = ] grains /lb).

The radiant heat flux is, from Sec A5. 2

(Q/A)_ , = 0.0319 W/cm^or 101 BTU/hr.ft\

70
Calculated steady state heat flux compared to the experimental values

are as follows:

H H

(Q/A)Exp 'Calc '°/^'calc

g/g grains /lb -BTU/hr ft W/cm

0.0065 45. 5 3 25 391 0. 102 0. 123

0.0070 49 315 395 0.099 0. 125

0.0074 52 330 399 0. 104 0. 126

0.0076 53 340 400 0. 107 0. 126

0.0097 68 336 419 0. 106 0. 132

0.0120 84 345 439 0. 109 0. 138

It is apparent that the ccilculated heat flux is 20 to 30% higher

than the experimental data. A possible explanation is that the heat

flux in Holten's apparatus was impeded to some degree by the sheltered

placement of the spherical vessels.

Since this over-prediction is not apparent in the other comparisons we assume that the predictive method is satisfactory.

71
Appendix B. Cooldown Surge

Bl. Introduction

Large amplitude pressure surges are often observed when a

cryogenic liquid is forced into a warm transfer line. While water

hammer pulses (sec. 4. 2) are associated with the impingement of

liquid on a closing valve or other restrictions, these cooldown surges

are associated with the opening of an inlet valve or the starting of a pump. Cooldown surges have been analyzed by means of computer

solutions of the unsteady two phase flow equations (Steward et al. [1968]),

the result of which being a stepwise calculation of all the variables in

time and space coordinates. Not only are such detailed calculations

too lengthy for this system analysis, but they produce unneeded information. In the present case only the peak amplitude which results

from a particular mode of operation is required; therefore, a correlation of peak surge pressure as a function of the operating conditions

is desirable. The following sections describe the development of the

correlation used in the present system analysis and show some of the

results in comparison with previous experimental data.

The usual dimensional analysis approach to the development of

an empirical correlation assumes that a proportionality exists between

powers of dimensionles s groups of parameters. It does not normally

allow for the possibility of additive terms or other functional relationships such as trigonometric, exponential, etc. In the present approach

both the dimensionless grouping of parameters and the forms of the

relationships are derived from a model of the process. It should be

understood that the derivations are not rigorous and leave empirical

coefficients to be established from the experimental data.

72
During cooldown of pipelines with length to diameter ratios of

450 and greater, observed stream and wall temperatures followed a "cold front" pattern. That is, at a given time temperatures upstream

from a moving cold front were near the liquid saturation point; downstream from that point the temperatures rose sharply to near the

initial temperature. The limiting extreme, in which the temperature

distribution in the line is reduced to one moving temperature step,

from liquid to ambient temperature has been used with good results as a basis for cooldown time and pressure surge analyses (Steward

[1965] [1968]) and will be used here.

B2. Derivation

As liquid flows into the warm part of the pipe and, after a time

delay, becomes saturated, vapor begins to form in the liquid stream.

The vapor carries liquid with it as it moves downstream and thus

further increases the heat transfer surface area. As the rate of vapor

formation increases, the pressure in the liquid-vapor trajisition region

(or at the assumed liquid warm gas interface) rises due to the resistance

to the flow of gas. Experimental data show that the measured pressure

is in phase with the gas velocity. Thus, the surge process is unlike a

frictionless spring -mass oscillating system in which the spring force

is 90° out of phase with the velocity. Therefore, we conclude that

the inertial effects (time derivitives of velocity) are small compared

to the frictional effects. This conclusion is supported by detailed

computations using the complete momentum, energy, and mass conservation equations (Steward et al. [1968]) in which the magnitude of

individual terms can be examined. Experimental measurements and

computations show that the peak pressure occurs approximately at

73
the interface between liquid and vapor. The compressible gas in the

warm part of the pipe expands and accelerates in the direction of

flow to a maximum velocity at the discharge. The discharge velocity

may be subsonic or sonic; however, for high peak pressure conditions

which would be of concern, the discharge velocity would be sonic. For

example in Fanno flow with f L /D (friction factor times gas length

to diameter ratio) greater than 15 a ratio of peak pressure to discharge

pressure, P /P, greater than 5.5 would produce sonic (choked)

p d

discharge

For choked Fanno flow (constant area ideal gas flow with

friction, without heat transfer) Shapiro [1953] gives

fLj . i-M.^ y->/

)yj irn) M.^

where M^is the upstream Mach number and Y is the ratio of specific

heats. For the purpose of correlation the logarithm term may be

eliminated with no more than 20% loss of accuracy. Then,

K ^

A s.e , ^

(Bl)

J D

1 1-1

The mass flow rate corresponding to is

w = M p AV where A is pipe area . (B2)

1 g s

Substitution of ideal gas relations for density p and speed of sound V , g

^ and equation (Bl) for M^yields,

74
"3 ^ / K ^ ' (B3)

D

where R is the gas constant, is gas temperature, and

P is the peak pressure.

P • The total gas flow rate w may be expressed as the sum of aji

equilibrium flow rate w , and an excess vapor formation rate w

eq ^ ex

w = w + w . (B4)

eq ex

The equilibrium flow rate w is that which would exist in a

eq

steady cooldown without surging. In such a steady cooldown process

most of the pressure drop - P^ (Pj is the upstream pressure) appears

across the gas stream until the liquid front very nearly reaches the discharge

end, i. e. , until cooldown is nearly complete. Then, for

^

P, A

W_ r — l/-r^ (B5)

From (B2),

' A y r y D

B6)

75
Equation (Bl) is not strictly correct when the pressure P^is (as it is

likely to be) below the value which would produce choking. The error

in using equation (Bl) for subsonic flow is not great, however, because

the upstream Mach number for a given mass flow rate and fL/D depends

only slightly on the discharge mach number. The following example

illustrates this point:

Let fL/D = 15 and the discharge mach number M = 0. 57.

d

Fanno flow calculations for Y = 1.4 gives an upstream mach number

of 0. 194. When the discharge mach number is sonic {M^ = 1), then

- 0. 197 -- only 1. 6% higher. However, the corresponding pressure

ratios are quite different, being P /P, = 3 for the subsonic and P /P, = Id Id

5. 5 for the sonic case. Thus, equation (Bl) which indicates that the

upstream mach number is independent of the pressure ratio is approximately correct.

The excess vapor formation rate w is that which would result

ex

from liquid flows into the warm pipe faster than the rate which would result

in steady cooldown. Such would be the case if the entering liquid were

subcooled; then vaporization, which limits the inflow, would be delayed. The

excess vapor formation rate is:

%rr- V La

\^ oc -2 Ifi — (B7)

where L is the added heat transfer length, Ah is the heat of vaporiq V

zation and F is some fraction of the enthalpy change of the gas, Ah , s between the saturation temperature and ambient temperature.

The heat transfer length is assumed proportional to a reference

liquid velocity U. and the saturation delay time t i

' sd

L OCU, t (B8)

q * sd

76
The delay time, i. e. , the time required for a mass of fluid

entering the warm region to become saturated, is

'.-\.(^ (-

I

where ^h^^ is the subcooling enthalpy, q is the heat flux per unit

surface area andL^^s a length corresponding to the excess mass of

fluid entering. L^^^s an effective heat transfer length during the time

t If we assume L /L = C then

sd ex ex

We assume the reference liquid velocity is proportional to

the velocity of liquid before saturation, the vapor and gas in the pipe

merely being displaced by the liquid. An additional restriction is

imposed by a valve which may be in the process of opening. Alternately,

a pump starting up may be thought of as a constant pressure source

followed by a variable restriction.

2t 2 t ^

1 V , sd where R = -1, t ^ ~r—

V t , V ^ 2

sd

^ 2

K is a restriction factor.

Substitution of (B8) and (B9) into (B7) gives

c -Ahis^^ t tL ,Bii,

where C is a new constant of proportionality which includes C . 77
Assume;

(BIZ)

where — is the pipe relative roughness

For an ideal gas p

1

where

^g RT

From {BIO), (BU) and (B12) and (B13) we get

c, {A + ^s)

(B13)

(B14)

fc

1

The fraction of superheat F was determined from the detailed computer

analyses for nitrogen and hydrogen as 0. 43. This value was considered

constant. Also from the computer analysis liquid and gas friction factors

e vary from 0, 01 to 0. 014 for an apparatus in which — — 0. 0001. There- D

fore, assuming an average f of 0. 012, we get C^, and = 0, 26.

From liquid nitrogen experimental data for short valve opening

time (t < t JZ)

V sd

= 0. 326

From liquid nitrogen data with 16 second valve opening time

2K = 0. 624

78
Comparisons of peak pressures from equation (B14) (solid,

and dashed lines) with experimental data points are shown in figures

Bl through B5. In all cases, the experimental points symbolized bycircles are for various degrees of subcooling with highest peak

pressures corresponding to maximum subcooling (storage temperature

at atmospheric boiling point). The solid lines also correspond to

maximum subcooling in equation (B14).

The square symbols and dashed lines denote saturated inlet

liquid. It may be seen from these figures that the correlation gives

upper and lower limits of peak pressure which envelope eventually al

of the experimental data as desired.

79
o. Qg 30

LlI crID

</) CO

LU

cr

UJ

a:3

CO

<

UJ

Q.

20 —

10 -

O Experimental data, subcooled

and partially saturated liquid

Experimental data,

saturated liquid -— Equation B (14),

maximum subcooling

Equation B(I4)

saturated liquid

2 4 6

INLET PRESSURE RATIO, P/P^

Figure Bl. Peak surge pressure for liquid nitrogen in a 61 m (200 ft),

1. 6 cm (0. 625 in) OD copper tube transfer line.

80
INLET PRESSURE RATIO, P^/P^

Figure B2. Peak surge pressure for subcooled nitrogen in a 46 m (150 ft),

1. 6 cm (0. 625 in) OD copper transfer line.

81
g

i

INLET PRESSURE RATIO. P,/P^

Figure B3. Peak surge pressure for liquid nitrogen in a 25 m (82 ft),

1. 6 cm (0. 625 in) OD copper transfer line.

82
Figure B4. Peak surge pressure for liquid nitrogen in a 7. 6 m (25 ft),

1. 6 cm (0. 625 in) OD copper transfer line.

83
40 rS

a. a.q 30 -

UJ

crw 20

UJ

e>

q:z>

</> <

LU

0.

10 —

Experimental dota, subcooled

and partially saturated liquid.

Experimental data,

saturated liquid.

Equation B 14

,

maximum subcooling.

Equation B 14,

saturated liquid.

1_ L

2 4 6 8

INLET PRESSURE RATIO. Pj/Pd

10

Figure B5. Peak surge pressure for liquid hydrogen in a 61 m (200 ft),

1. 6 cm (0. 625 in) OD copper transfer line.

84
Appendix C. Loading of the Minicomputer

The method of loading programs into the minicomputer is described

in Section 3.3 of the manual "How to Use the NOVA Computers" (1971).

This appendix is an elaboration of the procedure described there.

The Binary Loader

The binary loader is usually in the minicomputer and is not

destroyed by any of the programs. For that reason, following the

procedure below should be sufficient to load any program in the minicomputer.

However, occasionally a sharp spike on the power lines or a malfunction of the memory in the computer can cause the binary loader

to be destroyed. If this should happen, the "Bootstrapping" procedure

must be performed first.

1 . Preparing the teletype

The minicomputer and CRT display must be turned on but not

running and the CRT display LOCAL / LINE switch set to LOCAL. The

teletype is plugged into the back of the CRT display. Turn the teletype

power switch, LINE/OFF/LOCAL, to LINE. With the teletype reader

switch in OFF position, place the paper tape containing the program

in the reader with the tape coming out toward the front of the teletype

and the narrower side from the sprocket holes in the tape toward the

outside of the teletype. Position the tape so that unpunched tape is over

the read position. Set the reader switch to ON.

85
page 2

2 . Loading the Program

On the minicomputer, the upper row of switches is called the

Switch Register , and are labeled 0 through 15. The lower row of

switches are all momentary switches used for control and their

functions are listed on the panel.

Set the Switch Register 0, 1, 2 down and 3 thru 15 up. Press

control switch RESET and then START. The teletype should start

reading paper tape. At the end of each binary block on the tape, the

printer mechanism should receive some null character and,

thus, cycle or ''chuckle''. Should it fail to do this, back up to the

beginning of the paper tape and try again. Should it still fail it may be necessary to follow the "Bootstrapping" procedure

and then try again. If the program loads correctly, it may self

start or it may halt the computer. If the computer halts, set

all the Switch Register switches down except 14, which must be up,

and press START. If subsequent operations are to be between the

minicomputer and the CRT display, the LOCAL /LINE switch on

the CRT should be set to LINE before pressing START, and the

teletype turned to OFF.

If the computer halts in the middle of the tape reading, the

teletype has made an error while reading the tape. It is not necessary

to start the tape over completely. Merely back the tape up at least

one block and start the computer again. The beginning of a block

is fairly easy to recognize. It consists of two frames with no punches

in the tape except the sprocket hole followed by a frame with at least

the four top most positions punched followed by a frame with all

positions punched. Reposition the tape on one of the two unpunched

positions, set the teletype reader to ON and push START on the

minicomputer. If the teletype fails to start ''Chuckling", the tape

should be restarted at the beginning.

86
page 3

Bootstrapping

It may occasionally be necessary to restart the minicomputer

from a completely obliterated condition. To do this, turn on the

minicomputer and the CRT display. Set the CRT display LOCAL/LINE

switch to LOCAL. Prepare the teletype with the tape marked

"CHUCKLING LOADER" in the reader just as you would for any

other program tape. Next, follow the instructions in TABLE A-1.

After the last line of the table has been executed the computer should

read the tape and stop at the end. It will not "chuckle" the teletype.

If it does not, read the tape the computer or teletype is likely in

need of repair. If it does read the tape correctly, proceed to

load program as desqxibed in the section. Binary Loader.

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FORM NBS-114A (1-71)

1 U.S. DEPT. OF COMM. 1. PUBLICATION OR REPORT NO. 2. Gov't Accession

BIBLIOGRAPHIC DATA NBSIR 74-366

SHEET

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Study of Cryogenic Propellant Systems for Loading

the Space Shuttle

5. Publication Date April 1974

6. Performing Organization Code

7. AUTHOR{s) R. O. Voth, W, G. Steward, and

W. H. Hall

8. Performing Organization

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

Washington, D. C. 20234

10. Project/Task/Work Unit No. 2750458

11. Contract/Grant No. CC-03420A

12. Sponsoring Organization Name and Address

National Aeronautics and Space Adraini strati on

John F. Kennedy Space Center

Kennedy Space Center, Florida 32899

13. Type of Report & Period

Covered

14, Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) Computer programs have been written to model the liquid oxygen loading

system for the space shuttle. The programs allow selection of input data through

graphic displays which schematically depict the part of the system being modeled.

The computed output is also displayed in the form of graphs and printed messages.

Any one of six computation options may be selected. The first four of these

pertain to thermal stresses, pressure surges, cooldown times, flow rates and

pressures during cooldown. Options five and six deal with possible water hammer

effects due to closing of valves, steady flow and transient response to changes

in operating conditions after cooldown.

Procedures are given for operation of the graphic display unit and

mini computer.

17. KEY WORDS (Alphabetical order, separated by semicolons)

Computer modeling; cooldown; cryogenic flow; stresses; surges; transient flow;

water hammer.

18. AVAILABILITY STATEMENT

[x] UNLIMITED.

I I FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE

TO NTIS.

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

22. Price

USCOMM-DC 66244-P71

USCOMH - ERL