EXPERIMENTAL MASS FLOW RATE, Ibm/hr

20

35
30
25
20
AS

05

ee ee

10 000
Le = 1000 PS
E EQUATION LOH AP YS

(a) 17 600 Lohms.

KA
ao ,w 9
a >e Y

40 000
LEE EQUATION = Toor ar

| J | | |

= OO
A
a

(b) 41 000 Lohms.

D> Vv

40_ 000
LEE EQUATION = Tope VP

(c) 80 000 Lohms.

> <
10 000 7
LEE EQUATION = OHM AP *S

| | l ! !

10 20 30 40 50
PRESSURE DIFFERENCE ACROSS THE VISCO JET, psid

(d) 243 000 Lohms.
Figure 5. - Nitrogen flow through Visco Jet.

19

60

vaDpoon VADbOO vaDpoon

vaDPon

VISCO JET INLET CONDITIONS
PRESSURE, TEMPERATURE,
psia R

S&S8Sss

VISCO JET INLET CONDITIONS,
PRESSURE, TEMPERATURE,
a oR

psi

60
60
60
60
45
30

VISCO JET INLET CONDITIONS:
PRESSURE, TEMPERATURE,

psia

S&SSSss

VISCO JET INLET CONDITIONS
PRESSURE, TEMPERATURE,
ia oR

60
60
60
60
45
30

120
129
138
148
162
157
150

130
138
148
162
157
150

*R

420
128
138
146
162
158
150

120
138
148
162
157
150


TABLE II. - VISCO JET DATA

(a) 17 600 Lohm

AP MDATA | MMOD | MLEE PIN POUT TIN TOUT TSAT xX KR
56.00 | 3.33 3.42 | 3.82 | 59.08 3.08 | 138.25 | 118.36 | 164.65 | 0.1046 1
50.86 | 3.28 3.46 | 3.64 | 58.29 7.42 | 138.07 | 128.63 | 164.36 -0486 1
44.13 | 3.14 3.39 | 3.39 | 58.19 | 14.06 | 138.10 | 138.08 | 164.33 -0000 2
29.86 | 2.61 2.79 | 2.79 | 57.54 | 27.68 | 138.04 | 138.59 | 164.08 -0000 2
18.68 | 2.12 2.21 | 2.21 | 57.58 | 38.91 | 138.07 | 138.53 | 164.10 -0000 2
9.74 | 1.52 1.59 | 1.59 | 56.67 | 46.93 | 138.06 | 138.30 | 163.75 -0000 2
15.53 | 1.96 2.04 | 2.04 | 62.41 | 46.88 | 128.57 | 128.72 | 165.85 -0000 2
22.82 | 2.36 2.47 | 2.47 | 62.25 |} 39.43 | 129.40 | 129.96 | 165.80 -0000 2
32.83 | 2.78 2.96 | 2.96 | 61.73 | 28.90 | 129.90 | 130.36 | 165.61 .0000 2
42.95 | 3.21 3.39 | 3.39 | 57.23 14.28 | 129.78 | 130.37 | 163.97 -0000 2
53.56 | 3.57 3.77 | 3.78 | 60.99 7.43 | 129.96 | 128.65 | 165.35 -0033 1
54.45 | 3.49 3.65 | 3.81 | 58.75 4.30 | 130.26 | 122.04 | 164.53 -0418 1
57.72 | 3.56 3.70 | 3.93 | 60.83 3.11 | 129.70 | 118.85 | 165.29 -0579 1
57.32 | 3.81 3.89 | 3.96 | 60.49 3.17 | 122.22 | 118.89 | 165.17 -0164 1
52.38 | 3.60 3.78 | 3.78 | 59.57 7.19 | 121.85 | 122.77 | 164.83 -0000 2
41.75 | 3.22 3.38 | 3.38 | 57.23 | 15.47 | 121.44 | 122.19 | 163.97 .0000 2
28.48 | 2.77 2.80 | 2.80 | 56.23 | 27.76 | 120.41 | 120.95 | 163.59 -0000 2
15.97 | 2.11 2.10 | 2.10 | 55.47 | 39.51 | 119.55 | 120.20 | 163.30 .0000 2
8.99 | 1.55 1.57 | 1.57 | 59.10 |} 50.11 } 120.79 | 121.26 | 164.66 .0000 2
55.40 | 3.09 3.14 | 3.74 | 58.35 2.95 | 148.13 | 118.20 | 164.38 .1596 1
50.29 | 3.04 3.20 | 3.56 | 57.94 7.64 | 148.19 | 128.70 | 164.23 -1025 1
43.11 | 2.96 3.15 | 3.30 | 57.44 | 14.32 | 147.09 | 137.75 | 164.05 -0480 1
28.06 | 2.52 2.66 | 2.66 | 56.64 | 28.59 | 147.49 | 147.72 | 163.74 .0000 2
19.54 } 2.10 2,22 } 2.22 | 58.27 | 38.74 | 147.98 | 148.19 | 164.35 -0000 2
9.48 | 1.47 1.55 | 1.55 | 57.72 | 48.24 | 148.62 | 148.66 | 164.15 -0000 2
49.17 | 1.20 1.46 | 1.48 | 57.29 | 48.12 | 162.77 | 159.07 | 163.99 -0156 1
17.87 |} 1.51 1.99 | 2.07 | 56.72 | 38.85 | 162.58 | 154.83 | 163.77 -0404 1
29.87 | 1.77 2.46 | 2.67 | 57.08 | 27.20 | 162.78 | 148.14 | 163.91 .0799 1
42.17 | 2.01 2.74 | 3.18 | 56.45 | 14.28 | 162.64 | 137.83 | 163.67 -1366 1
48.93 | 2.05 2.79 | 3.42 | 56.24 7.31 | 162.47 | 128.26 | 163.59 -1840 1
53.57 | 2.18 2.72 | 3.58 | 56.18 2.61 | 162.49 | 116.77 | 163.57 +2419 1
42.79 | 2.01 2.53 | 3.23 | 45.33 2.54 | 157.70 | 116.37 | 159.10 +2175 1
37.38 | 1.85 2.57 | 3.02 | 45.20 7.82 | 157.25 | 128.73 | 159.04 .1504 1
30.86 | 1.78 2.45 | 2.75 | 45.12 | 14.26 | 157.30 | 137.70 | 159.00 . 1060 1
17.42 | 1.45 1.97 | 2.06 | 44.91 | 27.50 | 157.30 | 148.28 | 158.91 -0460 1
5.00 -92 1.10 | 1.10 | 44.93 | 39.93 | 157.38 | 155.24 | 158.92 .0050 1
3.26 72 -90 -90 | 30.83 | 27.57 | 150.55 | 148.29 | 151.67 ,0054 1
10.35 | 1.11 1.56 | 1.61 | 31.70 | 21.35 | 150.74 | 143.88 | 152.18 +0323 1
17.04 | 1.36 1.92 | 2.06 | 31.28 | 14.25 | 150.63 | 137.69 | 151.93 -0680 1
23.91 | 1.52 2.16 | 2.45 | 31.36 7.45 | 150.55 | 128.31 | 151.98 .1166 1

aThe following three sets of data are with partially blocked Visco Jet.

13



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piping are also pneumatically actuated but not vacuum jacketed. Vapor vent
on/off valves for routing the flow through a bank of flow meters are controlled
by solenoid valves that are housed within a nitrogen-purged box.

There are two Visco Jets mounted within the test chamber. The one labeled
primary is the test article while the other labeled secondary is part of a heat
exchanger system. Liquid nitrogen from the supply dewar enters the test cham-
ber flow system through a flange feed through port and flows in an upward
direction where it is divided into three parts by a cross in the line. The
test fluid that flows through the primary Visco Jet turns into downward flow
where it traverses the heat exchanger, an electrically heated coil, the primary
Visco Jet, the vapor trap coil, the air heat exchanger, a bank of flowmeters
and finally discharges through an air ejector to the vent system. The heater
coil between the heat exchanger and the primary Visco Jet is used to raise the
fluid temperature, while the secondary Visco Jet discharging through the heat
exchanger is used to cool the inlet test fluid. By selectively using the heat
exchanger and the heater coil, it is possible to condition the test fluid to
cover a wide range of inlet temperatures from high subcooling to near saturated
inlet conditions. The vapor trap coil, downstream of the primary Visco jet, is
installed to prevent buoyancy driven vapor, located outside the vacuum tank,
from coming up the tube to the temperature measuring station, downstream of the
primary Visco Jet.

The test fluid that flows downstream of the Visco Jet is completely vapor-
ized in an air heat exchanger prior to its passage through a bank of gas flow
meters discharging through an atmospheric vent. The primary ejector pump,
between the flow meters and the vent, is operated to reduce the line pressure
below 1 atm to simulate low vacuum space conditions.

The cross in the line diverts some of the fluid through the secondary
Visco Jet to the outer flow passage of the double tube type heat exchanger, and
then discharges through the secondary air ejector to the vent system. The bal-
ance of the fluid separated from the inlet flow by the cross in the line,
labeled bypass flow in figure 1, enters the coils of the cold wall and dis-
charges to the atmosphere. Figure 2 is a photograph of the exterior view of
the cold wall showing the coils brazed to the wall itself. The wall is essen-
tially a thin stainless shell surrounded by an aluminized mylar thermal shield
(not shown) to reduce radiation from the test chamber wall to the cold wall.

A nominal bypass flow rate was determined during initial operations based on
maintaining a constant cold wall temperature.

A photograph of the plumbing within the test chamber with the cold wall
removed is shown in figure 3. The lines made of 1/4-in. seamless tubing with
a 0.28 wall thickness are shaped to relieve stress during thermal cycling.

Test Article

The Joule-Thomson device (Visco Jet) used in this study is essentially a
group of orifices in series encapsulated in a fitting for installation within a
flow system. Figure 4 taken from the Lee Technical Hydraulic Handbook (ref. 2)
is a schematic of the orifice arrangement within a disc. The resistance to
flow is generated by complex flow passages between a series of these discs con-
taining spin chambers mounted in the fitting perpendicular to flow. The fluid


EXPERIMENTAL MASS FLOW RATE,
Ibmv/nr

EXPERIMENTAL MASS FLOW RATE,
tbevhr

VISCO JET EXIT
CONDITIONS

© SINGLE PHASE
(1 TWO-PHASE

10 000
LOHM
| roto til nt }
3 8 13 18
PREDICTED FLOW RATE WITH LEE EQUATION, lbm/hr

LEE EQUATION =

3

Figure 6. - Experimental and predicted values with Lee
equation, 41 000 Lohm’s.

VISCO JET EXIT
CONDITIONS

© SINGLE PHASE
( TWO-PHASE

MODIFIED. __, 10.000, SH.
LEE EQUATION ~ Ton ¥4P *S (1°)
L a L J

3 4 8 8 1.0 18
PREDICTED FLOW RATE WITH MODIFIED LEE EQUATION,
tomvar

3 1

Figure 7. - Experimental and predicted values with modified
Lee equation, 41 000 Lohm's.

20


Nationat Aeronautics and
‘Space Administration

Report Documentation Page

- Report No.
NASA TM-103121

2. Government Accession No.

e

Recipient's Catalog No.

s

|. Title and Subtitle

Acquisition and Correlation of Cryogenic Nitrogen Mass Flow
Data Through a Multiple Orifice Joule-Thomson Device

a

Report Date
May 1990

2

. Performing Organization Code

~

'. Author(s)

S. Stephen Papell, Naseem H. Saiyed, and Ted W. Nyland

@

. Performing Organization Report No.

E-5449

©

Lewis Research Center
Cleveland, Ohio 44135-3191

}. Performing Organization Name and Address

National Aeronautics and Space Administration

). Work Unit No.

591-21

. Contract or Grant No.

12. Sponsoring Agency Name and Address

National Aeronautics and Space Administration
Washington, D.C. 20546-0001

13.

Type of Report and Period Covered
Technical Memorandum

. Sponsoring Agency Code

15. Supplementary Notes

S. Stephen Papell, Analex Corporation, NASA Lewis Research Center, 21755 Brookpark Road, Fairview Park,
Ohio 44126. Naseem H. Saiyed and Ted W. Nyland, NASA Lewis Research Center.

16. Abstract

values.

Liquid nitrogen mass flow rate, pressure drop, and temperature drop data have been obtained for a series of
multiple orifice Joule-Thomson devices, known as Visco Jets, over a wide range of flow resistance. The test rig
used to acquire the data was designed to minimize heat transfer so that fluid expansion through the Visco Jets
would be isenthalpic. The data include a range of fluid inlet pressures from 30 to 60 psia, fluid inlet temperatures
from 118 to 164 °R, outlet pressures from 2.8 to 55.8 psia, outlet temperatures from 117 to 162 °R and flow
rate from 0.04 to 4.0 Ibm/hr of nitrogen. A flow rate equation supplied by the manufacturer was found to
accurately predict single-phase (noncavitating) liquid nitrogen flow through the Visco Jets. For cavitating flow,
the manufacturer’s equation was found to be inaccurate. Greatly improved results were achieved with a modified
version of the single-phase equation. The modification consists of a multiplication factor to the manufacturer’s
equation equal to one minus the downstream quality based on an isenthalpic expansion of the fluid across the
Visco Jet. For a range of flow resistances represented by Visco Jet Lohm ratings between 17 600 and 80 000,
100 percent of the single-phase data and 85 percent of the two-phase data fall within + 10 percent of predicted

17. Key Words (Suggested by Author(s)
Cryogenic liquid
Isenthalpic expansion
Joule-Thomson device
Multiple orifices

18. Distribution Statement

Unclassified — Unlimited
Subject Category 34

19. Security Classif. (of this report)
Unclassified

20. Security Classif. (of this page)
Unclassified

21.

No. of pages 22. Price*
22 A03

NASA FORM 1626 OCT a6

“For sale by the National Technical Information Service, Springfield, Virginia 22161



VAPOR FLOW

SECONDARY j 7]}— primary ONOFE VALVES
VISCO JET FLOW-~ || {] VISCOJET FLOW
s
f
Hi
qi i] TCOLD WALL i
fl i
H '] FLOW METERS me
VACUUM CHAMBER — |! 1 \
‘ NL | t—VAPOR \
! [Ts i] TRAP
Col
H Tout] [+7 i py oe EP PRIMARY
VACUUM GAUGE |¢] Puy gl y EJECTOR
ql ! PRESSURE PUMP
fl = REGULAT!
Sea oe ea A
=|
ip AIR HEAT
Pump our] | |'ou EXCHANGER
PORT
LN, ae ‘SECONDARY
SUPPLY ATMOSPHERE —py— —_-EEcTOR
DEWAR PUMP.
VACUUM JACKET LIQUID SECONDARY EJECTOR
FUUID TRANSFER FLOW a aN
INE CONTROL ‘N\
VALVE PRIMARY EJECTOR. “\ PRESSURE
REGULATING
—O— COLD WALL COILS VALVES:

> ~ MULTILAYER INSULATION
qr HEATER COIL
SECONDARY VISCO JET
PRIMARY VISCO JET
ANY DOUBLE TUBE HEAT EXCHANGER

Figure 1. - Joute-Thomson device test rig schematic.

17


An examination of the reliable data in figure 8, covering a range of
Visco Jet Lohm ratings between 17 600 to 80 000, shows that 100 percent of the
single-phase data and 85 percent of the two-phase data fall within the +10 per-
cent scatter band. An attempt should be made during the remainder of the test
program to reduce the scatter in the data correlation and to extend the range
of correlated Visco Jet Lohm ratings. In addition, an attempt should be made
to positively identify the cause of flow blockage within the body of the Visco
Jet and evaluate solutions for its prevention.

SUMMARY OF RESULTS

A test rig was constructed capable of obtaining liquid hydrogen and liquid
nitrogen flow rate, pressure drop, and temperature drop data across a series of
four Visco Jets with flow resistances represented by Lohm ratings of 17 000,

41 000, 80 000, and 243 000. The liquid nitrogen results are reported herein.
The data includes a range of inlet pressures from 30 to 60 psia, inlet tempera-
tures from 118 to 164 °R, outlet pressures from 2.8 to 55.8 psia, outlet tem-
peratures from 117 to 162 °R and flow rates from 0.04 to 4.0 lbm/hr.

The data were applied to the Lee equation supplied by the Visco Jet manu-
facturer that predicts hydraulic fluids flow rates with the following results:

1. For fluid resistances identified by Visco Jet Lohm ratings from 17 600
to 80 000, the Lee equation was found to predict 100 percent of the single-
phase liquid nitrogen data within +10 percent accuracy, but overpredicted the
two-phase data by as much as 30 percent.

2. A two-phase data correlation scheme was developed based on the genera-
tion of vapor within the body of the Visco Jet that results in a reduction in
flow rate. The Lee equation, modified with a multiplication term equal to one
minus the quality based on an isenthalpic expansion, predicts 85 percent of the
reliable two-phase data within +10 percent accuracy for Visco Jet Lohm ratings
from 17 600 to 80000.

3. The extremely low flow rate data obtained with the 24 300 Lohm rating
Visco Jet was not included in the percent scatter evaluation because of
increased data uncertainty and larger percentage errors in measurements at low
flow rates.

4. Suggestions are made for a continuation of the test program to reduce
the scatter in the data correlation and to further investigate the phenomenon
of partial flow blockage within the body of the Visco Jet that occurred several
times during the data runs.


in pressure over a 24-hr time interval. The vacuum was continuously monitored
with a vacuum gage during the testing. After the integrity of the vacuum sys-
tem was established, the system piping was purged with gaseous helium to elimi-
nate water vapor and air from the system. The liquid nitrogen supply dewar was
then pressurized by nitrogen boil-off through an external vaporizer to a pres-
sure above that required for the test. Chilldown of the entire test rig was
achieved by flowing liquid nitrogen through the system piping.

The controlled parameters for setting up test conditions were inlet and
exit Visco Jet pressures, inlet Visco Jet temperature, and bypass flow. A typ-
ical data run consisted of establishing a fixed inlet pressure and temperature
upstream of the Visco Jet and then varying the downstream pressure. A data
point was recorded at discrete exit pressure levels for 30 readings at 5-sec
intervals for averaging and to establish the steady-state nature of the flow.

Data were obtained over a range of inlet pressures from 30 to 60 psia,
inlet temperatures from 118 to 164 °R, outlet pressures from 2.8 to 55.8 psia,
outlet temperatures from 117 to 162 °R, and flow rates from 0.04 to 4.0 lbm/hr
of nitrogen. All the basic data are listed in tables II{a) to (d) for Visco
Jets with flow resistances represented by Lohm ratings of 17 000, 41 000,

80 000, and 243 000, respectively.

DATA PRESENTATION

Four sets of liquid nitrogen mass flow data, as a function of pressure
drop across the Visco Jets, are presented in figures 5(a) to (d). Each suc-
ceeding figure from a to d is for Visco Jets with increasing resistance to
flow. The data for the Visco Jet with the least resistance to flow having a
Lohm rating of 17 600 is shown in figure 5(a). The various symbols on the plot
identify seven data runs at three different inlet pressures. The 60 psia data
includes five data runs at inlet temperatures from 120 to 162 °R that cover a
wide range of inlet subcooling, up to near-saturated inlet conditions. In con-
trast, the 45 and 30 psia data are limited to near saturated inlet conditions.
The region between the two lines on the plot represents the locus of the Lee
equation from reference 2 that predicts noncavitating liquid flow through the
Visco Jets. The 5 percent spread in the band is caused by fluid density dif-
ferences at inlet conditions (i.e., 120 to 162 °R). It is apparent that a good
percentage of the data represented by a square, a circle, a diamond, and an
upright triangle falls between these two lines.

For fluid inlet conditions of 60 psia and 120 °R representing relatively
high inlet subcooling, the open squared data follows the Lee equation over most
of the range of pressure differences across the Visco Jet. However, as the
subcooling is decreased by raising the inlet temperature to 129 °R, a departure
from the Lee equation is noted by a drop in the flow rate above a pressure dif-
ference of 50 psid. Further decreases in subcooling, as noted by increasing
the inlet temperature to 148 °R, move the departure point to even lower values
of pressure drop. At near-saturated inlet conditions of 162 °R, the decrease
in flow rate from that predicted by the Lee equation occurs at a pressure drop
of 5 psid. Both the 45 and 30 psia data at near-saturated inlet conditions
also drop off at about the same pressure differences.

An additional data trend noted in figure 5(a) is the absence of an inlet
pressure effect on the near-saturated inlet data. All three near-saturated

6


changes direction many times resulting in a pressure drop much greater than
would be obtained with a normal metering hole of the same diameter.

Four sets of Visco Jets, with different Lohm ratings each, were purchased
from the Lee Company. Each set consisted of six individual Visco Jet units of
similar Lohm rating. Each Visco Jet was calibrated with water and the results
checked against the nominal Lohm ratings supplied by the manufacturers. Table I
lists the manufacturer's specified and the calibrated Lohm ratings for each test
article. Although differences varied as much as 11 percent, the Visco Jets
chosen for this study, as noted in the table, are within +#3.5 percent of the
nominal values.

Instrumentation

The flow system schematic of the Visco Jet test apparatus (fig. 1) shows
the location of the instrumentation. Within the vacuum chamber, fluid pres-
sure and temperature measurements were obtained upstream and downstream of the
primary Visco Jet under test. Additional temperature measurements were made
of the primary Visco Jet body and the bypass fluid. Temperature and pressure
measurements were also made within the support, plumbing upstream and down-
stream the bank of flow meters to assure their operation within design specifi-
cations. The pressure measurements were made with strain gage type transducers
and temperature measurements with silicon diode sensors. Instrumentation cali-
brations were made prior to the initial data runs and after the testing was
completed. During the testing, continuous checks were made by comparing the
outputs of instruments that were under identical test conditions.

Mass flow rates of the test fluid through the primary Visco Jet, after
warming to ambient conditions, were measured by a bank of four thermal conduc-
tivity type flow meters. Because of the wide range of flows required for test-
ing, each flow meter covered a specific range of flows. The flow meter used
for a particular test was selected by valving to maintain the readings within
its operating range.

Data Acquisition System

The Visco Jet test stand, mounted on a moveable cart along with valves,
plumbing and flow meters, was stationed within a test cell. Remote operation
of the rig was achieved through a control panel located in the control room.
The data acquisition system was an analog-to-digital multiplexor connected to
a dedicated personal computer (PC). The multiplexor received voltage signals
from the test rig that were then digitized and converted to integer counts. A
computer code then converted the counts to engineering units for data manipula-
tion. Online test conditions were displayed in engineering units on the PC
monitor and the data was stored on the PC's hard disc. The data stored in this
manner was then transferred to a floppy disc for processing.

EXPERIMENTAL PROCEDURE
Prior to testing, the chamber housing the Visco Jet was evacuated to about
35 pm of mercury at which time the vacuum pump was isolated from the rig. The

integrity of the vacuum system was established by noting an insignificant gain

5


S.. fag TEST
BYPASS ‘el FLUID
FLUID LINE Sty z oy LINE
Cc SECONDARY
VISCO JET

HEAT
EXCHANGER

DOWN FLOW

TEST FLUID LINE

Vag PRIMARY.
VISCO JI

sf j : [C-90-01565.
Figure 2. - LN2 Joule-Thomson device test rig Figure 3. - Apparatus surrounded by the LNo cold wall

VISCO JET DETAILS.
(Taken from the Lee Technical Hydraulic Handbook)

The Lee Visco Jets contain a large number of spin chambers and tangential slots
arranged in a series to provide a uniquely restrictive, tortuous path for the fiuid
medium. Flow enter each “stage” at the center of the pattern. From that point, it
asses into a spin chamber via a rectangular slot. Within the chamber, the spinning
liquid creates a back pressure which varies with the viscosity of the liquid. The
liquid then passes through a restriction with a circular cross-section to the center of
another spin chamber on the opposite face of the “stage”. This spin chamber has
an exiting tangential slot which is in the opposite direction from the previous
‘entrance slot. The changing of direction forces the liquid to come to rest before it
makes its exit from the deceleration chamber. This process is repeated within all
the series of cavities of one “stage” until the liquid leaves through the final circular
¢r0ss-section hole at the center of the pattern. Within practical limits, additionat
stages can be assembled to provide increased Lohm rating, or higher resistance to
flow.

‘An independent Visco
“stage” consists of throe
different patterns which
are combined to form a
‘complex fluid passageway,

FLUID FLOW a ‘Some Lee Visco Jets are made from solid stainless steel discs, while others are
While passing through fabricated from photo-etched stainless steel plates which are bonded together to
the tortuous path produce a homogenous leak-proof product. All Visco elements are rigidly and
within each "stage" permanently retained in their respective inserts, cartridges, or linemounts. Standard
the fluid encounters. Lee Visco Jets are calibrated to the noted Lohm ratings in both directions. Lee
various orifices and Visco Jets with minimum passages of 0.032" or less are protected at each end by
spin chambers, and ‘an appropriately sized filter screen.

changes direction of

LZ rotation many times.

Permission is hereby granted to use, copy and reproduce

the general engineering material, including nomograms, tables
and formulae, with the only restriction being to give credit to
‘The Lee Company if the material is published or republished.

Figure 4.

18


ht = Xhg + (1 - X)hy (2)

where ht is the inlet enthalpy, and hg and hj are the saturated gas and
liquid enthalpies at the outlet pressure, respectively. The results of the
calculations are presented in column X of table II.

The correlation procedure reported herein is based on a reduction in the
mass flux during a phase change within the body of the multiple orifice Visco
Jet. Because the quality reduces the average density of the fluid in the flow
passage, it is directly related to the reduction in flow rate. Since the mass
fraction of liquid in a two-phase system is equal to one minus the quality, a
term equal to 1 - X was used to identify the change in flow rate. The Lee
equation which has been shown to adequately predict liquid nitrogen single-
phase flow was then modified by a multiplication factor equal to 1- X to
attempt to reduce the spread in the figure 6 data. The completed data correla-
tion follows:

fa = (20.70) (apsy/2(1 - x) (3)

The result of the modification, presented in figure 7, shows a marked improve-
ment in the data correlation. Most of this particular set of data falls within
a 10 percent error band.

All four sets of Visco Jet data are plotted in figure 8 as experimental
mass flow versus predicted mass flow using the modified Lee equation. The
data, covering a wide range of flow rates, is divided by the vertical lines on
the plot into four groupings. Each group identifies the range of flow covered
by each Visco Jet with some overlap. The solid lines, encompassing a great
deal of the data, represent a +10 percent scatter band from perfect agreement.
Again, single- and two-phase data are identified by an open circle and an open
square, respectively. It is significant to note that almost all the single-
phase data fall within the 10 percent scatter band except for two data points
in the extremely low flow rate region. The balance of the single-phase data
in this region is also high compared to the other three sets of single-phase
data suggesting some additional uncertainty in the data measurements, possibly
due to the extremely low flow rate measurements. Although the absolute error
is comparable for all sets of data, the percent error is much larger in the
low flow rate region. In addition, the two-phase data in this low flow rate
region also appears high.

At the opposite end of the plot the data represented by a solid square,
obtained with the 17 600 Lohm rating Visco Jet, falls significantly outside of
the 10 percent scatter band. This data, obtained consecutively at the end of a
test run, is thought to be erroneous due to the phenomenon of partial blockage
within the Visco Jet. The suspect data is identified as such in the tabulated
basic data. Partial blockage also occurred on two other occasions with differ-
ent Visco Jets during data acquisition. For these cases, the problem was iden-
tified at the time and the runs were repeated after allowing the rig to warm up
to ambient conditions. The blockage phenomenon is tentatively attributed to
freeze up trace liquid contaminates in the test fluid. When blockage became
apparent during data acquisition, the test rig would be allowed to warm up to
ambient conditions, thus allowing the contaminates to thaw and pass through the
Visco Jet.


NASA Technical Memorandum 103121

Acquisition and Correlation of Cryogenic
Nitrogen Mass Flow Data

Through a Multiple Orifice
Joule-Thomson Device

S. Stephen Papell

Analex Corporation

NASA Lewis Research Center
Fairview Park, Ohio

and
Naseem H. Saiyed and Ted W. Nyland
National Aeronautics and Space Administration

Lewis Research Center
Cleveland, Ohio

May 1990

NASA


most of the boxes are to the right, then the modification should be to reduce
the predicted values and vice versa.

The results of this technique when applied to the current experiment are
shown in figure 9 for 41 000 Lohm. The solid circle indicates the data point
if there were no errors present and the box is explained above. As indicated,
the predicted errors are slightly less than the experimental errors. The line
slope of 1 crosses the majority of the boxes, thus indicating the validity of
the modified Lee equation within experimental and theoretical errors.

REFERENCES
1. Anderson J.E.; and Eberhardt, R.N.: Cryogenic Storage System Development
For Long Term Space Missions. AIAA/SAE/ASME Joint Propulsion Conference,
15th, AIAA, New York, 1979, paper No. 79-1261.

2. Technical Hydraulic Handbook. Seventh edition, Lee Company, Westbrook, CT,
1984.

3. Holman J.P.: Experimental Methods for Engineers. Fourth edition, McGraw
Hill, 1984.

11


APPENDIX — Error Analysis

The comparison of experimental data with theory is valid only when all
the errors in the measurements and predicted calculations are considered. The
value that a device measures can deviate from the true value of the measure-
ment due to experimental errors, Examples of such errors are the signal errors
(transducer, signal conditioner, amplifier, recorder), sensitivity drift, oper~
ation of device beyond its normal range, electronic noise, human error, etc.
Therefore, in order to have confidence in the measured value, a range within
which the true value may exist (device accuracy) is determined by calibrating
the device. In this experiment these errors were as follows. The accuracies
of absolute pressure measurements across the Visco Jet were +1 percent of full
scale value (100 psia), +1.8 °R for temperature measurements, and +1 percent
of full scale for the flow meters downstream of the Visco Jet. The flow meter
range for the 17 600, 41 000 and 80 000 Lohm Visco Jets was 0 to 7.5 lbm/hr and
for 243 000 Lohm Visco Jet was 0 to 0.75 lbm/hr.

The uncertainty in the predicted calculations is referred to as analytical
model accuracy. While the errors due to signal conditioning, drift, etc. accu-
mulate to become device accuracy, the uncertainties in the input parameters to
the theoretical model such as pressure, temperature, etc. accumulate to become
analytical model accuracies. A widely accepted method of determining the
model accuracy Qf is given in reference 3 as

2 2 2 21?

op = [aha + QyoPra) + (ygFyg) ts 2 + OxnF en) ] (4)
where F = F(x,, x9, Xj, . . ., Xn) the analytical model with n independent
parameters. Fy is the partial derivative of F with respect to input param-
eter x. The approach was applied to the semiempirical model used for the
analysis in this experiment (eq. (3)). It showed that the errors in absolute
pressures were minute in relation to the +3.5 percent error in the Lohm rating.
Consequently, the analytical model accuracy was nearly identical to the per-
centage error in the Lohm rating.

Once all the accuracies are determined, the following technique is used
to compare the predicted values to the experimental values. The ordinate of a
graph is labeled as experimental value and the abscissa as the predicted value.
A line with a slope of 1 is drawn covering the full range of the graph. The
experimental and predicted values are graphed as well as their uncertainty val-
ues. For a given experimental and predicted point on the graph, the uncer-
tainty in the experimental value gives a vertical line, whereas the uncertainty
in the predicted value gives a horizontal line through the point. A box whose
boundary coincides with the ends of the two lines is drawn around the graphed
point. The box indicates the region where the true graphed point exists due to
the device and the analytical model accuracies. The shape of the box compares
the relative magnitude of the experimental to predicted errors. If the box is
a square, then the errors are numerically identical. If rectangle, however,
then the axis parallel to its length contributes more toward the total error
than the perpendicular axis. Once all the boxes are drawn, the theoretical
model is determined as validated if the line with a slope of 1 crosses the
boxes at any location. The indication to modify the predicted model is evident
if most of the boxes are to either the right or left side of the line. If

10


inlet data runs at inlet pressures of 60, 45, and 30 psia fall along the same
curve. An examination of the basic data in table II will show that the
decrease in flow from that predicted by the Lee equation coincides with down-
stream fluid temperatures equal to saturation values based on downstream pres—
sures. Consequently, the higher the inlet subcooling, the more pressure drop
is required to obtain cooling via the Joule-Thomson effect.

The data trends noted in figure 5(a) for a Visco Jet with a Lohm rating
of 17 600 are again noted in figure 5(b) for a Visco Jet with a Lohm rating of
41 000. The most significant difference is the 50 percent reduction in flow
rate due to the increased resistance to flow.

Figure 5(c) presents the data for a Visco Jet with a Lohm rating of
80 000. The trends in the data are again similar to the trends in the fig-
ure 5(b) 41 000 Lohm Visco Jet data. Again, the most significant difference
is the level of the flow rate data that drops off about 50 percent more due to
increased resistance to flow.

The fourth set of data (fig. 5(d)) was obtained with a Visco Jet having a
243 000 Lohm rating. The increased resistance to flow over the figure 5(c)
80 000 Lohm Visco Jet data results in an additional 70 percent drop in the flow
rate. Although the data trends for all four sets of data are similar, the flow
rate measurement for this set of data appears to be high. The Lee equation
for liquid flow underpredicts the single-phase flow by about 8 percent. An
increased amount of uncertainty exists for this particular set of data due to
the extremely low flow rate measurements which most likely contribute to the
offset and increased scatter in the data.

DATA CORRELATION AND DISCUSSION

The spread of the basic data in figures 5(a) to (d) shows that the Lee
equation adequately predicts a portion of the data and overpredicts the bal-
ance of the data by as much as 30 percent. In order to clearly show these
differences, the basic measured flow data were plotted versus the flow rates
obtained from the Lee equation. An examination of figure 6, which presents the
41 000 Lohm rating Visco Jet data, shows the data divided into two categories
of exit flow conditions. The data shown as a circle falls along the solid
line that represents agreement between the data and the Lee equation for non-
cavitating flow (single phase). The data shown as a square, that falls as
much as 28 percent off the line, represents cavitating flow (two-phase) exit
conditions.

The thermodynamic state of the outlet flow is determined by comparing the
fluid enthalpies across the Visco Jet. If the inlet enthalpy is greater than
the saturated liquid enthalpy at the outlet pressure, then quality exists in
the outlet flow. The exit thermodynamic state of the fluid is identified in
column KR of table II for all the data runs. When KR = 1, the outlet fluid
is at saturated conditions and two-phase flow can exist. When KR = 2, the
outlet fluid is subcooled and only single-phase flow exists.

Isenthalpic expansion calculations were then made for all the two-phase
data to determine the extent of quality available in the exit flow by using the
following equation:


EXPERIMENTAL MASS FLOW RATE, lbm/hr

6.00

08
06
04

02

VISCO JET LOHM RATINGS

243.000 80 000 41.000 17.600

VISCO JET EXIT
CONDITIONS

© SINGLE PHASE

0 TWOPHASE

WM TWO-PHASE PARTIAL
VISCO JET BLOCKAGE

MODIFIED LEE EQUATION = 42.000 JaP=S (1-X)

! rota titil ! n

02

Figure 8. - Experimental and predicted values with modified Lee equation; 17 600, 41 000, 80 000, and 243 000 Lohm's.

04 06.08 10 20 40 60 80 1 2
PREDICTED FLOW RATE WITH MODIFIED LEE EQUATION, lbmv/hr

2.0 —

E

a tS

é

g

3

z

3 to

2

PA

2

= 5

o

Fa

in] MODIFIED _ 10.000 reBE (y -
LEE EQUATION ~ Loum ¥4P *S (1-0)
| i ! J

Cy) 5 1.0 18 20

PREDICTED FLOW RATE WITH MODIFIED LEE EQUATION,
Iomvhr

Figure 9. - Range of experimental and predicted values with
modified Lee equation, 41 000 Lohm's.

21


ht enthalpy total, Btu/lbm

KR Visco Jet outlet indicator: if 1, then saturated outlet; if 2, then
subcooled outlet

Lohm Lohm rating, 1 Lohm = 100 g/min H90 per 25 psid at 80 °F
MDATA measured flow rate, lbm/hr

MLEE calculated flow rate with Lee equation, lbm/hr

MMOD calculated flow rate with modified Lee equation, lbm/hr

m calculated mass flow rate, lbm/hr

PIN inlet pressure to Visco Jet, psia

POUT outlet pressure of Visco Jet, psia

S specific gravity: Visco Jet inlet density, (lbm/ft3)/62.4
TIN inlet temperature to Visco Jet, °R

TOUT outlet temperature of Visco Jet, °R

TSAT saturation temperature at PIN, °R

x quality
x independent parameter in analytical model
AP pressure difference across the Visco Jet, psid

EXPERIMENTAL EQUIPMENT

The Visco Jet Test Apparatus is designed as a test stand mounted on a
wheeled cart to enable a high degree of flexibility within the test program.
It can flow either liquid nitrogen or liquid hydrogen without modification. A
design goal was the minimization of heat leak into the test article to maintain
the flow process as close to isenthalpic as possible.

Flow System

Figure 1 is a system schematic of the Visco Jet Test Stand showing the
mobile 250 gal liquid nitrogen supply dewar connected to the test rig through
a vacuum jacketed fill line. The cylindrical vacuum chamber which houses the
Visco Jet as part of the flow system is 10 in. in diameter with a height of
19 in. The entire rig, including the test chamber and the flow system piping,
is made of stainless steel. The fluid transfer line and the inlet piping to
the test chamber flange are vacuum jacketed. The liquid flow control valve
between the supply dewar and the test chamber is also vacuum jacketed and pneu-
matically actuated. Pressure regulating valves downstream of the flow system


TABLE II. - Continued

(b) 41 000 Lohm

AP MDATA | MMOD | MLEE PIN POUT TIN TOUT TSAT xX KR
54.41 | 1.52 1.54 | 1.64 | 57.51 3.10 | 130.25 | 118.97 | 164.07 | 0.0610 1
50.03 | 1.53 1.57 | 1.57 | 57.53 7.50 | 129.62 | 130.28 | 164.08 -0006 1
43.01 | 1.39 1.46 | 1.46 | 57.55 | 14.54 | 129.02 | 129.46 | 164.09 -0000 2
29.91 | 1.19 1.21 | 1.21 | 57.48 | 27.56 | 130.32 | 130.50 | 164.06 -0000 2
18.31 +95 95 -95 | 57.50 | 39.19 | 130.00 | 130.33 | 164.07 -0000 2
13.70 81 82 -82 | 59.04 | 45.34 | 130.30 | 130.51 | 164.64 -0000 2
14.07 -80 82 -82 | 60.83 | 46.76 | 138.32 | 138.61 | 165.29 -0000 2
23.15 .99 1.05 | 1.05 | 62.38 | 39.22 | 138.48 | 138.62 | 165.84 -0000 2
34.63 | 1.23 1.29 | 1.29 | 62.25 | 27.61 | 138.60 | 138.61 | 165.80 -0000 2
47.98 | 1.44 1.52 | 1.52 | 62.56 | 14.58 | 138.57 | 138.68 | 165.91 .0000 2
56.72 | 1.54 1.56 | 1.65 | 64.07 7.35 | 138.54 | 138.68 | 166.43 -0520 1
58.61 | 1.53 1.50 | 1.68 | 61.76 3.15 | 138.23 | 118.74 | 165.62 +1033 1
55.55 | 1.38 1.35 | 1.61 | 58.57 3.03 | 148.02 118.35 | 164.47 .1576 1
50.14 | 1.31 1.37 | 1.53 | 57.77 7.62 | 148.15 | 129.06 | 164.17 .1024 1
43.65 | 1.26 1.35 | 1.42 | 58.20 | 14.56 | 148.34 | 138.24 | 164.33 -0537 1
30.00 | 1.13 1.18 | 1.18 | 57.47 | 27.46 | 148.03 | 148.31 | 164.06 .0000 2
18.70 91 +93 -93 | 57.22 | 38.52 | 147.96 | 148.40 | 163.96 .0000 2
9.15 -66 -65 -65 | 56.78 | 47.63 | 147.51 | 148.39 | 163.80 -0000 2
55.09 | 1.14 1.18 | 1.56 | 57.97 2.89 | 163.27 | 117.61 | 164.24 -2411 1
50.40 | 1.09 1.21 | 1.49 | 57.92 7.53 | 163.39 | 129.06 | 164.22 -1872 1
42.14 | 1.02 1.18 | 1.36 | 57.10 | 14.96 | 162.91 | 138.61 | 163.92 -1344 1
33.30 | 1.00 1,12 | 1.21 | 60.00 | 26.70 | 162.20 | 148.12 | 164.99 .0784 1
18.78 -76 87 -91 | 59.16 | 40.38 | 163.89 | 155.77 | 164.68 -0441 1
10.51 -68 -66 -68 | 58.25 | 47.74 | 163.61 | 163.64 | 164.35 -0219 1
9.94 -60 -65 .67 | 45.00 | 35.06 | 158.52 | 153.19 | 158.95 -0271 1
15.88 +72 81 -84 | 44.33 | 28.45 | 157.83 | 149.20 | 158.65 .0456 1
29.38 85 1.03 | 1.15 | 44.07 | 14.69 | 157.62 | 138.58 | 158.53 .1054 1
37.21 .89 1.09 | 1.29 | 44.40 7.19 | 157.45 | 128.46 | 158.68 +1571 1
41.04 | 1.01 1.07 | 1.36 | 43.84 2.80 | 157.14 | 117.35 | 158.42 -2097 1
29.54 88 -95 | 1.16 | 32.25 2.71 | 151.60 | 117.12 | 152.50 .1818 1
24.97 81 -94 | 1.07 | 32.49 7.53 | 151.72 129.05 | 152.64 -1223 1
16.49 .70 -81 .87 | 31.10 | 14.61 150.85 | 138.32 151.83 -0671 1
9.43 58 64 -66 | 30.67 | 21.24 | 150.55 | 144.21 | 151.57 -0317 1
4.19 41 +43 -44 | 31.58 | 27.39 | 151.39 | 148.55 | 152.11 -0111 1

14



TABLE II. - Concluded

(d) 243 000 Lohm

AP MDATA | MMOD | MLEE PIN POUT TIN TOUT TSAT xX KR
56.04 | 0.31 0.28 | 0.28 | 59.09 3.05 | 123.30 | 118.44 | 164.66 | 0.0244 1
56.00 129 -28 +28 | 58.98 2,98 | 118.94 | 118.01 | 164.62 -0024 1
49.98 -28 -27 +27 | 57.51 7.53 | 118.07 | 120.08 | 164.07 -0000 2
43 53 -26 +25 +25 | 57.91 | 14.38 | 117.90 | 119.38 | 164.22 .0000 2
31.12 +23 21 -21 | 59.25 | 28.13 | 118.22 | 120.06 | 164.72 -0000 2
17.06 -16 -16 -16 | 58.48 | 41.42 | 119.15 | 121.31 | 164.43 .0000 2
8.04 -12 ell -11 | 57.26 | 49.21 | 119.48 | 122.34 | 163.98 .0000 2
10.88 13 +12 +12 | 58.58 | 47.70 | 138.37 | 138.52 | 164.47 .0000 2
18.64 17 -16 -16 | 57.76 | 39.12 | 138.71 | 139.99 | 164.16 -0000 2
30.75 21 -20 -20 | 58.00 | 27.25 | 138.72 | 140.40 | 164.25 -0000 2
44,18 +25 25 -25 | 58.64 | 14.46 | 138.60 | 139.98 | 164.49 -0000 2
50.87 +27 125 -26 | 58.60 7.73 | 138.23 | 129.06 | 164.48 .0466 1
53.64 +28 25 +27 | 57.65 4.01 | 137.82 | 120.97 | 164.12 -0872 1
56.52 29 25 -28 | 59.46 2.94 | 137.69 | 117.55 | 164.79 +1041 1
56.59 28 +23 +27 | 59.60 3.00 | 148.49 | 117.79 | 164.84 .1607 1
50.85 26 23 +26 | 58.84 7.99 | 150.32 | 129.37 | 164.57 -1111 1
43.72 «24 +23 +24 | 58.11 14.39 | 148.75 | 137.70 | 164.30 -0570 1
31.81 .20 21 +21 | 59.77 | 27.95 | 148.06 | 145.62 | 164.91 ,0000 2
19.97 .17 -16 -16 | 58.26 | 38.29 | 147.58 | 149.02 | 164.35 -0000 2
9.03 11 1 -11 | 58.75 | 49.72 | 150.41 | 148.61 | 164.53 -0000 2
1.90 06 -05 -05 | 58.79 | 56.90 | 148.92 | 150.55 | 164.55 -0000 2
54.53 +26 -20 -26 | 57.45 2.92 | 161.51 | 117.55 | 164.05 +2311 1
51.25 +25 +21 -25 | 58.74 7.49 | 162.28 | 128.64 | 164.53 .1814 1
44.50 24 -20 -24 | 58.89 | 14.39 | 162.38 | 137.71 | 164.58 .1345 1
31.57 -20 18 -20 | 58.80 | 27.23 | 162.64 | 148.10 | 164.55 -0790 1
20.25 15 +15 -16 | 58.48 | 38.23 | 162.55 | 154.35 | 164.43 -0421 1
9.11 12 -11 -11 | 58.74 | 49.63 | 160.75 | 156.90 | 164.53 -0000 2
2.15 -06 -05 -05 | 58.17 | 56.02 | 162.21 | 158.67 | 164.32 -0000 2
43.00 22 -18 :23 | 45.76 2.76 | 157.57 | 117.44 | 159.29 +2128 1
38.69 -21 19 -22 | 46.16 7.46 | 157.69 | 129.04 | 159.47 +1560 1
32.07 19 18 -20 | 46.41 14.34 | 157.84 | 138.23 | 159.58 -1087 1
16.51 13 14 -15 | 46.09 | 29.58 | 157.93 | 150.04 | 159.44 -0421 1
6.20 -10 .09 -09 | 45.80 | 39.60 | 157.51 | 153.22 | 159.31 -0069 1
2.22 -06 05 -05 | 45.82 | 43.60 | 158.21 | 156.22 | 159.32 -0000 2
29.87 19 16 -20 | 32.55 2.69 | 151.54 | 116.90 | 152.67 -1819 1
22.87 16 15 «17 | 30.74 7.87 | 149.94 | 129.54 | 151.61 -1094 1
17.73 14 14 -15 | 32.06 | 14.33 | 150.88 | 138.21 | 152.39 -0689 1
9.93 lL 11 -11 | 31.97 | 22.03 | 150.87 | 144.95 | 152.34 -0301 1
4.70 13 .08 -08 | 30.94 | 26.24 | 150.49 | 147.74 | 151.73 -0103 1
1.26 05 04 -04 | 32.55 | 31.28 | 151.74 | 149.74 | 152.67 -0000 2

16



long as the J-T coefficient for the process is positive. The use of a Visco
Jet to achieve this (J-T) effect for aerospace systems has been proposed

(ref. 1) because of its simplicity. Its primary advantage over a valve is the
absence of moving parts. Its major disadvantage is the decreased flexibility
in the operating flow rates. Visco Jets (ref. 2) were designed as miniature
hydraulic flow components using a "multiple orifice" concept to induce a pres-
sure drop ina line. The flow path includes many orifices in series contain-
ing spin chambers that induce significant pressure drops. This design allows
the use of holes five times larger than a single hole required to produce the
same pressure drop. The larger hole reduces the possibility of clogging due
to solid contaminants in the line. The onset of cavitation is also minimized
by the reduced velocity in the jet due to the larger size hole. The resistance
to flow is measured in liquid ohms - or Lohms, a term created and used by the
manufacturer. This term is included in an equation from reference 2 that pre-
dicts single-phase liquid flow rates for many fluids. The form of the equa-
tion, defined as the Lee equation, follows:

5 (2,22) a0s) 0

The specific gravity term (S) permits the use of this equation for various
types of fluids listed in reference 2. The reference does not list the cryo-
genic fluids. Although the multiple orifice design reduces the onset of cavi-
tation with hydraulic fluids, it is inevitable with cryogens that are stored
at or near saturated conditions. An isenthalpic expansion through a Joule-
Thomson device leads to an end state in the two-phase thermodynamic region.
This cavitation or flashing reduces the flow rate predicted using theory for
single-phase liquid flow. Although the drop in flow rate is anticipated, a
correlation of mass flow rate as a function of pressure drop has not been
developed for cavitating flow.

The objective of the test program described in this report was to build a
test rig capable of obtaining liquid nitrogen and liquid hydrogen flow rate
and pressure drop data across a series of Visco Jets with different resistance
to flow. The data obtained would then be correlated either theoretically or
empirically, in terms of mass flow rate, for a given set of inlet and exit con-
ditions. This report presents the results of the liquid nitrogen study. The
liquid hydrogen data will be forthcoming and when available will be published
in a separate report.

NOMENCLATURE
Op accumulated error in the analytical model due to the errors in all the
independent parameters
Yy experimental error of the independent parameter
F analytical model depending upon several independent parameters
hg enthalpy vapor, Btu/lbm
hy enthalpy liquid, Btu/lbm


£-5449

ACQUISITION AND CORRELATION OF CRYOGENIC NITROGEN MASS FLOW DATA
THROUGH A MULTIPLE ORIFICE JOULE-THOMSON DEVICE

Stephen S. Papell
Analex Corporation
NASA Lewis Research Center
Fairview Park, Ohio 44126

Naseem H. Saiyed and Ted W. Nyland
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135

SUMMARY

Liquid nitrogen mass flow rate, pressure drop, and temperature drop data
have been obtained for a series of multiple orifice Joule-Thomson devices,
known as Visco Jets, over a wide range of flow resistance. The test rig used
to acquire the data was designed to minimize heat transfer so that fluid expan-
sion through the Visco Jets would be isenthalpic. The data include a range of
fluid inlet pressures from 30 to 60 psia, fluid inlet temperatures from 118 to
164 °R, outlet pressures from 2.8 to 55.8 psia, outlet temperatures from 117 to
162 °R, and flow rate from 0.04 to 4.0 lbm/hr of nitrogen.

A flow rate equation supplied by the manufacturer was found to accurately
predict single-phase (noncavitating) liquid nitrogen flow through the Visco
Jets. For cavitating flow, the manufacturer's equation was found to be inaccu-
rate. Greatly improved results were achieved with a modified version of the
single-phase equation. The modification consists of a multiplication factor
to the manufacturer's equation equal to one minus the downstream quality based
on an isenthalpic expansion of the fluid across the Visco Jet. For a range of
flow resistances represented by Visco Jet Lohm ratings between 17 600 to
80 000, 100 percent of the single-phase data and 85 percent of the two-phase
data fall within +10 percent of predicted values.

INTRODUCTION

The need for space-based cryogenic fluids will increase with the escalat-
ing interests of private industry and government in space. Because of this
increasing need and the cost of transporting cryogenic propellants and fluids
to low Earth orbit, the efficient management of these fluids is required. NASA
is tasked with developing technologies enabling the design of efficient systems
for managing subcritical cryogenic fluids in a space environment. Five tech-
nology areas under investigation are liquid storage, supply, transfer, fluid
handling, and advanced instrumentation. One of the storage technologies,
addressed in this report, is pressure control via a thermodynamic vent system
(TVS) that requires a Joule-Thomson (J-T) device to effect the cooling of the
cryogen prior to entering a heat exchanger.

The J-T effect can be achieved via any isenthalpic expansion device such
as an orifice, a regulator, or a needle valve. The expanding fluid cools as


TABLE I. - VISCO JET WATER CALIBRATION TEST RESULTS

Lohn Unit Flow Calculated | Percent
rating rate, Lohm error
lbm/hr
17 600 1 2.948 16 950 -3.70
2 2.672 18 700 6.24
a3 2.864 17 440 -0.88
4 2.896 17 250 -1.98
5 2.908 17 180 -2.38
6 2.938 17 000 -3.38
41 000 1 1,174 42 560 3.80
2 1.160 43 070 5.05
ag 1.218 41 020 0.05
4 1.216 41 090 0.21
5 1.176 42 480 3.60
a6 1.182 42 270 3.10
80 000 1 604 82 640 3.30
2 574 86 960 8.70
a3 610 81 830 2.28
4 .582 85 760 7.21
5 604 82 640 3.30
6 562 88 820 11.00
243 000 1 194 257 500 5.98
2 198 252 300 3.84
3 .198 252 300 3.84
4 -198 252 300 3.84
5 196 254 900 4.90
ag -200 249 800 2.80

a@Data obtained with these Visco Jets.

12


TABLE II. - Continued
(c) 80 000 Lohm

AP MDATA | MMOD | MLEE PIN POUT TIN TOUT TSAT xX KR
58.02 |} 0.85 0.84 | 0.87 | 60.87 2.84 | 124.92 | 117.54 | 165.30 | 0.0372 1
57.18 -87 -86 -87 | 59.95 2.77 | 120.67 | 117.50 | 164.97 -0158 1
52.33 82 -83 -83 | 59.84 7.51 | 120.46 | 121.20 | 164.93 -0000 2
46.39 82 79 .79 | 60.68 | 14.29 | 119.20 | 119.34 | 165.24 -0000 2
32.93 .65 -66 .66 | 60.75 | 27.82 | 121.40 | 121.42 | 165.26 .0000 2
23.95 -56 +57 .57 | 60.79 | 36.84 | 119.09 | 120.09 | 165.28 -0000 2
13.41 +42 +42 .42 | 60.71 | 47.30 | 118.43 | 119.34 | 165.25 .0000 2
12.44 39 -40 -40 | 60.88 | 48.44 | 128.94 | 129.12 | 165.31 -0000 2
23.73 54 55 .55 | 60.91 | 37.18 | 128.75 | 129.43 | 165.32 .0000 2
33.33 64 66 .66 | 60.84 | 27.51 | 128.71 | 129.42 | 165.29 -0000 2
45.97 76 +77 .77 | 60.67 | 14.69 | 128.68 | 129.07 | 165.23 -0000 2
53.43 -80 -83 -83 | 60.89 7.46 | 129.43 | 130.01 | 165.31 -0001 1
58.09 84 .81 .87 | 60.81 2.72 | 130.55 | 131.15 | 165.28 -0699 1
58.08 82 «76 -86 | 60.76 2.68 | 137.84 | 116.90 | 165.27 .1099 1
52.81 +77 -78 -82 | 60.46 7.64 | 138.34 | 129.10 | 165.16 -0481 1
45.88 -68 -76 :76 | 60.30 | 14.42 | 138.56 | 138.23 | 165.10 -0000 2
32.04 -59 64 .64 | 60.56 | 28.51 | 138.60 | 139.16 | 165.19 -0000 2
22.94 “51 54 .54 | 60.53 | 37.59 | 138.60 | 139.29 | 165.18 -0000 2
11.87 +37 .39 .39 | 60.19 | 48.32 | 138.83 | 139.66 | 165.06 -0000 2
56.77 175 +70 -83 | 59.37 2.60 | 146.61 | 116.67 | 164.76 -1581 1
51.78 -69 71 -80 | 59.23 7.45 | 148.09 | 128.98 | 164.71 .1037 1
44,73 -69 .70 .74 | 59.08 | 14.35 | 147.99 | 138.22 | 164.65 .0530 1
29.29 .55 -60 .60 | 60.17 | 30.88 | 148.14 | 148.05 | 165.05 -0000 2
19.39 +45 -49 .49 | 59.67 | 40.28 | 148.16 | 148.93 | 164.87 -0000 2
11.70 36 38 .38 | 59.57 | 47.87 | 147.41 | 149.14 | 164.83 -0000 2
11.47 31 36 .36 | 59.64 | 48.17 | 162.28 | 159.25 | 164.86 -0124 1
20.52 -40 -46 .49 | 59.03 | 38.50 | 163.84 | 154.80 | 164.64 -0493 1
30.58 -48 55 .59 | 58.68 | 28.10 | 163.62 | 148.99 | 164.51 -0817 1
44.39 .59 -62 .72 | 58.83 | 14.44 | 163.20 | 138.20 | 164.56 .1390 1
50.22 61 -62 -76 | 58.20 7.98 | 163.11 | 129.58 | 164.33 -1818 1
55.55 65 -60 -80 | 58.09 2.54 | 163.00 | 116.40 | 164.29 +2459 1
43.62 .59 -56 +72 | 46.12 2.50 | 158.23 | 116.25 | 159.45 +2211 1
38.27 51 57 -67 | 46.00 7.73 | 158.23 | 129.28 | 159.40 .1566 1
31.97 49 154 .61 | 46.31 | 14.34 | 158.55 | 138.19 | 159.53 .1127 1
18.38 39 44 .47 | 45.82 | 27.44 | 157.88 | 148.51 | 159.32 -0496 1

6.49 28 127 .28 | 45.68 | 39.19 | 157.90 | 155.03 | 159.25 -0105 1

6.09 24 127 .27 | 33.78 | 27.68 | 152.32 | 148.84 | 153.36 -0155 1
17.97 -40 45 .47 | 37.18 | 19.22 | 148.51 | 142.54 | 155.19 -0295 1
21.86 43 -48 .62 | 36.29 | 14.43 | 149.74 | 138.23 | 154.72 -0620 1
26.43 -47 -50 .56 | 33.70 7.27 | 151.46 | 128.53 | 153.32 +1233 1
29.56 +49 49 -60 | 32.01 2.44 | 150.96 | 115.81 | 152.36 .1836 1

15