magnetic bearings for smart aero-engines magflymagfly · the prognosis is that future aero-engines...

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MagneticMagnetic Bearings for Smart AeroBearings for Smart Aero--EnginesEngines

K.-H. Becker MTU Aero Engines

MagneticMagnetic BearingsBearings

forfor SmartSmart AeroAero--EnginesEngines

MAGFLYMAGFLY

K.-H. Becker

MTU Aero Engines

FifthFifth AeronauticsAeronautics Days 2006Days 2006

1919thth –– 2121stst JuneJune 20062006

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TechnionTechnionTRDFTRDF

TheThe ConsortiumConsortium::

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Today's aeroToday's aero--engines are designed withengines are designed withmechanical bearing systems, whichmechanical bearing systems, whichconsist of ball or roller bearings, oftenconsist of ball or roller bearings, oftensupported by squeeze film dampers.supported by squeeze film dampers.

ballball oror thrustthrust bearingbearing

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combustioncombustionchamberchamber

Low Pressure CompressorLow Pressure Compressor

High Pressure CompressorHigh Pressure Compressor

Low Pressure TurbineLow Pressure Turbine

bearing locations (roller and ball)bearing locations (roller and ball)

FanFan casingcasing

High Pressure TurbineHigh Pressure Turbine

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bearingbearingcagecage

brgbrg outer raceouter race

rollerroller

squeeze filmsqueeze film

oil feedoil feed

brgbrg inner raceinner race

to bearingto bearinglubricationlubrication

sealingsealing

roller bearing withroller bearing with squeeze film dampersqueeze film damperboth cooled and lubricated with oilboth cooled and lubricated with oil

oil inoil in

oil jetoil jet

bearingbearing lubricationlubrication throughthroughcentercenter ofof thethe inner ringinner ring

outer raceouter race

innerinnerracerace

ballball

rotating partsrotating parts

cagecage

oil streamoil stream

oiloiloutletoutlet

oiloil inin

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All over the world, but particularly in the United States and in Europe, there is a drive towardsgreater efficiency with the 'More Electric Aircraft''More Electric Aircraft' and 'More Electric Engines''More Electric Engines' programmes andthe prognosis is that future aero-engines will increasingly incorporate mechatronicmechatronic systemssystems.

Radial Bearing Statorrotorlaminationstack

statorlaminationstack& coil holders

magneticmagnetic bearingbearing

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Bearing Stiffness

Ro

tor

Cri

tica

lSp

eed

Adjustable MagneticAdjustable MagneticBearing StiffnessBearing Stiffness

Mode ShapesMode Shapes

11stst criticalcriticalbending modebending mode

22ndnd criticalcriticalbending modebending mode

33rdrd criticalcriticalbending modebending mode

Magnetic bearingscontrol stiffnessand damping tominimizetransmission ofunbalance forcesto casings andmountings

rigidrigid bodybodymodesmodes

mixedmixedmodemode

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more compact and efficient engine designmore compact and efficient engine design

lower friction losses, and hence increasedlower friction losses, and hence increasedefficiencyefficiency

ultraultra--low wear in the bearingslow wear in the bearings

reduced emissionsreduced emissions

reduced fire hazard (no oil in the engine)reduced fire hazard (no oil in the engine)

longer maintenance intervalslonger maintenance intervals

lower direct operating and lifetime costslower direct operating and lifetime costs

higher speeds and performancehigher speeds and performance

control and reduction of vibrations, noisecontrol and reduction of vibrations, noiseand stressesand stresses

One of the ideas in this direction is to substitute the current mechanical bearingsystem by Active Magnetic Bearings (AMBsAMBs). This substitution offers the prospect ofseveral advantages, specifically:

Nominal diameter: 110 mm

Radial: Max. force: 2400 N

Thrust: Max. force: 5000 N

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Magnetic Bearing LimitationsMagnetic Bearing Limitations

Larger BearingsLarger Bearingsspecific load capacity (maximum load per unit of areaof application) lower than most other bearings systems.

Higher ComplexityHigher Complexity (control)(control)Control system and interface

Requires Electrical PowerRequires Electrical PowerMagnetic bearing require power to drive theelectromagnets, control systems and sensors.

TodayToday:

power unit is still heavy for aeroplanes but removing oilsystem and its auxiliaries eliminates nearly this effect

applicable for non flying engines

but progress in superconduction and improvement ofweight to power ratio will reduce weight and size

ExampleExample: AMB: AMB controlcontrol unitunit10 channel AMB control unitMax. Output Power: 2400 VA or4800 VA per channel

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Schematic overviewSchematic overviewof MAGFLYof MAGFLYWorkpackagesWorkpackagesandandInteractionsInteractions

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LoadshareLoadshare Bearing forBearing forHeavy Rotating Machinery (rig 2)Heavy Rotating Machinery (rig 2)

Rotors up to 150kg

Two pairs of bearings:

one set with axial play

one set with zero preload

Elastic damper mounting

Grease or dry lubrication

WP 1:WP 1: ActiveActive MagneticMagnetic Bearing DesignBearing Design

LoadLoad--sharing bearingssharing bearingsdesigns and design rules for loaddesigns and design rules for loadsharing bearingssharing bearingsalternative designs to provide loadalternative designs to provide load--sharing and emergency bearingssharing and emergency bearings

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51.551.5mmmm

Characteristics:

Very good linearity

High sensitivity

Working from room temperature up to 600°C

High cost efficiency

Temperature compensated

High Temperature bearingsHigh Temperature bearingsdesign AMBs using highdesign AMBs using hightemperature resistant materialstemperature resistant materialslong term performance andlong term performance andcontrollabilitycontrollability


Principle:Eddy current position sensorsprinted on ceramic substrate

DevelopmentDevelopment ofof newnew sensorssensorsforfor thethe highhigh temperaturetemperature rigrig

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Overall AMB designOverall AMB designrequirements for AMBs in aerorequirements for AMBs in aero--engines are very specific,engines are very specific,to create a optimum AMB designto create a optimum AMB design

toto adoptadopt thethe magnaticmagnatic bearingsbearings toto thethe specificspecificrequirementsrequirements

at normalat normal temperaturetemperature operationoperation

at highat high temperaturetemperature operationoperation

rotorrotor

statorstator

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WP 2:WP 2: WholeWhole SystemSystem ModellingModelling

Develop Models of :• casing, bearing supports, shaft and rotor;• AMBs;• load-sharing bearings;

Integration of the component models into an overall representative modelof the complete system.

Incorporation of the modelling methods into a user-friendly, fast andreliable modelling tool for commercial application.

It is aimed to develop a set of validated dynamic analysis modelling tools for themajor components of a rotor system supported in AMBs, and an overall modelfor the SMART aero-engine:

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Develop Validated AMB ModelDevelop Validated AMB Model

StructuralStructural Model ofModel of MagneticMagnetic bearingbearing ElectromagneticElectromagnetic fluxfluxdistributiondistribution ModelModel

• Validating Model of Electromagnetic Forces

(i) Verify the design of the electromagnetic system making surethat no magnetic saturation takes place;

(ii) Provide an understanding of the nonlinear behaviour of thecoupled electromagnetic and structural fields;

(iii) Provide accurate estimation for the parameters from which asimplified model is made.

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WP 3:WP 3: WholeWhole EngineEngine DesignDesign

Main Objective: Verification of component and system models of thecomplete system including controllerIntegrated model used for several design analyses to assess overallperformance under different operating conditionsFocal task, needs and combines input from all other work packages

Simulate the whole system to evaluate dynamic performance

Develop robust sensitivity and optimisation procedures.

Sensor design and location

Damage Sensitivity

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whole system simulation and possible sensor locations

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whole system simulation and possible sensor locations

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Develop robust sensitivity and optimisationDevelop robust sensitivity and optimisationproceduresprocedures

- Initial design unlikely to be optimum- Full model enables parameter variation and

investigation of parameters’ interaction- Influence of AMB’s bearing stiffness

to rotor dynamic behaviour

rear bearing

0

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0

3 5 0

4 0 0

bearing stifness [N/mm]

freq

uen

cy[H

z]

Adaptation of optimisation tool Boss-Quadro tomodified SAMCEF rotor dynamic solutions allowsoptimisation of multiple analyses

Monte CarloMonte Carlo MethodMethod

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parallel / serial link or modem

sensorsensor signalsignal

++

––

powerpoweramplifiersamplifiers

rotorrotor

DSPDSPAAAA

DDDD

Fast digitalFast digitalcontrollercontroller

magnetmagnet

sensorsensor

++

--

ControlControl System and InterfaceSystem and Interface forfor SMARTSMART

improved monitoring, diagnosis, prognosis and correction capabilities in the sense of SMARTMachine Technology. SMART is used here in its original context of:

Self-Monitoring, Analysis and Reporting Technology

WP 4: SmartWP 4: Smart EnginesEngines

SMARTSMART

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Active diagnostics of rotating partsActive diagnostics of rotating parts in Aeroin Aero--EnginesEngines

• Motivation• Rotating parts are not accessible during normal operation

• Must service periodically time consuming costly• Computer controlled Active Magnetic Bearings enable in-situ inspection

• Method• Apply extremely small probing forces (no effect of magnetic levitation)• Probing forces are tuned in real-time according to a calibrated model and

instantaneous speed of rotation• Special signal processing extracts the information about any deviation from

perfect condition in rotating parts (shaft, blades)

• Advantages• Use of existing Magnetic bearings, non-contacting forces• Separate faults in rotating part from casing and non-rotating elements• Detect extremely small faults (e.g. 0.1% deviation in asymmetry)


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Activemagneticbearings

diagnosticsdisplay&probingexcitation

shaft

Disc withdefect

TechnionTechnionTRDFTRDF

Active diagnostics of rotating partsActive diagnostics of rotating parts in Aeroin Aero--EnginesEngines


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Small-defect

Asymmetric

No-defectsymmetric

Vib

ratio

nle

vel (

log )

Vib

ratio

nle

vel (

log]

Test during runup

Speed: 0 2250 RPM

Probing ω= 101.5Hz

1% fault

probing

1% defect in rotating part

Probing force by magnetic bearings

detection of fault in rotating part


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AMB AAMB A

AMB BAMB B

RingbalancerRingbalancerAA BB

MotorMotor turbineturbinedisksdisks

WP 5:WP 5: DemonstrationsDemonstrations Rig 1 (MTU) running at TU Darmstadt

0 200 400 600 800 1000

Mode Shapes (calculated, freeMode Shapes (calculated, free--free)free)

0 rpm | 51 Hz 0 rpm | 140 Hz 0 rpm | 439 Hz

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WP 5:WP 5: DemonstrationsDemonstrations Rig 2 (Turbomeca) running at ICL

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WP 5:WP 5: DemonstrationsDemonstrations High-temperature rig running EPFL

50 mm50 mm highhigh temperaturetemperature rigrig

the walls of the furnace are dismounted

highhigh temperaturetemperaturemagneticmagnetic bearingbearing

rotorrotor

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WP 5:WP 5: DemonstrationsDemonstrations Task 5.4 HighTask 5.4 High--temperature rigtemperature rig

Life span tests athigh temperature:

Magnetic andmechanical properties

magnetic bearings for smart aero-engines magflymagfly · the prognosis is that future aero-engines...

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