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Type of Seals
• - Annular plane seal- Grooved seal- Labyrinth seal- (Hole pattern )Damper seal- Honeycomb seal- Brush seal- Foil seal
• - Cloth seal
• - Abradable seal
Gas Turbine Seal Locations
Advanced seals locations on a Frame 7EA gas turbine Ref.) J. of Turbomachinery, Vol. 124, 2002 pp. 293
Seal Characteristics Evaluated by Design Tools Duringthe Design Process
BrushSeal
Labyrinth Seal
Floating Ring Seal
Honeycomb Seal
FoilSeal
GroovedSeal
Hybrid
Non-
Contact
Seal
Type of Seals
스팀 터빈에서의 손실율
(GE Power Generation 1996)
Labyrinth seal-패킹 링의 구조 및 원리
가변간극 패킹 링의 원리 및 효과
작동원리
개선효과(Heat Rate Improvement for VCPP in 500MW unit)
기존 패킹 링과의 비교
일반 패킹
가변간극 패킹
Labyrinth seal 의 해석
1-Control Volume Model
Governing Equations
연속방정식:
원주방향운동량 방정식:
가변 간극 실 실험장치
• Rotor의 Modal Analysis
– ARMD에 의한 해석 결과
1st mode: 182.7 Hz
2nd mode: 295.0 Hz
3rd mode: 2287 Hz
– 실험적 Modal Test 결과
1st mode: 184 Hz
Bearing Stiffness: 3.0 X 10^8 N/m
가변 간극 실 실험
시스템의 작동조건입력을 위한 설정 창
실과 각 cavity의 치수 설정
통합 해석 코드 개발
가변간극 실험 및 해석
• 가변간극 실의 작동조건 해석
• 사용된 설계변수Li = 15.4mm, Lo = 6.6mm, w = 22mm,
Po = 0.1MPa, r = 113mm
Pi = 0.109MPa (1.09 bar)
누설량 실험 및 해석
• Δp 값에 따른 누설량 해석 결과와 비교
• 해석결과– 해석결과 또한 Δp가
증가할수록 누설량이 증가하며, 실험과해석과의 오차는6.77%~ -6.47%로서유체가 공기라는 점을 감안하면 실제와해석결과가 잘 맞는것을 볼 수 있다.
Flow factor 의 비교
<Del p값에 따른 Flow factor>
0 100 200 300 400 500 600 7000
3
6
9
12
15
18
21
24
27
Flow
fact
or, (
kg*K
^1/2
)/(M
Pa*
m*s
)
Pressure drop across seal, kPa
동특성 실험 및 해석
Structure Hydrodynamic
of SealRotor
Housing
• 이론적 배경– 마그네틱 베어링 시스템을 스프링과 댐
퍼로 모델링 할 수 있다.
– 초기에는 작동유체가 없는 정적인 상태에서 Hij를 구해 test rig의 계수를 구하고 다시 작동유체의 유입상태에서 측정하여 실의 동적효과가 포함된 계수를구한 후에 두 조건으로부터 얻은 각 계수들의 산술적 연산을 하면 실의 효과에만 의한 동역학적 계수를 얻을 수 있다.
동특성 실험 및 해석
To Improve Stability for Steam Turbine, gas Turbine, Compressor;
- Tooth-on stator labyrinth seal을smooth rotor/Honeycomb Stator Seal로 대
체;
- To Improve Leakage Performance
- Numerical analysis for Turbulent liquid, gas seals
- Honeycomb Core와 Support Back Steel 사이에 Brazing Filler Metal(BFM)을 두고Brazing.
- 가스터빈엔진용 BFM은 비결정질의 Ni 기지합금으로 1,000℃이상의 온도에서 용융.
Honeycomb Seal
가스 터빈 Brush Seals
< Brush Seal Clearance 20% of Typical Labyrinth Seal or Lower>
Typical brush seal designs for a) steam turbineb) gas turbine applications
(a) Typical steam turbine brush seal packing ring assembly.(b) 7EA gas turbine HPP brush seal after 22,000 h ofoperation.
Ref.) J. of Turbomachinery, Vol. 124, 2002
Typical performance benefits for brush seals
Turbine Class and Location Efficiency Benefit
Utility Steam Tubines (HP Section)
End Packings (multiple locations) 0.1-0.2% unit heat rate
Interstage Packing (multi stages) 0.5-1.2% HP section efficiency; 0.1-0.2% unit heat rate
Industrial Steam Turbines
End Packings (multiple locations) 0.4-0.8% efficiency
Intestage Packing (multi stages) 0.2-0.4% efficiency
Ref.) J. of Turbomachinery, Vol. 124, 2002
Leakage performance for Brush seal vs. Labyrinth seal
Leakage characteristics of a typical seal under sealinterference and clearance conditions .y scale shows the ratio of Brush seal leakage at a specified condition seal line-to-line leakage.
Ref.) J. of Turbomachinery, Vol. 124, 2002 pp. 293
From top left corner, clockwise. 1) Brush seal clearance due to wear versus labyrinth seal clearance due to rub, 2) brush seal flow versus labyrinth seal flow, 3) additional kW-h saving of the brush seal in the sealing system, 4) brush seal performance degradation over 3 yr .as new seal provided additional 1.1 percent MW, after 3 yr provided 0.7 percent MW, seal returned to the machine after engine overhaul for additional 3 yr service the seal during overhaul.
7EA machine HPP brush seal field dataduring 22,000 h of operation:
Ref.) J. of Turbomachinery, Vol. 124, 2002 pp. 293
1) Transient Capability/Stable Brush Seals;- From current seal to 3-5 times dynamically more aggressive engine seals.
2) High Surface Speed;From 120 m/s of AE seal to 244 m/s of GT seals, now moving to 500 m/s.
3) High Pressure Loading;- From 0.69 MPa two stage seals to 2.76 MPa single design, now moving to higher pressure drop multi-stage seal design.
4) High Swirl Flow Field;- Swirl ratios of current applications are 0.3 now moving to 0.6-1.2 region.
5) Air Temperature;From 370 oC to 650-1000 oC temperature
6) Seal Life and Durability;- GT fleet leader w/40000 field hrs w/minimum degradation.- ST fleet leader 40000 field hrs w/minimum degradation.
7) Rotor Surface;- Ceramic coated AE rotors to uncoated GT and ST application.- Interrupted surface at bucket tip seals
Brush Seal Technology Status/MilestonesRef.) J. of Turbomachinery, Vol. 124, 2002
Stiffness&Damping Mechanism
At high speed when the air film becomes stiff, foil structure provides more damping than gas film. Therefore, dynamic characteristics of foil Seals and bearings depend on foil structure.
Hydrodynamic
Air Film
Journal
Compliant Foil structure
Bearing SleeveAir Bump Foil Air Bump Foil Seal/BearingSeal/Bearing
bump foil
top foil
housing
Journal
Air Foil Seal/BearingAir Foil Seal/Bearing
Ref.) MiTi Co.
Bearing/Seal
Concept
Theory Verification
Testing
Hydrodynamic Performance
Materials
Bearing/SealImperfections
Acceptance
Testing in
Advanced
Application
Reliability
Life
Economy
Application Testing in Dynamic Simulator
Dynamic Response
Mechanical Compliance
Design Envelope
ThermalDeformation
Rotor Misalignment
Vibration Specifications
Input:Seal GeometryLubricant Charac.SpeedTemperaturePressureLoad
Output:Film ThicknessPower LossStiffnessDampingOnset of Instability
Bearing/SealAnalysis
Seal and Bearing Research in KIST Seal and Bearing Research in KIST -- Development Flowchart Development Flowchart
Friction and Wear Data Summary (KIST)
Friction and Wear Data Summary (NASA)
Friction Coefficient of CORONA 100 Coating Material (KIST)
고온 공기 포일 베어링 테스트 시험기 (1000℃)
Coating Process of CORONA 102 Coating Material (KIST)
“CORONA” (KIST) vs. PS304 (NASA) for Seals and Bearings(Patent pending in USA, EU)
Floating Ring SealFloating Ring Seal Critical Technology- Fluid dynamics of pump & turbine elements- High precision manufacturing- Rotordynamics
* cryogenic bearing* high performance sealing unit* rotordynamic stability
Turbine2BoosterInducer(LO ) Impeller(LO2)
SeparateImpeller
InducerImpeller(LCH4)
1 25 6 3 87 4Oxygen pump section Fuel pump section
FloatingFloating
ringring
Clamping nutClamping nut
Support ringSupport ring
Inducer (LO 2)
Floating Ring Seal for Liquid Rocket
Characteristic of floating Ring Seal- Floating ring seal has analytically dynamic
characteristics ; such as excellent stiffness, damping at high operating speed. Stability is higher than the other seal- labyrinth, damper, plain seal.
