ACKNOWLEDGEMENTS

We take this opportunity to express our deep sense of gratitude and sincere thanks to

our guide Dr. SOUMENDU JANA, Scientist, Propulsion Division, CSIR National

Aerospace Laboratories, NWTC Belur, Bangalore, for his meticulous guidance, words of

advice, continuous support throughout the investigation.

We shall remain ever grateful to Shri. SHYAM CHETTY, Director and

Sri. M.JAYARAMAN, Head of the Department, Propulsion Division, CSIR National

Aerospace Laboratories, NWTC Belur, Bangalore, who suggested this topic, gave valuable

advice.

We express our gratitude to Dr. RAMACHANDRAN, beloved principal Vemana

Institute of technology, Bangalore for his continuous support and encouragement during the

completion of our course.

We are greatly indebted to Mr. VIJAYSIMHA REDDY B.G. Head of the

Department Mechanical Engineering, Vemana Institute of technology, for his words of

advice and encouragement during the investigation.

We are thankful to our internal guide Mr. N. Raghavendra, Asst. Professor,

Department of Mechanical Engineering, Vemana Institute of technology, Bangalore for his

valuable instructions and assistance to carry out our project work.

We extend our thanks to Dr. S. Sridhara Murthy, Head, Knowledge and

Technology Management Division, CSIR National Aerospace Laboratories.

We also extend our thanks to Machine Tool Reconditioners, Karnataka

Engineering Services, CSMST workshop, NTAF and Propulsion workshop for their

contribution towards the successful fabrication of our setup.

We express our profound thanks to all our respected and beloved scientists and

employees of National Aerospace Laboratories, NWTC Belur and Engineering services

Kodihalli, Bangalore for their constant support and guidance.

We are grateful to our parents for their moral support and encouragement throughout.

Finally we gratefully acknowledge all our friends and well wishers whose contributions have

been invaluable to complete this work successfully.

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ABSTRACT

The ever increasing demand for machineries and space applications in developing

countries motivates the search for harmless working conditions and mitigate many of the

concerns and limitations encouraged in conventional axial bearings such as wear, leaks, seals

and friction loss.

The Radial Halbach Magnetic Bearing is inherently stable and requires no active

feedback control system or superconductivity as required in many magnetic bearing designs.

The Radial Halbach Magnetic Bearing is useful for very high speed applications where

conventional bearings cannot be used including turbines, instrumentation, and medical

applications. In addition, this technology has potential application in ultra-efficient motors,

computer memory systems, manufacturing equipment and space power systems such as

flywheels.

The Radial Halbach Magnetic Bearing employs many advanced technologies. The

innovative physical layout consists of a rotor and a stator. The rotor is contained within a

static shell assembly or stator. Magnetic fields suspend and support the rotor assembly

within the stator. Advanced technologies developed for particle accelerators, and currently

under development for maglev trains and rocket launchers, served as the basis for this

application.

A small scale experimental hardware system was successfully designed and

developed to validate the basic principles described, and the theoretical work that was

performed. The report concludes that the implementation of Radial Halbach Magnetic

Bearings can provide significant improvements in rotational system performance and

reliability.

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NOMENCLATURE

q : Electric Charge

v : Velocity in m/s

E : Electric Field V m-1

B : Magnetic Field in Tesla

k : Stiffness in N/m

F : Force in N

δ : Displacement/ deflection in m

µ :   Permeability in N.A−2

µ0 : Absolute permeability = 4π*10-7 N.A−2

µr : Relative permeability = µ/ µ0

V : Volume in m3

W : Weight in N

L : Length in m

Do : Outer diameter in m

Di : Inner diameter in m

E : Young’s Modulus in N/m2

I : Moment of inertia in m4

fn : Natural frequency in Hz

Nc : Critical speed in rpm

g : Acceleration due to gravity = 9.81 m/s2

ρ : Density in Kg/m3

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LIST OF FIGURES

Fig. No. Title Page no.

1.1 Simple Magnetic Bearing 2

1.2 Charge Distribution 5

1.3 Application of Magnetic Bearing 6

2.1 Radial Halbach Magnetic Bearing Test Model Components 8

2.2 Categories of Magnetic Bearing 9

2.3 Structural Forms of Passive Magnetic Bearing 14

2.4 Radial Passive Magnetic Bearing 15

2.5 Description of Force as Function of Displacement 15

2.6 Active Magnetic Bearing 18

2.7 Halbach Array 20

2.8 Magnetization in Halbach Array 21

2.9 Halbach Orientation 22

2.10 Halbach Model 22

3.1 Halbach Array for Design 24

3.2 Test Rig 25

3.3 Hub 26

3.4 Stator 28

3.5 Shaft 29

3.6 Shaft under Load 30

3.7 Base Plate 33

4.1 Shaft Tight-Fitted To Rotor 34

4.2 Stator with Copper Coils 35

4.3 Base Plate with Grooves for Assembly 36

5.1 Magnetic Bearing – Front view 39

5.2 Magnetic Bearing under Test 40

iv