John McQuillen and Brian Motil

Glenn Research Center, Cleveland, Ohio

Reduced Gravity Gas and Liquid Flows:

Simple Data for Complex Problems

NASA/TM—2001-210681

February 2001

AIAA–2001–0324
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Reno, Nevada, January 8–11, 2001

John McQuillen and Brian Motil

Glenn Research Center, Cleveland, Ohio

Reduced Gravity Gas and Liquid Flows:

Simple Data for Complex Problems

NASA/TM—2001-210681 AIAA–2001–0324
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NASA/TM—2001-210681 1 

Reduced Gravity Gas and Liquid Flows: Simple Data for Complex Problems

John McQuillen and Brian Motil 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

Abstract

While there have been many studies for two-phase flow 

through straight cylindrical tubes, more recently, a new 

group of studies have emerged that examine two-phase 

flow through non-straight, non-cylindrical geometries, 

including expansions, contractions, tees, packed beds 

and cyclonic separation devices. Although these studies 

are still, relatively speaking, in their infancy, they have 

provided valuable information regarding the importance 

of the flow momentum, and the existence of liquid 

dryout due to sharp corners in microgravity. 

Introduction

Studies of gas-liquid flows have been conducted by the 

chemical, nuclear and petroleum industries for many 

years. The influence of gravity on gas-liquid flows has 

been demonstrated many times by simply changing the 

orientation of the flow direction with respect to gravity. 

Changes in the flow regime and its characteristics, and 

the pressure drop have been documented for changes as 

little as 0.25° between the gravity vector and the flow 

direction.1

 Reduction in the magnitude of the gravity 

vector will also have a profound effect, not only on the 

gas-liquid flow behavior, but also on the technologies 

that will be required for future space-based platforms. 

The Space Studies Board for the National Research 

Council recently released a report documenting several 

technologies and fundamental science issues regarding 

those technologies.2

 The systems that require these 

technologies include thermal management systems, 

power systems, fluid management, and environmental 

control and life support systems (ECLSS). As such, 

these systems encompass a wide range of fluids from 

cryogens being used for propellant and fuel cells to 

liquid metals for proposed space nuclear power 

systems. These systems will operate in gravity 

environment ranging from a steady-state microgravity 

condition to lunar, Martian or normal gravity to 

transient environments greater than normal gravity such 

as those encountered during large rocket firings. Length 

scales range from micrometer-size holes found in heat 

pipes and those found in some proposed electronic 

cooling schemes to several centimeters in cryogenic 

and adiabatic transfer lines and space radiators. 

Colin, et al.3

 and McQuillen, et al.4 presented a review 

of gas-liquid flow experiments through straight 

cylindrical tubing. Most of these experiments have been 

conducted using multi-component two-phase mixtures 

including air and water, water-glycerin, or watersurfactant mixtures, but there have also been some 

experiments that have used R-12 and R134a as a single 

component, two-phase mixture. Abdollahian, et al.,5

undertook a study of system stability involving both 

critical heat flux and pumped loop instability using 

R-114. These studies were all conducted aboard various 

aircraft flying parabolic trajectories, which can achieve 

about 20 seconds of 0.01 g’s. As such, it should be 

recognized that this method offers only a limited 

amount of time for the low gravity flow regime to 

establish itself and traverse an instrument test section, 

much less a complete system. Additionally, the low 

gravity environment aboard the aircraft is not high 

quality as both weather-induced turbulence and pilot 

skill can have a significant impact. Although several 

space-based experiments have been proposed, length, 

weight, power and data acquisition rate restrictions 

have either severely limited space-based testing or 

prevented it altogether. 

Undoubtedly, while most systems will have straight 

lengths of cylindrical tubing, they will also incorporate 

non-cylindrical or changing geometries such as 

expansions, contraction, tees, valves, etc. This paper 

reports some experiments on gas-liquid flows through 

contractions, expansions, tees, bends, packed beds, and 

a cyclonic separation device. 
NASA/TM—2001-210681 2 

Contractions

McQuillen6

 conducted a series of low gravity 

experiments using air and water as the test fluids of 

flow through contractions. The entry region had a 

diameter of 25.4 mm with an exit diameter of 19.0 or 

12.7 mm. High-speed video imaged the flow while 

conductivity probes were used to measure liquid film 

thickness and void fraction. 

The transition of the flow regimes was rather revealing 

based on the video. As seen in Figure 1, bubble 

coalescence does not occur between axially displaced 

bubbles as the liquid between the bubbles is accelerated 

with the bubbles and then causes the distance between 

the bubbles to increase. Bubbles that are radially 

displaced will sometimes coalesce or may just bounce 

off each other. The primary transition from bubble to 

slug flow occurs when large spherical bubbles are 

radially compressed to fit into the smaller diameter as 

seen in the case of the lead bubble in Figure 1. These 

spherical bubbles must have a radius larger than that of 

the contracted area. 

Another interesting phenomena is that liquid film 

dryout occurred in some cases in the vena contracta 

area of the contraction (Figure 2). Typically, bubbles 

are caught in this recirculation zone and coalesces into 

a larger gas pocket. As this area continues to grow, it 

reaches some size whereby the flow shears the gas 

pocket into two. One pocket remains at the vena 

contracta, but the other pocket is swept downstream. It 

is suspected that the gas pocket is held in place both by 

the low pressure region of the vena contracta and the 

pinning edge of the reduced diameter. 

Taylor bubbles form a liquid bridge across the bubble 

as they entered the contraction. The liquid bridging is 

unstable and collapses downstream as the front part of 

the bubble apparently has a thinner liquid film around 

it, which slows the bubble down relative to its tail 

allowing its tail to catch up and coalesce. If two Taylor 

bubbles enter the test section and the tail of the leading 

bubble is separated from the nose of the trailing bubble 

by less than 1 tube diameter, the liquid between the two 

bubbles drains into the liquid film and the second 

bubble attempts to coalesce with the lead bubble. 

Liquid slugs in general become much thinner at higher 

velocities and as such, gas begins to penetrate the gas 

bubble. Unfortunately, because the field of view was 

relatively short, it was not possible to view the 

complete transition from slug to annular flow. 

Expansions

A series of tests were recently conducted aboard the 

KC-135 to examine the effect of gas-liquid flows into an 

expansion. Air and water, and air and a 50 without waterglycerin mixture were used as the test fluids. The entry 

section had a 12.7 mm diameter tube, and expansions 

with either a diameter of 19.0 or 25.4 mm were tested. 

Instrumentation included conductivity probes to measure 

void fraction and differential pressure transducers. 

A high-speed video imager was used. 

Due to the type of mixer that was used to introduce the 

two phases together, it was not possible to obtain 

annular flow in the entry region, although a broad span 

of tests for bubble and slug flow conditions was 

conducted. Also, the mixer and the insufficient length 

for the flow development, test conditions that should 

have resulted in slug flow, actually caused bubble flow 

as they left the entry section and entered the expansion. 

For both the slug and bubble flow conditions at low 

flow velocities, the flow enters the expanded region and 

Figure 1.—Time Sequence as two bubbles flow 

through a 25.4 to 19 mm contraction. 

Figure 2.—Bubble flow through a 25.4 to 

12.7 mm contraction. The dark band on 

contraction is where the gas is recirculating. 
NASA/TM—2001-210681 3 

readily conforms to the new larger diameter. In the case 

of bubble flow, especially for the larger expansions that 

were tested, there is a recirculation zone of bubbles in 

the cylinder’s corner (Figure 3a). Usually, a large gas 

pocket forms in the corner of the expanded area and 

remains there for a significant portion of the test 

(Figure 3b). For the tests involving water, the gas 

pocket is eventually swept downstream, while for those 

tests with the water-glycerin mixture, the gas pocket 

remains there for duration of the entire test. Regardless, 

this gas pocket alters significantly the flow field behind 

it as bubbles become trapped in its wake. For the water 

tests, multiple gas pockets alternate positions of being 

in the corner and the wake corner pocket. 

At higher flowrates, a two-phase jet develops. The jet 

traverses through the central portion of the tube and is 

surrounded by the gas phase. For an entering bubble 

flow regime, a jet approximately equal to the diameter 

of the entrance section is observed (Figure 3c). The 

mixture of liquid and gas bubbles proceeds down the 

length of the test section. 

If there were any Taylor bubbles present, the situation 

is different. Since these cylindrically shaped bubbles 

are no longer constrained radially by the tube wall, they 

start to expand radially and shrink axially. Figure 4 

illustrates this process. These bubbles separate from the 

preceding, faster-moving liquid slug, thus breaking up 

the two-phase jet. The bubbles then slow down 

significantly and become a spherical shape. The 

spherical lobes can be either overtaken by succeeding 

liquid slugs or grow to the point of contacting the walls 

and rupturing. When a liquid slug contacts the bubble, 

liquid splashes onto the tube wall as the bubble 

ruptures. This behavior is apparently dependent on the 

length of the cylindrical bubble and the slugging 

frequency. 

For very long cylindrical bubbles, the stretching of the 

thin film also causes rupture of the bubble. The motion 

is caused by both the radial expansion and the initial 

pull from the preceding liquid slug before the slug had 

detached. Generally, after the bubble film ruptures, 

there is no additional liquid film motion from the 

entrance into the expansion since the liquid film in the 

entrance has already stopped moving. 

The rupture of the thin film cylindrical bubbles and 

splashing from the liquid slug penetration of these 

bubbles supply the liquid for the quiescent film on the 

wall. The deposition of additional liquid would result 

in some wave motion in the film, but overall, there was 

very little liquid motion within this film. 

Typical flow regime maps are shown in Figures 5 and 6 

for the water and glycerin mixtures for the 12.7 to 19.0 

and 12.7 to 25.4 mm expansions respectively. As was 

discussed earlier, for the slower flowrates, there is no 

change in the flow regime. At faster flowrates, 

however, there is typically the formation of a two-phase 

jet. The transition to jetting from the “traditional” flow 

regimes occurs much more readily for the larger change 

in diameter ratio than the smaller change. It is possible 

that this is due to the closer walls restrict the amount 

that the two-phase jet can expand radially more than the 

case for the larger diameter tubes. In general, the liquid 

flowrate seems to play a significant role in the jet 

formation, probably because of the high liquid density 

and, thus, momentum. 

 (a) 

 (b) 

(c) 

Figure 3.—Bubble flow into an expansion. 

(a) Flow conforms to geometry, (b) Gas 

pocket in corner of expansion, (c) Bubble 

jet in expansion. 

 (a) 

 (b) 

 (c) 

 (d) 

 (e) 

Figure 4.—Slug flow to two-phase jet. (a) Slug 

in entrance, (b) Slug enters empty expansion 

pulling thin film behind it, (c) Slug detaches 

from bubble, (d) Thin film forms spherical 

lobes, (e) Lobe contacts wall and ruptures. 
NASA/TM—2001-210681 4 

Although this “new” two-phase jet flow regime is 

observed immediately downstream of the expansion, a 

more “traditional” flow regime, such as slug or bubble 

flow, was observed further downstream in the vicinity 

of the conductance probes. This is due to in part for the 

slug flow because of the redeposition of liquid from the 

cylindrical bubble onto the wall. 

Redeposition for bubble flow may be due to the jet 

striking the thin wires of the conductance probes and 

spreading/splashing out to the walls, because of the 

discontinuities between the two pieces of tubing that 

mate adjoining pieces of the test section together, or 

fluctuations in the residual gravity level. 

Water & Glycerin,

12.7 -> 19.0 mm Expansion

1.00E-01

1.00E+00

1.00E-01 1.00E+00 1.00E+01

UGS (upstream m/s)

ULS (upstream m/s)

Bubbly In Bubbly Out

Bubbly In Transition

Bubble In Bubble Jet

Slug In Two Phase Jet

Slug In Slug Out

Slug-Bubble In Bubble Out

Transition for Straight Tube

Figure 5.—Flow regime map for water and glycerin mixture and air in a 19.0 to 25.4 mm expansion. 

Water & Glycerin,

12.7 -> 25.4 mm Expansion

1.00E-01

1.00E+00

1.00E-01 1.00E+00 1.00E+01

UGS (upstream m/s)

ULS (upstream m/s)

Bubbly In Bubbly Out

Bubbly In Transition

Bubble In Bubble Jet

Slug In Two Phase Jet

Transition for Straight Tube

Figure 6.—Flow regime map for water and glycerin mixture and air in a 19.0 to 25.4 mm expansion. 
NASA/TM—2001-210681 5 

Tees

Jayawardena and McQuillen7

 conducted a series of 

experiments for two-phase flow through a splitting tee. 

The test section was 1.27 cm in diameter with flow 

entering on the “run” of the tee and exiting through both 

the “run” and the “sidearm branch.” Water and a water 

glycerin mixture were used for the test liquids, while air 

was the gas phase component. Each leg of the tubing that 

tied into the tee was instrumented with a pair of 

conductivity probes and differential pressure transducers. 

Only the flow through the actual tee was imaged. 

The gas and liquid flowrates into the tee were known 

prior to mixing the two phases together. In order to 

satisfy continuity, the flowrates of both phases needed 

to be measured in at least one of the exit legs. The 

decision was made to separate the two phases exiting 

the sidearm branch and measure the flowrates of both 

phases there. The gas phase flowed through a desiccant 

bed that absorbed any excess moisture before entering a 

thermal mass flow meter. Liquid was contained in the 

separator and the liquid level was measured via a sight 

glass on the side of the separator both prior to and after 

the completion of the test. 

The conditions of the operating environment made it 

difficult to obtain a high level of confidence in the 

sidearm flowrates. For the liquid flowrate, liquid 

needed to drain towards the bottom of the separator 

after the aircraft had pulled out of the low gravity 

parabola and prior to the start of setting up for the next 

trajectory. The residual acceleration levels in all three 

directions aboard the aircraft were not conducive for 

“leveling” the sight glass with the separator. These two 

factors coupled with the high experiment operator 

workload did not give confidence in the ability to 

obtain an accurate liquid flowrate. In addition, the 

liquid flowrate was a “batch” flowrate in that it was 

nothing more than the total mass collected during the 

test divided by the length of the test. There were no 

corrections for flow startup and shutdown. 

While the gas flowrate was more reliable, there was a 

problem with obtaining this data as well. It was difficult 

to measure the lower gas flowrate because of the 

volumetric capacity of the separator and the pressure 

loss associated with flow through the desiccant bed and 

flowmeter. These slow air flows took a significant 

amount of time to generate a sufficient pressure to 

overcome the pressure losses and generate a flow 

within the range of the flow meter. 

Despite these problems, several important observations 

are ascertained. First, from the visualization data, such 

as in Figure 7, it is very difficult for the liquid to turn 

the corner and flow down the sidearm: The preferential 

direction is straight. The two-phase flow in the sidearm 

branch is significantly different in terms of velocity and 

(a) (b) (c) 

 

(d) 

(e) 

Figure 7.—Gas-liquid slug flow through a tee. Flow is from bottom to top and right to left in the sidearm branch. 
NASA/TM—2001-210681 6 

structure as compared to both the entry and exit flows 

on the tee’s run as evidenced not only by the video but 

also by the conductivity probe data. This occurs despite 

attempts to vary the flow resistances in the two legs 

with respect to each other via some metering valves that 

were positioned in each exit leg. 

Finally, the last differential pressure drop in both exit 

legs exhibits a “pressure recovery” when compared to 

the pressure drop in the entry leg. This is similar to flow 

through an expansion due to decrease in mass flow rate 

because of an increase in flow area. However, in 

normal gravity, typically, one exit leg shows signs of a 

pressure recovery while the other exit leg incurs a 

pressure loss. 

Packed Beds

To date, three independent experiments for flow through 

packed beds in low gravity have been conducted. In two 

of these studies, the primary objective was to verify 

sufficient mass transfer, so instrumentation specific to 

hydrodynamics was minimal. 

One of these two, conducted by NASA MSFC, was the 

Volatile Removal Assembly Flight Experiment8

(VRAFE), which flew on STS-89 and STS-96. It was a 

high temperature catalytic oxidation process that 

included several major components, one of which was a 

packed bed reactor. They reported some unexpected 

overall pressure fluctuations, possible gas inclusion in 

the bed and a loss of chemical performance. 

Unfortunately, there was not sufficient instrumentation 

to fully understand the impacts of the microgravity 

environment. 

The other mass transfer study was conducted aboard the 

KC-135 by NASA JSC, which was a waste-water 

bioreactor. This effort utilized a packed bed design 

consisting of Berl saddles packing with Raschig Rings, 

either spiraled through the packed bed or as alternating 

layers of the two packing materials. 

The packed bed was oriented horizontally. Flow was 

continuous throughout the low and high gravity portions 

of the trajectory, but because of the orientation of the 

flow through the packed bed with respected to gravity, 

the flow was diverted to a parallel channel during the 

normal and high g portions of the trajectory. As the 

experiment would enter the low gravity period, water 

that had drained into the bottom of the packed bed was 

wicked throughout the dry area of the packed bed. 

A bubble flow was injected into the packed bed. 

However, due to the volume of the packed bed and the 

initial distribution of the liquid and gas, there was an 

initial surge of gas at the outlet followed by a long slug 

that was almost entirely liquid. Sometimes towards the 

end of the trajectory, a bubbly flow would exit, 

although the void fraction of the exiting flow was lower 

than the entering flow, indicating the flow was not fully 

developed. The bed showed signs of about 30% 

occlusion and a significant amount of flow channeling. 

To address the hydrodynamic issues from the first two 

studies and to better understand the flow characteristics 

of this type of system, Motil et al.9

 used a packed bed 

consisting of spherical glass beads with diameters of 

2 mm and 5 mm. The test apparatus was designed to fly 

on the KC-135 aircraft with the section oriented 

vertically and instrumented with five differential 

pressure transducers evenly spaced along its length. Hispeed video was also used to confirm the flow 

characteristics. The gas and liquid phases were mixed 

prior to the inlet of the column. Water-glycerin 

mixtures ranging from 1 to 20 cP were used and the 

flow rates were varied over a wide range to observe 

bubbly, spray (or mist) and pulse flow. 

The flow pattern transition data indicates that the pulse 

flow regime exists over a much wider range of gas and 

liquid flow rates under microgravity conditions 

compared to normal gravity cocurrent down-flow. 

Figure 8 illustrates this with a widely used flow regime 

map first proposed by Talmor.10 The basis for the 

Talmor map is that a driving-to-resistance force ratio 

can be developed for two-phase flow through a packed 

bed. The driving forces are inertia and gravity while the 

resistance forces are viscous and surface tension. By 

normalizing these forces and using two-phase 

dimensionless numbers, he plots the force ratio versus 

the superficial volumetric gas-to-liquid ratio. By setting 

the gravity term (1/Fr) equal to zero, the plot should 

predict microgravity flow regime transitions, but in 

fact, the bubbly pulse transition is almost an order of 

magnitude lower as indicated by the solid lines. 

The characteristics of the bubbly flow regime are 

similar in 1-g and 0-g except that the overall pressure 

drop across the column is higher in microgravity. The 

increased pressure drop is equivalent to the static head. 

However, it is found that in the pulse flow regime, 

gravity affects both the pressure amplitude as well as 

the overall pressure drop. Finally, in the spray or mist 

flow regime, there is essentially no difference between 

normal and reduced gravity. This is expected since the 

flow regime characterized by very high gas flow rates 

with small droplets of water dispersed throughout the 

packing and is dominated by inertia forces. 
NASA/TM—2001-210681 7 

Cyclonic Separator

Shoemaker and Schrage11 conducted both an 

experimental and analytical effort in the development 

of a passive, free-vortex, or cyclonic separator. Various 

separator configurations were designed and tested using 

air and water and a 50w/o water-glycerin mixture. The 

concept is to inject a two-phase flow tangentially into a 

cylinder and let the flow momentum separate the gas 

and liquid phases into the inner and outer regions of the 

separator respectively. 

Four flow patterns are observed. Bubbly core flow, see 

Figure 9, consists of bubbles flowing in a coaxially 

cyclonic fashion towards the center while the liquid is 

centrifuged out towards the side and occurs during 

moderate inlet velocities. A core flow, similar to 

Figure 10 consists of a nearly cylindrically-shaped gas 

core with a mixture of very small bubbles and liquid 

flowing around the central gas core and is usually 

achieved at high inlet velocities like those occurring 

during annular flow. Transitional flow involves a 

tighter rotation or nearly-cylindrical shaped 

agglomeration of bubbles; however, because of limited 

velocities, there is insufficient bubble coalescence. At 

low flowrates, the separator volume is too large to 

provide sufficient centrifugal action to achieve a decent 

separation and results in an amorphous mess. This last 

flow condition is easily remedied by reducing the 

volume of the separator. 

Summary

Several experiments have been conducted for twophase flow in microgravity through non-straight, noncylindrical geometries. Flow through contractions 

illustrates that the primary driver for a flow regime 

transition from slug to annular flow is not coalescence 

but squeezing large spherical bubbles into smaller 

diameter tubes whereby they become cylindrical 

bubbles. Flow through expansions demonstrates the 

existence of conditions whereby a two-phase jet can 

Figure 9.—Bubbly 

core. 

Figure 10.—Core 

flow.

0.1

1

10

100

Superficial Volumetric Gas / Liquid = (G/L) (ρ /

l ρg)ave

0.1 1 10 100 1000

Driving Forces / Resistance Forces = [1+ 1/Fr]/[We+(1/Re)]

Bubbly Flow

 Pulse Flow

Upper and Lower Boundary

for Bubbly/Pulse Flow Predicted

by Talmor

Upper and Lower Boundary 

Observed for Bubbly/Pulse Flow

in Microgravity

Figure 8.—Microgravity flow regime map for gas-liquid flow through a packed bed. 
NASA/TM—2001-210681 8 

exist that is surround by a gas area. A somewhat 

quiescent liquid film is on the wall except for 

occasional interactions with the two-phase jet’s 

unstable nature. Flow through splitting tees illustrates 

the dominance of the liquid momentum in determining 

the distribution of the phases between the two exits. 

Differences in flow regimes and pressure fluctuations 

are identified for flow though packed beds when 

compared to microgravity. Cyclonic separation devices 

show that the flow momentum can be sufficient to 

passively drive at least a first stage separation of the 

phases. 

 Although these studies are still, relatively speaking, in 

their infancy, they have provided valuable information 

regarding the importance of the flow momentum, and 

the existence of liquid dryout due to sharp corners in 

microgravity. 

References

 

1

 Barnea, D., "A Unified Model for Predicting FlowPattern Transitions for the Whole Range of Pipe 

Inclinations," International Journal of Multiphase 

Flow, 13, No. 1, pp. 1–12, 1987. 2

 Committee on Microgravity Research Space 

Studies Board, National Research Council, 

Microgravity Research in Support of Technologies 

for the Human Exploration and Development of 

Space and Planetary Bodies, National Academy 

Press, 2000. 3

 Colin, C., Fabre, J., and McQuillen, J., “Bubble 

and Slug Flow at Microgravity Conditions: State of 

Knowledge and Open Questions,” Chem. Eng. 

Comm, 141–142, 155–173 (1996). 

 

4

 McQuillen, J.B., Colin, C., and Fabre, J., “GroundBased Gas-Liquid Flow Research In Microgravity 

Conditions: State Of Knowledge” Space Forum, 3, 

165–203, (1998). 5

 Abdollahian, D., Quintal, J., Barez, F., Zahm, J., 

and Lohr, V., “Study of Critical Heat Flux and 

Two-Phase Pressure Drop Under Reduced 

Gravity,” NASA Contractor Report 198516, 1996. 6

 McQuillen, J., “Observations of Gas-Liquid Flows 

Through Contractions in Microgravity,” Third 

Microgravity Fluid Physics Conference, NASA 

Conference Publication 3338, 95–102, 1996. 7

 Jayawardena, S.S. and McQuillen, J.B., 

“Microgravity Two-Phase Flow at a Pipe 

Junction,” AIAA 96–2070, 1996. 8

 Holder, D.W. and Parker, D.S., “Volatile Removal 

Assembly flight Experiment and KC-135 Packed 

Bed Experiment: Results and Lessons Learned,”

30th International conference on Environmental 

Systems, SAE# 2000–01–2251, 2000. 9

 Motil, B.J., Balakotaiah, V., and Kamotani, Y., 

“Effects of Gravity on Cocurrent Two-Phase GasLiquid Flows Through Packed Bed Columns,”

AIAA–2000–0767, 2000. 10 Talmor, E., “Two-Phase Downflow Through 

Catalyst Beds,” AIChE J., 23, No. 6, pp. 868–878, 

1977. 11 Shoemaker, J.M. and Schrage, D.S., “Microgravity 

Fluid Separation Physics: Experimental and 

Analytical Results,” AIAA 97–0886, 1997. 
This publication is available from the NASA Center for AeroSpace Information, 301–621–0390.

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Unclassified Unclassified

Technical Memorandum

Unclassified

National Aeronautics and Space Administration

John H. Glenn Research Center at Lewis Field

Cleveland, Ohio 44135–3191

1. AGENCY USE ONLY (Leave blank)

10. SPONSORING/MONITORING

 AGENCY REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546–0001

Available electronically at http://gltrs.grc.nasa.gov/GLTRS

February 2001

NASA TM—2001-210681

AIAA–2001–0324

E–12608

WU–101–53–00–00

14

A03

Reduced Gravity Gas and Liquid Flows: Simple Data for Complex Problems

John McQuillen and Brian Motil

Two-phase flow; Microgravity; Fittings

Unclassified -Unlimited

Subject Category: 34 Distribution: Nonstandard

Prepared for the 39th Aerospace Sciences Meeting and Exhibit sponsored by the American Institute of Aeronautics and

Astronautics, Reno, Nevada, January 8–11, 2001. Responsible person, John McQuillen, organization code 6712,

216–433–2876.

While there have been many studies for two-phase flow through straight cylindrical tubes, more recently, a new group

of studies have emerged that examine two-phase flow through nonstraight, noncylindrical geometries, including

expansions, contractions, tees, packed beds and cyclonic separation devices. Although these studies are still, relatively

speaking, in their infancy, they have provided valuable information regarding the importance of the flow momentum,

and the existence of liquid dryout due to sharp corners in microgravity.