research community’s perspective to streamline engine
TRANSCRIPT
Dr Yi-Guang Li PhD, MSc, BSc, ASME Fellow
Reader in Gas Turbine Technology
School of Aerospace, Transport and Manufacturing, Cranfield University, UK
24th ISABE Conference
Short Course
RAeS-IMechE Seminar on MRO Crisis:
Challenges and Opportunities
(26th November 2019)
Research Community’s Perspective to Streamline Engine Maintenance
Gas Turbine Engine Degradation
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Courtesy of Rolls-Royce
Pro
bab
ility
of
Failu
re
Time to Failure Average Time to Failure
Life given to Users
Unfavourable operating
environment
Favourable operating
environment
• Fouling
• Corrosion
• Erosion
• FOD
• Tip clearance damage
• etc.
Maintenance Strategies
Corrective Maintenance (Run to failure)
Preventive Maintenance (Time-Scheduled)
Predictive Maintenance (Condition-Based)
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Condition monitoring is the supporting technology
Integrated Condition Monitoring Systems
Integrated Condition Monitoring
system
Oil analysis and
debris monitoring Vibration
Monitoring
HPT Temperature
entry spread
Gas Path
Monitoring
Limited
Transient
Monitoring
Visual
Inspection
Life
Consumption
Monitoring
Degradation & Failure Prediction
Exhaust
Temperature
monitoring
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Digital Twins for Operation and
Maintenance
Digital twins – computerized companion of physical asset that can
be used for various purposes (Wikipedia):
- Performance modelling
- Condition monitoring
- Remote operation & control
- Condition based maintenance
Courtesy of Rolls-Royce
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Performance Adaptation
(towards digital twins)
Pe
rfo
rma
nce
Real
Simulated
Ambient and Operating Conditions
Pe
rfo
rma
nce
Real
Ambient and Operating Conditions
Simulated
Design-Point (DP) adaptation
Off-Design (OD) adaptation
Li Y.G., Pilidis P. and Newby M., “An Adaptation Approach for Gas Turbine Design-Point Performance Simulation”, ASME Journal of Engineering for Gas Turbine and Power,
Vol. 128, pp.789-795, October 2006.
Li, Y.G., Abdul Ghafir M.F., Wang L., Singh R., Huang K., Feng X. and Zhang W., “Improved Multiple Point Non-Linear Genetic Algorithm Based Performance Adaptation
Using Least Square Method”, ASME Journal of Engineering for Gas Turbines and Power, Vol. 134, pp.031701, March 2012. 6
Performance Adaptation
(towards digital twins)
Design Point (DP) Adaptation Off-design (OD) Adaptation
Errors before OD adaptation
Errors after OD adaptation
Test Data
Errors at DP after DP adaptation
Application of Performance Adaptation to GE LM2500+ Engine in Manx Utilities,
Isle of Man, UK
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Engine Health Monitoring
- Gas Path Diagnostics & Prognostics
To detect and/or forecast engine gas path component degradation
or faults using gas path measurements
Li Y.G. and Singh R., “An Advanced Gas Turbine Gas Path Diagnostic System - PYTHIA”, ISABE-2005-1284, the Seventeenth International
Symposium on Airbreathing Engines (17th ISABE), Munich, Germany, September 2005.
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Gas Path Analysis (GPA) Artificial Neural Networks Genetic Algorithms Expert Systems Data driven …………………..
Engine Health Monitoring
- Gas Path Diagnostics & Prognostics
Engine Model
Data Acquisition & Correction
Measurement Selection
Sensor Fault Diagnostics
Component Diagnostics
Model Performance Adaptation
Results
Courtesy of Rolls-Royce
Measurement data
Measurement data
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Engine Prognostics
Engine Health Monitoring
- Gas Path Diagnostics
Pythia Software Application:
CCGT power plant using two GE
LM2500+ engines at Manx Utilities in
the UK
Pythia performance and diagnostic
system/software for condition
monitoring of gas turbine engines
Blinstrub J., Li Y.G., Newby M., Zhou Q., Stigant G., Pilidis, P. and Honen H., “Application of Gas Path Analysis to Compressor Diagnosis
of an Industrial Gas Turbine Using Field Data”, GT2014-25330, ASME TURBO EXPO 2014, Dusseldorf, Germany, June 2014.
Courtesy of Manx Utilities, Isle of Man, UK
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Performance Status Monitoring
xhz
Turbine Entry Temperature
Engine mass flow rate
Compressor PR, Eff.
Bypass ratio
Turbine Eff.
Cooling flows
Fuel flow rate
Thrust / Power
Pressures
Temperatures
Shaft speeds
Courtesy of Rolls-Royce
Performance parameters: Gas path measurements
Li, Yi-Guang, “Aero Gas Turbine Flight Performance Estimation Using Engine Gas Path Measurements”, AIAA Journal of
Propulsion and Power, Vol. 31, No. 3, May-June 2015. 11
Performance Status Monitoring
Model aero gas turbine similar to EJ200 turbofan
Performance specification comes from open literature
Cranfield Pythia software is used to build up the performance model
Performance estimation method is implemented into Pythia
Performance Estimation for Engine at Flight (H = 8km) - Degraded performance
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Creep Life Consumption Monitoring
Condition parameters
Life Estimation model
Stress model
Thermal model
Creep model
Reference operating condition
Creep Factor
RefLc
LcCF
Creep Factor
𝐿𝑐 - Creep life
1FCPresent condition creep life is equivalent to the life at ref. condition
1FCEngine is operated at a better condition thus increasing the creep life
1FC Engine is operated at a much worse condition thus reducing the creep life
Abdul Ghafir M.F., Li Y.G., Wang L. and Zhang W., “Impact Analysis on Aero-Engine Performance Parameter Variation on Hot Section’s
Creep Life Using Creep Factor Approach”, ISABE-2011-1609, 20th ISABE Conference, Gothenburg, Sweden, 12-16 September 2011. 13
Equivalent Operating Time (EOT) and
Remaining Useful Life (RUL)
Degradation Equivalent Operating Time (EOT)
𝐸𝑂𝑇 = 𝐷
𝐷 𝑟𝑒𝑓× 𝑡
• Degradation EOT is a converted operating time for an engine or its components.
• It expresses engine component performance degradation relative to a reference operating condition.
𝐸𝑂𝑇 = 𝐸𝑂𝑇 𝑓𝑎𝑐𝑡𝑜𝑟 × 𝑡
𝐷 = Component health degradation 𝐷 = Degradation rate at current operating condition
𝐷 𝑟𝑒𝑓 = Degradation rate at reference condition
𝑡 = Actual operating time spent at this condition.
𝐸𝑂𝑇 𝑓𝑎𝑐𝑡𝑜𝑟 = 1 +𝐷 𝑓 + 𝐷 𝑒 + 𝐷 𝑥
𝐷 𝑟𝑒𝑓+ 𝛼 ∙
𝐷 𝐶
𝐷 𝐶.𝑟𝑒𝑓
𝑓 = Fouling 𝑒 = Erosion 𝑥 = Additional degradation mechanism 𝑐 = Creep strain. 𝛼 = Contribution of blade creep strain to tip wear and performance loss
where:
Alozie O, Li Y.G., Diakostefanis M., Wu X., Shong X. and Ren W., “Assessment of Degradation Equivalent Operating Time for Aircraft Gas Turbine
Engines”, ISABE-2009-24419, the Twenty-Fourth International Symposium on Airbreathing Engines (24th ISABE), Canberra, Australia, September 2019. 15
Equivalent Operating Time (EOT)
and Remaining Useful Life (RUL)
Flight Mission: Altitude, Mach number and Fan Speed vs. Flight Time
Tip rub starts
Tip rub stops
RUL Prediction
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How Can Condition Monitoring Benefit us?
Investment
Cost Saving
Net Saving (ROI)
Loss
Loss
Condition Monitoring System Complexity
Mo
ney
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Summary
New technologies offer potentials to streamline engine operation and maintenance and meet MRO challenges:
- Moving from preventive (scheduled) maintenance to predictive (condition-based) maintenance
- Condition monitoring & Digitalization (digital twins) are two of the key technologies
Optimal use of the technologies to get maximum return of investment
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