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i

NASA/TM—2014–217501

Multiphysics Modeling of an Annular Linear

Induction Pump With Applications to Space

Nuclear Power Systems

J. Kilbane and K.A. Polzin

Marshall Space Flight Center, Huntsville, Alabama

March 2014

National Aeronautics and

Space Administration

Marshall Space Flight Center • Huntsville, Alabama 35812
ii

Available from:

NASA STI Information Desk

Mail Stop 148

NASA Langley Research Center

Hampton, VA 23681–2199, USA

757–864–9658

This report is also available in electronic form at

<http://www.sti.nasa.gov>

Acknowledgments

The authors wish to thank Walter Frei from COMSOL for providing very helpful technical support. Additionally, 

the authors want to thank Jim Knox of Marshall Space Flight Center (MSFC) for working to address COMSOL license 

server issues. Continuing management support of this work by Jim Martin and J. Boise Pearson is appreciated, as well 

as the technical editing help provided by Anita Beatty during the assembly of this Technical Memorandum. J. Kilbane 

was supported through the Summer 2013 MSFC Propulsion Academy program.

TRADEMARKS

Trade names and trademarks are used in this report for identification only. This usage does not constitute an official

endorsement, either expressed or implied, by the National Aeronautics and Space Administration.
iii

TABLE OF CONTENTS

1. INTRODUCTION ............................................................................................................. 1

2. REVIEW OF ANNULAR LINEAR INDUCTION PUMP EXPERIMENTAL 

TESTING ........................................................................................................................... 2

3. MULTIPHYSICS MODEL ................................................................................................ 5

3.1 Domain ........................................................................................................................ 5

3.2 Coils ............................................................................................................................. 6

3.3 Stator ............................................................................................................................ 7

3.4 Material Properties ....................................................................................................... 7

3.5 Governing Equations .................................................................................................... 8

3.6 Boundary Conditions ................................................................................................... 8

3.7 Other COMSOL Settings .............................................................................................. 9

4. MODEL RESULTS ............................................................................................................ 10

4.1 Axially-Traveling Magnetic Wave .................................................................................. 10

4.2 Efficiency Curves .......................................................................................................... 11

4.3 Transient Startup .......................................................................................................... 12

5. CONCLUSIONS ................................................................................................................ 13

APPENDIX—HIPERCO 50 B-H DATA ................................................................................ 14

REFERENCES ....................................................................................................................... 15
iv

LIST OF FIGURES

1. Schematic of the ALIP test circuit configured for TDU ALIP testing ....................... 1

2. Example efficiency (with error bars) as a function of flow rate and constant

pump voltage for NaK at a temperature of 325 oC and pump frequency

of 36 Hz (repeated from ref. 5) .................................................................................. 3

3. Models: (a) Three-dimensional CAD model of the ALIP tested in reference 5

and (b) cut-away model of the ALIP tested in reference 6; illustrations taken 

from reference 8 ......................................................................................................... 4

4. Schematic showing the physical layout of the COMSOL model of ALIP ................. 5

5. Configurations: (a) Electrical coil configuration and (b) effective phase 

configuration for the coils in the ALIP ...................................................................... 6

6. Radial magnetic field Br as a function of axial position within the pump

obtained from (a) the computational COMSOL model and (b) experimental

measurements presented in reference 5 (measurements obtained when 

the annulus was evacuated of NaK) .......................................................................... 10

7. Comparison of (a) modeled and (b) experimental pump efficiency curves

for the ALIP of reference 5, operating at three different NaK temperatures

(as indicated) with a peak AC voltage of 120 V and frequency of 36 Hz ................... 11

8. Average calculated velocity of the NaK as a function of time during a startup

transient .................................................................................................................... 12

9. Hiperco 50 B-H curve data (taken for material strips with a heat treatment

of 871 oC (1,600 oF)) ................................................................................................. 14
v

LIST OF TABLES

1. Material properties and associated domains used in the ALIP model ....................... 8
vi

LIST OF ACRONYMS AND SYMBOLS

AC alternating current

ALIP annular linear induction pump

ATC ALIP test circuit

CFD computational fluid dynamics

DC direct current

EMF electromotive force

FSP fission surface power

MTCD multiturn coil domain

NaK sodium-potassium

TDU technology demonstration unit

TM Technical Memorandum
vii

NOMENCLATURE

B magnetic field density

Br radial component of magnetic field density

H magnetic field strength

PIN electrical input power

V voltage

Dp increase in pressure across the pump

d skin depth

η pump efficiency

m magnetic permeability

v volumetric flow rate

s electrical conductivity

w angular frequency of current
viii
1

TECHNICAL MEMORANDUM

MULTIPHYSICS MODELING OF AN ANNULAR LINEAR INDUCTION PUMP 

WITH APPLICATIONS TO SPACE NUCLEAR POWER SYSTEMS

1. INTRODUCTION

Fission surface power (FSP) systems, which are capable of providing consistent performance at any location, could be used to generate power on the surface of the Moon, Mars, other 

planets and moons of our solar system, or on various near-Earth objects. This includes those areas 

near planetary poles or in other permanently shaded regions, offering the capability to provide ondemand power at any time, even at long distances from the Sun. Fission-based systems also offer 

the potential for outposts, crew, and science instruments to operate in a power-rich environment 

while maintaining a relatively small footprint for the reactor system. NASA has been exploring 

technologies with the goal of reducing the cost and technical risk of employing FSP systems. A reference 40-kWe option has been devised that is cost competitive with alternatives while providing 

more power for less mass anywhere on the lunar surface.1–4 The reference FSP system is also readily 

extensible for use on Mars. On Mars, the system would be capable of operating through global dust 

storms and providing year-round power at any Martian latitude. 

One key technology associated with the reference FSP system is the pump that circulates 

liquid-metal coolant through the reactor system. The pump must be compatible with the liquid 

sodium-potassium (NaK) coolant and have adequate performance to enable a viable flight system. 

Presently, this task is accomplished in the reference design using an annular linear induction pump 

(ALIP), which circulates the reactor coolant without the use of moving components. Two separate pumps were recently fabricated and shipped to NASA Marshall Space Flight Center where 

they were tested in a dedicated apparatus designed to quantify pump performance (the ALIP test 

circuit, or ATC). Pump efficiencies in these tests were in the 5%–6% range,5,6 underperforming 

expectations. An effort has been initiated to develop a flexible multiphysics model that accurately 

represents an ALIP to provide a better understanding of the performance scaling and develop 

design strategies that can help increase performance in later iterations. This Technical Memorandum (TM) provides a present view of the state of this modeling effort. For the sake of completeness, note that a similar multiphysics ALIP modeling effort was recently presented by Goldsteins 

et al.7 and general ALIP design optimization work has been presented by Maidana et al.8
2

2. REVIEW OF ANNULAR LINEAR INDUCTION PUMP EXPERIMENTAL TESTING

The ATC apparatus, shown schematically in figure 1, was fabricated to allow for performance testing of liquid-metal induction pumps. The system and testing results are described in 

detail in references 5 and 6. The pressure produced by the pump (Dp) is measured using two absolute pressure transducers located at the downstream and upstream ends of the pump, while the 

volumetric flow rate ( v ) is measured using a calibrated liquid-metal electromagnetic flowmeter. 

A wattmeter provides a measure of the real input power to the pump (PIN), permitting the calculation of pump efficiency as

η = (vΔp) / PIN . (1)

Accumulator

ALIP

Heat Exchanger

Throttling

Valve

Immersion Heaters

Electromagnetic

Flowmeter

Flow Direction

Pump Pressure (∆p)

Flow Direction

Figure 1. Schematic of the ALIP test circuit configured for TDU ALIP testing. F1_1426
3

A plot of pump efficiency as a function of volumetric flow rate, like that shown in figure 2, 

will exhibit an optimum in efficiency when operating at a constant power (constant power and 

constant applied voltage are approximately equivalent in an ALIP). This is easily understood in the 

context of equation (1) and simple concepts of continuity for a closed-loop system. For the bounding case of infinite flow impedance, there is a maximum Dp but v is zero, while in the case of no flow 

impedance in the loop, there is a maximum v but zero pressure rise across the pump.

0 1 2 3 4 5 6

0 20 40 60 80 100

8

6

4

2

0

Flow Rate (L/s)

Flow Rate (gpm)

Efficiency (%)

5 V

20 30 40 50 60 70 80 100

120

110

F2_1426 Figure 2. Example efficiency (with error bars) as a function of flow rate and 

constant pump voltage for NaK at a temperature of 325 oC and pump 

frequency of 36 Hz (repeated from ref. 5).

Three-dimensional renderings of two separate ALIP pumps that were tested in the ATC 

are shown in figure 3. The FSP pump in figure 3(a) was designed for the full-scale 200 kWt, 40 kWe

fission surface power reference design. The technology demonstration unit (TDU) pump in figure 3(b) was fabricated to support the testing of a TDU, which is a one-quarter scale system (50 kWt

, 

10 kWe) that uses simulated nuclear power to achieve an end-to-end demonstration. In general, an 

ALIP consists of an annular duct surrounded by a series of solenoidal copper coils positioned inside 

magnetically-permeable stators elements. An additional magnetically-permeable component is the 

torpedo, which forms the inner boundary of the annular duct. Three-phase power is applied to the 

coils, producing an axially-traveling magnetic wave inside the annulus. The high permeability stators concentrate and direct the magnetic field created by the coils radially across the annulus while 

the torpedo provides the return path for magnetic flux. The axially-traveling radial field induces 

azimuthal currents in the conducting liquid metal that interact with the magnetic field to yield a net 

Lorentz body force in the axial direction, pumping the fluid.
4

(a)

(b)

Torpedo

(Inner Core)

Solenoidal

Coils

Stator

End Shell

(Convoluted for

Thermal Expansion)

Duct

Author: Carl Baily

Torpedo

(Inner Core)

Solenoidal

Coils

Stators

F3_1426

Figure 3. Models: (a) Three-dimensional CAD model of the ALIP tested 

in reference 5 and (b) cut-away model of the ALIP tested in 

reference 6; illustrations taken from reference 8. 

ALIP experimental data for tests conducted with two separate pumps are found in references 5 and 6. As expected, when efficiency is graphed as a function of volumetric flow rate, these 

data exhibit an optimum. Other key findings were that the efficiency curves were generally reduced 

for both higher temperature and at lower power. It was shown that there exists an optimum frequency at which the efficiency of the pump is maximized. This corresponds to the frequency that 

establishes a traveling magnetic wave velocity that is most conducive to transferring power from 

the electromagnetic field into the fluid (also known as the condition of minimal ‘slip’). The present 

computational effort aims to produce a model that can replicate these observed phenomena.
5

3. MULTIPHYSICS MODEL

The ALIP tested in reference 5 was modeled using the commercially available COMSOL 

Multiphysics version 4.3b. The electromagnetics problem was modeled using the alternating current (AC)/direct current (DC) module while the fluid problem was performed using the computational fluid dynamics (CFD) module. Models were developed separately for each component of 

the pump, with simplifying assumptions employed to produce an approximate model that could 

qualitatively reproduce experimental results without requiring intense detailed modeling of any element in the system. The various component models and applied physical properties and boundary 

conditions are discussed in sections 3.1 through 3.7. 

3.1 Domain

The ALIP physical model, shown in figure 4, is representative of the full-sized test apparatus. The model is two-dimensional and axisymmetric, implying no azimuthal variation. For simplicity, the steel casing around the stator and the steel walls of the torpedo were not included in 

the model. Additionally, the curved, aerodynamic profiles of the front and rear of the torpedo were 

simplified as conical shaped. The infinite element feature of the program was used for the outermost domain to mathematically simulate a domain that extends indefinitely without the need of 

unnecessary mesh points. 

Coil 1 (of 12) Stator

NaK Hiperco Flux Return Air/Vacuum

C L

96.5 cm (38 in)

19.1 cm (7.5 in)

F4_1426

Figure 4. Schematic showing the physical layout of the COMSOL model of ALIP.
6

3.2 Coils

The ALIP coils were modeled using the multiturn coil domain (MTCD) feature, which 

implements a homogenized model of a coil using a specified number of wire turns and the crosssectional area of the wires. The wires used in the experimental ALIP were ribbon-like in shape, 

measuring 510 mm × 13.6 mm (0.020 × 0.535 in), and were wound 85 times for each coil. The 

MTCD feature is good for modeling coils with wire diameters that are less than the skin depth 

of the wire, which is defined as

δ = 2 / (ωμσ ) , (2)

where w is the angular frequency of the current, m is the magnetic permeability of the material, 

and s is the electrical conductivity. Using the maximum tested operating frequency of 60 Hz, 

m=4p×107 H/m, and s=6×107 S/m for copper, the value for the skin depth was calculated to 

be roughly 8.4 mm (0.33 in). This is significantly larger than the thickness of a single turn of the 

conductors in the coils, meeting the MTCD sizing requirement. However, while the MTCD feature 

was used in this particular model, investigation to gain a more complete understanding of this feature’s limitations as it applies to ALIP modeling could be a useful avenue of study in future work. 

(For example, while the depth of one coil winding is 510 mm, the total depth of all 85 turns is over 

43 mm and may represent a problem for the MTCD feature.)

The coil domains are further constrained using the Global Equations feature to correctly 

implement the physical coil configuration of the ALIP (see fig. 5(a)). The Global Equations constraints ensure that the total voltage drop across each leg of the delta configuration sums to the 

appropriate applied voltage. This yields the effective phase angles for each set of windings based 

upon the wiring of the pump, as shown in figure 5(b). The coils were assigned the material properties of copper from the COMSOL material database. 

C1 C2 C8 C7

C5

C6

C11

C12

C9

C10

C3

C4

CW

CCW

A

(a)

C

B

Electrical Coil Configuration

VAB = Vmax 0°

VBC = Vmax 120°

VCA = Vmax 240°

C1

C10C11C12

C2C3C4C5C6C7C8C9

0o 120o 240o 300o 180o 60o

Effective Phase Angles

(b)

Figure 5. Configurations: (a) Electrical coil configuration and (b) effective phase configuration F5_1426

for the coils in the ALIP. 
7

3.3 Stator

The stator is one of the few components of the ALIP that has significant azimuthal variation. In the tested ALIP, the stators are constructed as six separate finite sections positioned at 

regular azimuthal intervals around the axis (see fig. 3(a)). Each stator section consists of alternating azimuthal layers (laminates) of steel and an alloy that is itself comprised of 50% Hiperco® 50 

and 50% cobalt iron alloy. The alternating azimuthal laminations and the fabrication of the stators 

as six discreet sections serve to minimize induced circumferential eddy currents. The high magnetic 

permeability of the stator laminations serve to guide and concentrate the magnetic flux radially 

into the fluid. As a simplification, and to establish an upper limit on performance, the stator was 

modeled entirely as Hiperco 50 with zero electrical conductivity, yielding the best magnetic properties while completely suppressing eddy current losses. Future work aimed at understanding how to 

better model the properties of the three-dimensional stator configuration within a two-dimensional 

axisymmetric framework could be a useful path to increase the accuracy of the work discussed in 

this TM.

3.4 Material Properties

The material properties used in the ALIP model are presented in table 1. Included in this 

table are the associated model domains occupied by each type of material listed. The material 

properties for copper and air were obtained from the COMSOL program material libraries and 

the Hiperco 50 values were obtained from the manufacturer, Carpenter Technology Corporation, 

Reading, PA. The nonlinear B-H curve for Hiperco 50 is provided in the appendix. Two entries are 

listed for Hiperco 50, one with finite electrical conductivity for the flux return in the torpedo, where 

eddy currents are permitted, and the other with zero conductivity for the stators. This follows from 

the previous discussion of stator simplification. The material properties of NaK (specifically the 

eutectic NaK-78 mixture) are summarized in reference 9. The present work only considered an 

ALIP operating at room temperature conditions (roughly 20 °C, with the corresponding properties for that temperature given in table 1). However, NaK material property curves in reference 9 

are  given as a function of temperature over the entire ALIP operating envelope (room temperature 

to roughly 525 °C). 
8

Table 1. Material properties and associated domains used in the ALIP model. 

Electromagnetic Properties

Material

Electrical

Conductivity

(S/m)

Relative

Magnetic

Permeability

Relative

Electrical

Permittivity Domain

Copper 6.0×107 1 1 Coils

Hiperco 50 

(with conductivity)

2.5×106 Nonlinear B vs H curve 

(in the appendix)

1 Flux return

Hiperco 50 

(no conductivity)

0 Nonlinear B vs H curve 

(in the appendix)

1 Stator

NaK-78 (at 20 °C) 2.38×106

(from ref. 9)

1 1 Fluid

Hydrodynamic Properties (From Ref. 9)

Material 

Density

(kg/m3)

Kinematic

Viscosity

(Pa-s)

Thermal

Conductivity

(J/kg-K) Domain

NaK-78 (at 20 °C) 875 575 950 Fluid

3.5 Governing Equations

The COMSOL model solves Maxwell’s equations within the AC/DC module over all 

domains while the incompressible, laminar flow, Navier-Stokes equations within the CFD flow 

solver module are solved within the fluid domain. The fluid equations are affected by the Lorentz 

body force that arises from the interaction of eddy currents in the flow and the externally-applied 

magnetic field. The motion of an electrically conductive fluid through a magnetic field also induces 

a back-electromotive force (EMF) that affects the electromagnetic solution of the problem. 

The governing equations are solved using nonlinear segregated solvers, one for each type of 

problem (electromagnetics and CFD), with Maxwell’s equations solved first in the solution process. 

After this first solution is generated, the model can be solved in time to yield a time-dependent 

solution of the problem. The model can also be constructed to use a version of Maxwell’s equations that assume a cyclic solution. This latter, simplified version of the equation set, also referred 

to in COMSOL as frequency domain equations, do not permit the incorporation of nonlinear 

material properties into the model. However, this method can be useful in the initial development 

and implementation of new model features. 

3.6 Boundary Conditions

The fluid domain has no-slip boundary conditions applied to all wall boundaries. A conservation of mass condition is applied to the inlet and outlet of the pump model domain such that the 

total fluid mass in the domain is conserved. The value of the pressure is pinned to a specified value 

at one point within the domain and the pressure drop is specified using a periodic flow boundary 

condition. This allows the user to specify the pressure drop that would occur through the rest of 

the system as fluid flows through it. In the calculations performed to date, the pressure was pinned 

to zero at a single corner point in the model. In future work, this can be pinned to values that are 

close to the measured static pressure in the model. An alternative problem formulation would be 
9

to construct a two-dimensional axisymmetric model representing the length of the entire flow loop, 

where for self-consistency, the pressure at the flow outlet and flow inlet of the simulation domain 

are equal. It is assumed that there is no magnetic flux out of the computational domain (no flux/

zero magnetic potential), with an axis of symmetry condition applied at the centerline. 

3.7 Other COMSOL Settings

Many other settings in COMSOL are changed from their default values to achieve convergence. The fluid elements are set to have second-order discretization and the ‘consistent stabilization’ (numerical dissipation) option was set to ‘streamline diffusion.’ For the time-dependent 

solver, the option to exclude algebraic errors from the error estimation was enabled to prevent the 

inclusion of time-independent errors from the continuity equation. Linear vector elements are used 

to discretize the magnetic vector potential. This selection can be increased to quadratic elements 

(recommended) for a more accurate solution to the magnetic field. The Jacobian update option is 

set so it occurs after every iteration of the electromagnetic solver. 
10

4. MODEL RESULTS

4.1 Axially-Traveling Magnetic Wave

Snapshots of the radial component of the magnetic field located at the midpoint of the 

annulus as a function of axial location are presented in figure 6. The magnetic field output by the 

model is presented in figure 6(a) while measured field values taken from reference 5 are given in 

figure 6(b). The numerical data were obtained from one time-step of a time-varying solution. These 

data were generated for the case where convecting NaK was in the annulus. The experimentallyacquired data, on the other hand, was obtained at ambient conditions with air filling the annulus. 

The measurements were performed using a Hall probe that was inserted into the annulus at various 

axial stations. The model inputs were matched to those used during the experimental measurements 

and the model was solved using the nonlinear Hiperco 50 properties for the flux return and stators. In these figures, the magnetic wave travels from left to right. The inclusion of NaK within the 

domain, with its associated Lorentz body force and back EMF, makes it difficult to quantitatively 

compare these data. In addition, the assumptions that the stator (a) is continuous in the azimuthal 

direction but permits no flowing circumferential eddy currents and (b) is comprised completely of 

Hiperco 50, serve to significantly overestimate the calculated radial magnetic field values. While the 

absolute values of the two curves do not match, likely owing to all the simplifications in the present model, a qualitative comparison between the shapes of the two data sets shows good agreement 

and suggests that the coil configuration given in figure 5 was correctly implemented in the model.

4,000

2,000

0

–2,000

–4,000

Br (G)

Br (G)

0 10 20 30 40

Axial Position (cm)

50 0 10 20 30 40

Axial Position (cm)

50

1,000

750

500

250

F6_1426

0

–250

–500

–750

–1,000

COSMOL Calculated Measured

(a) (b)

Figure 6. Radial magnetic field Br as a function of axial position within the pump obtained 

from (a) the computational COMSOL model and (b) experimental measurements 

presented in reference 5 (measurements obtained when the annulus was evacuated 

of NaK).
11

4.2 Efficiency Curves

A comparison of the pump efficiency as a function of flow rate calculated using the model 

and experimentally measured and documented in reference 5 are presented in figure 7. The model 

curve was generated using the frequency domain equations with linear material properties and is 

therefore not quantitatively comparable to the experimental data since the Hiperco 50 could not 

experience saturation and because the model was solved at 20 °C where the kinematic viscosity 

was unrealistically high. Regardless, the existence of a peak in efficiency is promising in terms of 

providing a check that the physics currently implemented into the model are qualitatively behaving 

as expected.

5

4

3

2

1

0

6

5

4

3

2

1

0

Efficiency (%)

Efficiency (%)

0 0 1 2 3 4 5 6

F7_1426

0.5 1 1.5 2 2.5

Flow Rate (L/s) Flow Rate (L/s)

COSMOL Calculated Measured 325 °C

525 °C

425 °C

(a) (b)

Figure 7. Comparison of (a) modeled and (b) experimental pump efficiency curves for the 

ALIP of reference 5, operating at three different NaK temperatures (as indicated) 

with a peak AC voltage of 120 V and frequency of 36 Hz.
12

4.3 Transient Startup

The average velocity of the fluid as a function of time during a startup transient is presented 

in figure 8. These data were generated as part of a simplified test case to explore the usage of the 

model’s fully nonlinear, time-dependent solution package. For this case, the pressure at the inlet 

and exit of the pump were set equal to each other (minimal pump flow impedance). The model 

was not solved for a long enough time to obtain a steady-state solution, but the solution does 

appear to be approaching an asymptote. This simulation shows that a fully time-dependent, fully 

nonlinear solution can be generated for the problem and geometry of interest.

2

1.5

1

0.5

0

Average Velocity (m/s)

0 50 100 150 200 250 300

F8_1426

Time (ms)

Figure 8. Average calculated velocity of the NaK

as a function of time during a startup 

transient. 
13

5. CONCLUSIONS

The COMSOL Multiphysics model developed in this work, while still incomplete and very 

simplified, has demonstrated the capability to qualitatively capture many of the experimental data 

trends observed in testing of an ALIP. The intricate three-phase coil configuration correctly replicates the observed axial-traveling magnetic wave and establishes a net Lorentz body force on the 

fluid, forcing NaK through the pump. Furthermore, the boundary conditions and input parameters 

can be easily varied to simulate pump operation over a range of operating conditions, permitting 

the generation of pump performance curves (efficiency as a function of flow rate). While it may not 

be desirable to generate fully nonlinear, fully time-dependent solutions of the problem, there are 

several less accurate or simplified methods with which the model can be solved that can be used to 

provide a rapid check on the solution methodology being employed. Though additional validation 

is still required, a simplified solution method and the approximate model presented in this TM may 

be very useful in developing a systematic understanding of measured ALIP performance scaling as 

a function of different physically controllable parameters.
14

APPENDIX—HIPERCO 50 B-H DATA

The nonlinear B-H curve for Hiperco 50, as provided by the manufacturer, Carpenter 

Technology Corporation, Reading, PA, is presented in figure 9.

0

0

0.5

1

1.5

2

2.5

2 4 6 8 10 12 14 16

Induction, B (T)

Magnetizing Force, H (kA/m)

F9_1426 Figure 9. Hiperco 50 B-H curve data (taken for material 

strips with a heat treatment of 871 oC (1,600 oF)). 
15

REFERENCES

1. Nainiger, J.: “Affordable Fission Surface Power System Study Final Report,” NASA Exploration 

Systems Mission Directorate Report, Glenn Research Center, Cleveland, OH, October 2007.

2. Mason, L.S.: “A Comparison of Fission Power System Options for Lunar and Mars Surface 

Applications,” NASA/TM—2006–214120, Glenn Research Center, Cleveland, OH, 21 pp., 

February 2006.

3. Mason, L.S.: “A Practical Approach to Starting Fission Surface Power Development,” NASA/

TM—2006–214366, Glenn Research Center, Cleveland, OH, 11 pp., July 2006.

4. Mason, L.S.; Poston, D.; and Qualls, L.: “System Concepts for Affordable Fission Surface 

Power,” NASA/TM—2008–215166, Glenn Research Center, Cleveland, OH, 17 pp., January 

2008.

5. Polzin, K.A.; Pearson, J.B.; Schoenfeld, M.P.; et al.: “Performance Testing of a Prototypic 

Annular Linear Induction Pump for Fission Surface Power,” NASA/TP—2010–216430, 

Marshall Space Flight Center, Huntsville, AL, 118 pp., May 2010. 

6. Polzin, K.A.; Pearson, J.B.; Webster, K.; et al.: “Testing of an Annular Linear Induction Pump 

for Fission Surface Power Technology Demonstration Unit,” NASA/TP—2013–217487, Marshall Space Flight Center, Huntsville, AL, 36 pp., August 2013.

7. Goldsteins, L.; Buligins, L.; Fautrelle, Y.; et al.: “Numerical Quasi Stationary and Transient 

Analysis of Annular Linear Electromagnetic Induction Pump,” Proceedings of the 2013 

COMSOL Conference, Rotterdam, The Netherlands, October 23–25, 2013.

8. Maidana, C.O.; Werner, J.E.; and Wachs, D.M.: “Design of an Annular Linear Induction Pump 

for Nuclear Space Applications,” Paper No. 3236, Proceedings of Nuclear and Emerging Technologies for Space 2011, Albuquerque, NM, February 7–10, 2011. 

9. Polzin, K.A.: “Liquid-Metal Pump Technologies for Nuclear Surface Power,” NASA/

TM—2007–214851, Marshall Space Flight Center, Huntsville, AL, 36 pp., March 2007.
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Multiphysics Modeling of an Annular Linear Induction Pump

With Applications to Space Nuclear Power Systems

J. Kilbane and K.A. Polzin

George C. Marshall Space Flight Center

Huntsville, AL 35812

National Aeronautics and Space Administration

Washington, DC 20546–0001

Unclassified-Unlimited

Subject Category 20

Availability: NASA STI Information Desk (757–864–9658)

Prepared by the Propulsion Systems Department, Engineering Directorate

M–1377

Technical Memorandum

NASA/TM—2014–217501

ALIP, annular linear induction pump, multiphysics modeling, space nuclear power, nonlinear modeling,

electromagnetic pump

01–03–2014

UU 28

NASA

U U U

An annular linear induction pump (ALIP) that could be used for circulating liquid-metal coolant in a fission 

surface power reactor system is modeled in the present work using the computational COMSOL Multiphysics 

package. The pump is modeled using a two-dimensional, axisymmetric geometry and solved under conditions 

similar to those used during experimental pump testing. Real, nonlinear, temperature-dependent material properties can be incorporated into the model for both the electrically-conducting working fluid in the pump (NaK-78) 

and structural components of the pump. The intricate three-phase coil configuration of the pump is implemented 

in the model to produce an axially-traveling magnetic wave that is qualitatively similar to the measured magnetic 

wave. The model qualitatively captures the expected feature of a peak in efficiency as a function of flow rate. 

STI Help Desk at email: help@sti.nasa.gov

STI Help Desk at: 757–864–9658

National Aeronautics and

Space Administration

IS20

George C. Marshall Space Flight Center

Huntsville, Alabama 35812