Assessment of degradation equivalent operating time for aircraft gas turbine engines

Alozie, Ogechukwu; Li, Yi-Guang; Diakostefanis, Michail; Wu, Xin; Shong, Xingchao; Ren, Wencheng

doi:10.1017/aer.2019.153

Cited by 13 publications

(4 citation statements)

References 32 publications

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“…The details of the simulation methods can be found in [13]. Cranfield software Pythia [14][15] on gas turbine performance, gas path diagnostics and life consumption analysis is used for this research.…”

Section: Gas Turbine Performance Modelmentioning

confidence: 99%

Thrust Rebalance to Extend Engine Time On-Wing With Consideration of Engine Degradation and Creep Life Consumption

Chiavegatto,

2024

Journal of Engineering for Gas Turbines and Power

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Airlines have consistently attempted to lower their operational costs and improve aircraft availability by applying various technologies. Engine maintenance expenses are one of the most substantial costs for aircraft operations, accounting for around 30% of overall aircraft operational costs. So, maximizing aircraft TBO is crucial to lowering the costs. This paper presents a novel method of rebalancing the thrust of engines of an aircraft to maximize the time between overhaul of the aircraft considering the performance degradation and creep life consumption of the engines. The method is applied to a model aircraft fitted with two model engines similar to GE90 115B to test the feasibility of the method with one engine degraded and the other engine undegraded. The obtained results demonstrate that for the aircraft flying between London and Toronto with 5,000 nominal flight cycles given to the engines, the time on-wing of the degraded engine could drop from 5,000 to 2,460 flight days due to its HP turbine degradation (1% efficiency degradation 3% flow capacity degradation), causing the same level of drop of time between overhaul of the aircraft. The time on-wing of the degraded engine could increase from 2,460 flight days without thrust rebalance to 3,410 flight days with thrust rebalance, i. e. around 38.6% potential improvement for the time between overhaul of the aircraft at the expenses of increased creep life consumption rate of the clean engine. The proposed method could be applied to other aircraft and engines.

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Section: Gas Turbine Performance Modelmentioning

confidence: 99%

Thrust Rebalance to Extend Engine Time On-Wing With Consideration of Engine Degradation and Creep Life Consumption

Chiavegatto,

2024

Journal of Engineering for Gas Turbines and Power

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“…Zhou et al [25] calculated the combined effect of creep and fatigue on the first turbine stage of a power-generation gas turbine engine using the Larson-Miller Parameter and stress-life curve for the two damage mechanisms, respectively. Alozie et al [26] translated the effect of fouling and erosion on an HPT to an equivalent time that the engine would have to operate in a reference mission to suffer the same degradation as when exposed to desert sand.…”

Section: Performance-based Gas Turbine Lifing Studiesmentioning

confidence: 99%

Hot Corrosion Damage Modelling in Aero Engines based on Performance and Flight Mission Analysis

Pontika

Laskaridis

Nikolaidis

et al. 2023

AIAA SCITECH 2023 Forum

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Lifing models for aircraft engines are mainly focused on creep, fatigue and oxidation, while hot corrosion remains one of the least explored areas. Hot corrosion is a form of chemical damage that causes surface degradation, sound material loss and reduced component life. A lifing analysis for aircraft engines without considering hot corrosion can lead to unexpected and unexplained hot corrosion findings by aircraft engine operators and Maintenance, Repair and Overhaul (MRO) providers during inspections. Although hot corrosion does not cause failure on its own, the interaction with other damage mechanisms can reduce component life significantly. Consequently, there is a necessity for including hot corrosion in the damage prediction process of aircraft engines. This paper presents a new methodology to estimate hot corrosion damage based on aero-engine performance and flight mission analysis while taking into account environmental exposure, fuel quality and material factors. The analysis in the present paper focuses on the hot corrosion progress over the course of the flight mission, while varying the major contamination factors and thrust derate, and the hot corrosion rate over flight time is then used to calculate the damage at the end of the mission. The participating mechanisms, from salt and sulfur impurity ingestion to deposition rate and hot corrosion attack, are analytically presented to explain the progress of the phenomenon in aero-engine components. In the investigated type of engine, the first stage of the low-pressure turbine is found to be the most affected. It is concluded that hot corrosion is favored by a combination of high pressure, high sulfur oxide concentration, and high salt deposition rate within an intermediate temperature range while the gas conditions near the component surface remain below the sodium sulfate saturation point, and these conditions are linked with aero-engine operation. The presented hot corrosion framework captures the effect of mission requirements, component operating conditions, environmental exposure, fuel quality and material on the hot corrosion damage of hot section components. It can be used to inform aero-engine maintenance planning, lifecycle analysis and MRO contract-costing, and can benefit digital twins for predictive maintenance.

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“…The values of exponent magnitudes for the first, second, and third stages of the compressor are 2.5, 2.8571, and 2.3333, respectively. Alozie et al [49] reported a novel "equivalent operating time (EOT)" model that considers fouling, erosion, and blade-tip wear to determine the degradation rate of the turbine engine with respect to a pre-defined reference condition. It was concluded that the model perfectly predicts the component degradation and its remaining service life.…”

Section: Erosion Of Compressor Blades By Sand Particlesmentioning

confidence: 99%

High-Temperature Solid Particle Erosion of Aerospace Components: Its Mitigation Using Advanced Nanostructured Coating Technologies

Bonu¹,

Barshilia²

2022

Coatings

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Solid particle erosion of gas turbine blades in the aerospace sector results in increased maintenance costs, high pollution, reduced engine efficiency, etc. Gas turbines in aircraft are usually operated at high temperatures. Based on the compressor stage, the temperature varies from 100–600°C, whereas turbine blades, after combustion, experience a very high temperature between 1000–1400 °C. So, a better understanding of temperature-dependent solid particle erosion is required to develop suitable solid particle erosion-resistant coatings for gas turbine blades. In this review, a detailed overview of the effect of temperature on the solid particle erosion process and different types of erosion-resistant coatings developed over the last four decades for compressor blades are discussed in detail. In the initial sections of the paper, solid particle erosion mechanisms, erosion by different erodent media, and the influence of erosion on gas turbine engines are discussed. Then, the erosion rate trend with increasing temperature for ductile and brittle materials, high-temperature erosion tests in a corrosive environment, and the role of oxidation and bonding nature in high-temperature erosion are examined. In most cases, the erosion rate of materials decreased with increasing temperature. After this, the evolution of erosion-resistant coatings over the last four decades that are first-generation (single-phase coatings), second-generation (metal/ceramic multilayer coatings), and third-generation (nanocomposite and nano-multilayer coatings) erosion-resistant coatings are reviewed in detail. The third-generation nano coatings were found to be superior to the first- and second-generation erosion-resistant coatings. Finally, some of the commercial or notable erosion-resistant coatings developed in the last decade are discussed. The paper concluded with the research gaps that need to be addressed to develop efficient erosion-resistant coatings.

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Assessment of degradation equivalent operating time for aircraft gas turbine engines

Cited by 13 publications

References 32 publications

Thrust Rebalance to Extend Engine Time On-Wing With Consideration of Engine Degradation and Creep Life Consumption

Thrust Rebalance to Extend Engine Time On-Wing With Consideration of Engine Degradation and Creep Life Consumption

Hot Corrosion Damage Modelling in Aero Engines based on Performance and Flight Mission Analysis

High-Temperature Solid Particle Erosion of Aerospace Components: Its Mitigation Using Advanced Nanostructured Coating Technologies

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