airfoil bearings

Air Foil Bearing

2011

Neuros Co., Ltd

2 Turbo Energy R&D Center

Air Foil Bearing

Air film is generated automatically by the hydrodynamic interaction between

viscous fluid and foil structure in a rotating sleeve.

Elasto-Hydrodynamics : Elasticity + Reynolds Eqn. for Lubrication

Running Air Film Thickness : 5 ~ 20 m

Application : Oil-Free Small & High Speed Rotor

Principle of Air Bearing Hydrodynamic Pressure Generation

U

Pressure Distribution

Velocity Distribution


Applied Configuration

Bump Type : 2 Journal Bearings + 2 Thrust Bearings

Journal Bearings : Rotor Weight + Unbalance Load + Instability Operability

Thrust Bearings : Thrust Load + Tip Clearance Control + Power Loss Performance

Journal Bearing Thrust Bearing


Principle

Elasto-Hydrodynamics

Semi-Empirical Method

Iterative Solution

Relaxation Factor

Hydrodynamics Reynolds Eqn Compressible Viscous Fluid Dynamics FDM : Nonlinear Pressure Distribution Geometry (by Elastic Deformation of Top Foil)

Elasticity Beam or Plate Theory Linear Elastic Deformation FEM Foil Deflection Force (by Pressure from Hydrodynamics) Journal Bearing Thrust Bearing


Elasticity of Foil Structure

Top foils are supported by bump springs

Top foil : Geometry for hydrodynamics

Bump foil : Considered as spring with

Foil structure is designed to be in elastic range of

material Infinite life with normal operation

Bk

Top Foil

Bk E

EI

L

Bump Foil

i+1uuiiu' u'i+1

ff

m i+1m i

i+1i

Strain,

Stress,

Limit

2 (30%)

1: Rotor Weight

Limit : Elastic Range

2 : Max. Value in Running

1 (10%)

FEM Analysis of Bump


Advantages of Air Foil Bearing

Noncontact Bearing Long Life / No. Scheduled Maintenance

Improved Performance : Low Power Loss

Low Noise and Vibration

Oil-Free Higher Reliability : Simple, No Oil Lub. System

System Weight Reduction : over 15% of Total Weight

Soft Failure : Easy to Replace

High Speed Operation : ~ 4 million DN (Others ~ 1 million DN)

Environmental Durability Low and High Temp. : Cryogenic ~ 650 C

Process Fluid Operation : Air, Neon,Helium, Xenon, Refrigerants, Liquid Oxygen, Liquid Nitrogen

More Stable Rotor Structure Larger Bearing Journal Size : D 40mm at 100,000 RPM

Increase Stiffness Property of Rotor

Bigger Critical Speed Margin


Comparison with Other Bearings

High DN Number : D (Diameter in mm) x N (RPM)

Reliable, Long Life, Simple, and Environment-friendly

Rolling Element Bearing

Small

Low Loss

High Load

Noisy

Short Life

Limited DN

Aero Engine

Small Machine

Fluid Film Bearing

Long Life

Low Vibration

Hydrodynamic

Complex

High Loss

Limited DN

Industrial Machine

Air Foil Bearing

High Speed

Simple/Oil-less

Low Loss

Low Load

Coating

Small Rotor

ACM

Small Machine


Rotordynamics using Air Foil Bearing

106

107

108

0

10000

20000

30000

40000

50000

60000

Ball Bearing

Air Foil Bearing

Ro

tati

on

al S

peed

, R

PM

Supports Stiffness, N/m

79%

7%

Operating Range

1st

2nd

3rd

Ball Bearing

Industrial Turbo Machine : Motor + Compressor + Turbine

Stable Critical Speed Design with Air Foil Bearing

Air Foil Bearing


Application of Air Foil Bearing

ACM for ECS (Cabin Pressurizing/Avionics Cooling)

Small / High Speed Rotor :


Application to Industrial Machines

Applied to Various Turbo Machines: ~ 100,000 RPM, ~ 600 C

Turbo Blowers with High Speed Motor : Advanced Application

20000 40000 60000 80000 100000 1200000

20

40

60

80

100

Potential Region

Jo

urn

al B

eari

ng

Dia

mete

r (m

m)

Rotor Speed (RPM)

Turbo Blower

Turbo Compressor

Microturbine

Cryocooler

Pathfinder

Region I

Region II

Region III

Region I : Conventional ACM, Turbo Expander Mircroturbine

Region II : Medium Turbo Compressor Microturbine

Region III : Advanced Turbo Blower


Developed Air Foil Bearings

Group 1 Group 2 Group 3 Group 4 Group 5 Group 6

Application Turbo Blower Cryocooler Micro Turbine NRL Motor Compressor for PEM FC

ACM for

Aircraft

Power 30 ~ 300 hp 38 kW 65 kW 200 kW 15kW Cooling 2kW

Motor PMSM PMSM PMSM PMSM PMSM -

RPM 17,000~60,000 100,000 61,300 70,000 96,000 60,000

Journal Dia. 40~90 mm 40 mm 50 mm 60 mm 25 mm 25 mm

Rotor Mass 3~26 kg 2.6 kg 12 kg 8.6 kg 0.9 kg 0.6 kg

DN 3.6 million 4 million 3 million 4.2 million 2.4 million 1.5 million

Temp. ~ 200 C ~ 200 C ~ 600C ~ 200 C ~ 200 C ~ 200 C

Fluid Air, Gas Air, Gas Air Air Air Air


Features

Motor : 50 ~ 300 HP

PD : 0.3 ~ 1.0 kgf/cm2

TD : 58 ~ 106 C

High Efficient Compressor

High Speed Motor/Inverter

Air Foil Bearing

Cooled by Itself

Sewage Treatment

Pneumatic Conveying

Air Supply for

Chemical Process

Ventilation

Cooler

Application 1


Application 1


Application 2

PMSM for Neon Compressor

38 kW at 100,000 RPM

Gas Foil Bearing


Application 3

Cogeneration System using a Microturbine : 65 kW

Life : 30,000 hrs (Time Between Overhauls)

Noise : 65dB @10m


Application 3

Vibration Free Rotor System

Oil Free System Air Foil Bearing

Flexible Coupling Design

Critical Speeds

1st 2nd 3rd 4th 5th

Analysis 11,760 12,150 15,160 19,387 140,260

Experiment 10,300 10,650 14,970 17,970

(RPM)

Flexible Coupling Mircroturbine Rotor Assembly


Application 4

Micro Air Compressor for PEM Fuel Cell

15 kW @ 96,000 RPM

Operating temperature : -20C to 50C


Application 5

ACM for Aircraft POD

Cooling Capacity 2 kW

40,000 ~ 60,000 rpm


Air Foil Bearing Test Rig 1

Journal Bearing Test Thrust Bearing Test

Air Turbine Driven : ~ 30,000 RPM

Loading by Pneumatic Device : ~ 80 kgf

Journal & Thrust Bearing Test



Motor Driven : ~ 120,000 RPM


Journal & Thrust Bearing Test

Journal Bearing Test Thrust Bearing Test



Motor Driven : ~ 42,000 RPM


High Temperature Environment : ~ 600 C

High Temp. Test



On/Off Test for Endurance of Coating : 20,000 Cycles

Rotor Mass : 2.6 kg

Motor Driven

Automation Using LabView

On/Off Test


Endurance Test Results

Vibration (Shaft Disp.)

Journal Bearing Surface Shaft Surface

RPM Profile



Rotor-Bearing Simulator : Air-lubricated, Rotor Mass 13.2 kg

75kW Motor(PMSM) with Inverter : Accurate Speed Control

Axial Loading Mechanism : Pressurizing on Rotating Disk

Power Loss Evaluation by Temperature & Cooling Flow Rate

Max. 30,000 RPM and 100 kgf

Air Foil Thrust Bearings

Cooling Air In

Pressurizing Chamber

Cooling Air Out

High Speed Motor

Air Foil Journal BearingsLabyrinth Seal

LM

Guide

Pressurinzing Air In

Load Cell

Rotor-Bearing Simulator



Rotor-Bearing Simulator : Air-lubricated, Rotor Mass 26 kg

223kW Motor(PMSM) with Inverter

Axial Loading Mechanism

Max. 25,000 RPM and 100 kgf

Rotor-Bearing Simulator


Lift Off Speed of Journal Bearing

Rotor Mass : 14.7 kg

Lift Off Speed : 2,000 RPM


Endurance at Field Operation

50hp Turbo Blower : Steel Company

Field Operation : 20,000 On/Off

Cycles


Endurance Test of FC Compressor

20hp Compressor for PEM FC

1,000,000 On/Off Cycles


Blower : Low Pressure Compressor

Pressure Ratio : 1.3 ~ 2.0

Type

Positive Displacement Blower : Roots

Turbo Blower : Gear Box Type / High Speed Motor

Efficiency, Maintenance, Noise : Roots Type Turbo Type

Application

Air Supply : Waste Water Treatment, Power Plant Desulfurization

Raw Power Transportation : Cement Industry, Petrochemical Industry

Ventilation / Cooling / Vacuum

Roots Blower Turbo Blower


Applications of Blower

3 ~ 10 m

Air

Blower

Waste Water Treatment

Aerobic microorganisms dissolve contaminants by blowing air into sewage


Turbo Blower Gear Driven Turbo Blower

Low Speed AC Motor

Coupling + Gear Box + Compressor

Fluid Film Bearing

Large & Complex

Oil System & Cooling System

Periodical Maintenance (G/B, Coupling,Bearing)

High Speed Turbo Blower

High Speed Motor

Single Rotor : Compressor + Motor

Air Foil Bearing

Small & Simple

Oil Free System

Maintenance Free


Dr. Dellacorte(NASA) visit (2007.9 / 2010.9)

airfoil bearings

Documents

hydrodynamics bump foil

foil elasticity beam

high speed operation

air film thickness

high speed simpleoil

industrial turbo machine

hydrodynamics journal

bearings high dn number