scholarly journals Dynamics of a Turbine Blade with an Under-Platform Damper Considering the Bladed Disc’s Rotation

2019 ◽  
Vol 9 (19) ◽  
pp. 4181 ◽  
Author(s):  
Shangwen He ◽  
Wenzhen Jia ◽  
Zhaorui Yang ◽  
Bingbing He ◽  
Jun Zhao
Keyword(s):  
Turbine Blade ◽  
High Cycle Fatigue ◽  
Turbine Blades ◽  
Cycle Fatigue ◽  
Aero Engine ◽  
Aero Engines

High-cycle fatigue (HCF) failure of the turbine blades of aero-engines caused by high vibrational stresses is one of the main causes of aero-engine incidents [...]

High-Cycle Fatigue Design Evolution and Experience of Free-Standing Combustion Turbine Blades

1992 ◽  
Vol 114 (2) ◽  
pp. 284-292 ◽  
Author(s):  
A. J. Scalzo
Keyword(s):  
Turbine Blade ◽  
High Cycle Fatigue ◽  
Turbine Blades ◽  
Design Criteria ◽  
Cycle Fatigue ◽  
Free Standing ◽  
Fatigue Design ◽  
Turbine Blade Design ◽  
Westinghouse Electric ◽  
Cooling Air

Combustion turbine blade design criteria can generally be classified as either temperature or fatigue related. Since less is usually known about the factors influencing the fatigue phenomenon, it is considered the more challenging. In addition, as analytical and experimental techniques became more sophisticated and more accurate, the natural tendency was to replace archaic “guidelines” or “rules” with less conservative approaches that at times led to the discovery of new high-cycle fatigue “thresholds.” This paper presents the evolution of the combustion turbine blade high cycle fatigue design criteria for free-standing blades. It also presents the analysis and corrective actions taken to resolve several unique combustion turbine blade fatigue problems, all encountered over a 35-year period while the author has been employed at Westinghouse Electric Corporation. Included are high-cycle fatigue problems due to cooling air leakage, seal pin friction, and combustion temperature maldistribution, as well as flow-induced nonsynchronous vibration.

scholarly journals High-Cycle Fatigue Design Evolution and Experience of Freestanding Combustion Turbine Blades

1991 ◽  
Author(s):  
A. J. Scalzo
Keyword(s):  
Turbine Blade ◽  
High Cycle Fatigue ◽  
Turbine Blades ◽  
Design Criteria ◽  
Cycle Fatigue ◽  
Design Evolution ◽  
Fatigue Design ◽  
Turbine Blade Design ◽  
Westinghouse Electric ◽  
Cooling Air

Combustion turbine blade design criteria can generally be classified as either temperature or fatigue related. Since less is usually known about the factors influencing the fatigue phenomenon, it is considered the more challenging. In addition, as analytical and experimental techniques became more sophisticated and more accurate, the natural tendency was to replace archaic “guidelines” or “rules” with less conservative approaches that at times led to the discovery of new high cycle fatigue “thresholds”. This paper presents the evolution of the combustion turbine blade high cycle fatigue design criteria for freestanding blades; and, also presents the analysis and corrective actions taken to resolve several unique combustion turbine blade fatigue problems, all encountered over a thirty-five year period while the author has been employed at Westinghouse Electric Corporation. Included are high-cycle fatigue problems due to cooling air leakage, seal pin friction, combustion temperature maldistribution, as well as flow-induced nonsynchronous vibration.

Life Prediction Modeling of Combined High-Cycle Fatigue and Creep

2020 ◽  
Author(s):  
Thomas Bouchenot ◽  
Kirtan Patel ◽  
Ali P. Gordon ◽  
Sachin Shinde
Keyword(s):  
Prediction Model ◽  
Turbine Blade ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Prediction Models ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Test Method ◽  
Cycle Fatigue ◽  
Life Prediction Model

Abstract Industrial gas turbine blades are subjected to high temperatures and an array of mechanical and dynamic loads, making creep and high-cycle fatigue critical aspects of turbine blade design. The combination of creep and high-cycle fatigue produces a synergistic interaction effect whose explicit consequence to turbine life has been the subject of very little research. This interaction remains unaccounted for by current, decoupled life prediction models, which traditionally incorporate such interactions into conservative design safety factors. Improved lifing models capable of capturing these effects are now needed in order to maintain current reliability standards in next-generation operating conditions. This research identifies the life-limiting aspect of a combined high-cycle fatigue and creep response in conventionally cast Alloy 247 LC, and captures the interaction of the two loads in a novel life prediction model. The proposed model is created from a comprehensive collection of experimental data obtained using an unconventional two-part test method, where test specimens pre-deformed to a prescribed creep strain are fatigue loaded at an elevated temperature and high frequency until failure. A variety of temperatures, creep strains, and fatigue loading conditions are explored to ensure that the resulting model is applicable to the myriad of potential turbine blade operating conditions. Rigorous metallographic assessments accompanying each test are leveraged to create a microstructurally-informed combined life prediction model.

Effect of Aluminized Coating on Combined Low and High Cycle Fatigue Life of Turbine Blade at Elevated Temperature

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Cao Chen ◽  
Xiaojun Yan ◽  
Xiaoyong Zhang ◽  
Yingsong Zhang ◽  
Min Gui ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Crack Initiation ◽  
Turbine Blade ◽  
High Cycle Fatigue ◽  
Turbine Blades ◽  
Cycle Fatigue ◽  
Σ Phase ◽  
Initiation And Propagation ◽  
Crack Initiation Life

Some cracks were detected on the fir-tree root of turbine blade in an in-service aero-engine, and the aluminized coating was considered to be the main cause of these cracks. To study the effect of aluminized coating on fatigue life of turbine blade, the combined low and high cycle fatigue (CCF) tests are carried out at elevated temperature on both aluminized and untreated turbine blades. Probability analysis of test data is conducted and the result indicates that the median life is decreased by 62.2% due to the effect of the aluminized coating. Further study on the mechanism of crack initiation and propagation has been conducted based on fractography and cross section morphology analysis by using scanning electron microscope (SEM), and the results indicate: (1) The aluminized coating consists of two layers, of which the inner layer is considered to contain the σ phase and it reduces the resistance to fatigue of blade. (2) Many cavities are found in the inner layer of aluminized coating, which lead to the initiation of cracks and result in the reduction of crack initiation life. (3) The marker band widths of aluminized and untreated blade are very close, which indicated the aluminized coating may have no effect on the crack propagation life of the blade.

A New Modified Contrast Method for Life Prediction in Combined Cycle Fatigue Test

2017 ◽  
Author(s):  
Lei Han ◽  
Cao Chen ◽  
Xiaoyong Zhang ◽  
Xiaojun Yan
Keyword(s):  
Turbine Blade ◽  
High Cycle Fatigue ◽  
Aerodynamic Force ◽  
Low Cycle Fatigue ◽  
Fracture Morphology ◽  
Combined Cycle ◽  
Full Scale ◽  
Cycle Fatigue ◽  
Contrast Method ◽  
Ultra High Cycle Fatigue

The combined high and low cycle fatigue (CCF) test on full scale turbine blade in the laboratory is an important method to evaluate the life. In fact, the low cycle fatigue which is usually caused by the centrifugal force can be confirmed easily. While, the high cycle fatigue which is usually caused by the vibration and aerodynamic force is often hard to determine. So the previous scholar has proposed the contrast method to determine the high cycle load in the field. This method utilizes the new and used blades to determine the high cycle within certain limits. While it can’t be applied effectively in the whole life range with the low cycle-high cycle-ultra high cycle fatigue theory raised. So this paper put forward the modified contrast method to realize the optimization. Firstly, the CCF tests are carried out on the turbine blade systematically. Then, the CCF damage properties, including the crack propagation, the fracture morphology and the dynamic characteristic are analyzed. Lastly, the new modified contrast method is proposed with the new coordinate axes, new fitting criterions and amend method. Through comparisons we conclude that: the new method is slightly complicated, but the evaluate precision has significantly increased. So it could be used to deal with data for CCF tests on full scale turbine blade in the future.

Aeroelastic Analysis of NREL Wind Turbine

2017 ◽  
Author(s):  
Yaozhi Lu ◽  
Fanzhou Zhao ◽  
Loic Salles ◽  
Mehdi Vahdati
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Gas Turbines ◽  
High Cycle Fatigue ◽  
Turbine Blades ◽  
Measured Data ◽  
Forced Response ◽  
Cycle Fatigue ◽  
Aeroelastic Analysis

The current development of wind turbines is moving toward larger and more flexible units, which can make them prone to fatigue damage induced by aeroelastic vibrations. The estimation of the total life of the composite components in a wind turbine requires the knowledge of both low and high cycle fatigue (LCF and HCF) data. The first aim of this study is to produce a validated numerical model, which can be used for aeroelastic analysis of wind turbines and is capable of estimating the LCF and HCF loads on the blade. The second aim of this work is to use the validated numerical model to assess the effects of extreme environmental conditions (such as high wind speeds) and rotor over-speed on low and high cycle fatigue. Numerical modelling of this project is carried out using the Computational Fluid Dynamics (CFD) & aeroelasticity code AU3D, which is written at Imperial College and developed over many years with the support from Rolls-Royce. This code has been validated extensively for unsteady aerodynamic and aeroelastic analysis of high-speed flows in gas turbines, yet, has not been used for low-speed flows around wind turbine blades. Therefore, in the first place the capability of this code for predicting steady and unsteady flows over wind turbines is studied. The test case used for this purpose is the Phase VI wind turbine from the National Renewable Energy Laboratory (NREL), which has extensive steady, unsteady and mechanical measured data. From the aerodynamic viewpoint of this study, AU3D results correlated well with the measured data for both steady and unsteady flow variables, which indicated that the code is capable of calculating the correct flow at low speeds for wind turbines. The aeroelastic results showed that increase in crosswind and shaft speed would result in an increase of unsteady loading on the blade which could decrease the lifespan of a wind turbine due to HCF. Shaft overspeed leads to significant increase in steady loading which affects the LCF behaviour. Moreover, the introduction of crosswind could result in significant dynamic vibration due to forced response at resonance.

The Effect of Foreign Object Damage on Compressor Blade High Cycle Fatigue Strength

2017 ◽  
Author(s):  
Benjamin Hanschke ◽  
Thomas Klauke ◽  
Arnold Kühhorn
Keyword(s):  
Fatigue Strength ◽  
Service Sector ◽  
High Cycle Fatigue ◽  
Compressor Blade ◽  
Foreign Object ◽  
Cycle Fatigue ◽  
Stress Concentrations ◽  
Foreign Object Damage ◽  
Input Parameters ◽  
Aero Engines

For a considerable amount of time blade integrated disks (blisks) are established as a standard component of high pressure compressors (HPCs) in aero engines. Due to the steady requirement to increase the efficiency of modern HPCs, blade profiles get thinned out and aerodynamic stage loading increases. Ever since, aerofoil design has to balance structural and aerodynamic requirements. One particularity of aero engines is the possibility to ingest different kinds of debris during operation and some of those particles are hard enough to seriously damage the aerofoil. Lately, a growing number of blisk-equipped aero engines entered service and the question of foreign object damage (FOD) sensitivity relating to compressor blade high cycle fatigue (HCF) has emerged. Correct prediction of fatigue strength drop due to a FOD provides a huge chance for cost cutting in the service sector as on-wing repairs (e.g. borescope blending) are much more convenient than the replacement of whole blisks and corresponding engine strips. The aim of this paper is to identify critical FOD-areas of a modern HPC stage and to analyze the effects of stress concentrations — caused by FOD — on the fatigue strength. A process chain has been developed, that automatically creates damaged geometries, meshes the parts and analyses the fatigue strength. Amplitude frequency strength (af-strength) has been chosen as fatigue strength indicator owing to the fact, that amplitudes and frequencies of blade vibrations are commonly measured either by blade tip timing or strain gauges. Furthermore, static and dynamic stress concentrations in damaged geometries compared to the reference design were computed. A random variation of input parameters was performed, such as the radial damage position at blade leading edge and damage diameter. Based on results of the different samples, correlations of input parameters and the fatigue strength drop have been investigated. Evaluation shows a significant mode dependence of critical blade areas with a large scatter between drops in fatigue strength visible for mode to mode comparison. Keeping in mind the necessity of fast response times in the in-service sector, FOD sensitivity computations could be performed for all blade rows of the HPC — including the analysis of possible borescope blending geometries — in the design stage. Finally, the actual amplitude frequency levels (af-levels) of the modes excited during operation have to be appropriately taken into consideration. For example, a pronounced af-strength drop due to a FOD may not be critical for safe engine operations because the observed mode is excited by small af-levels during operation. Hence, the endurance ratio — a quotient of af-level and af-strength — is used as assessment criterion.

Behavior of a Variable Geometry Turbine Wheel to High Cycle Fatigue

2020 ◽  
Author(s):  
Calogero Avola ◽  
Alberto Racca ◽  
Angelo Montanino ◽  
Carnell E. Williams ◽  
Alfonso Renella ◽  
...  
Keyword(s):  
High Cycle Fatigue ◽  
Combustion Engine ◽  
Turbine Blades ◽  
Variable Geometry ◽  
Cycle Fatigue ◽  
Turbine Stage ◽  
Turbine Wheel ◽  
Variable Geometry Turbine ◽  
Turbine Design ◽  
Mechanical Optimization

Abstract Maximization of the turbocharger efficiency is fundamental to the reduction of the internal combustion engine back-pressure. Specifically, in turbochargers with a variable geometry turbine (VGT), energy losses can be induced by the aerodynamic profile of both the nozzle vanes and the turbine blades. Although appropriate considerations on material limits and structural performance of the turbine wheel are monitored in the design and aero-mechanical optimization phases, in these stages, fatigue phenomena might be ignored. Fatigue occurrence in VGT wheels can be categorized into low and high cycle behaviors. The former would be induced by the change in turbine rotational speed in time, while the latter would be caused by the interaction between the aerodynamic excitation and blades resonating modes. In this paper, an optimized turbine stage, including unique nozzle vanes design and turbine blades profile, has been assessed for high cycle fatigue (HCF) behavior. To estimate the robustness of the turbine wheel under several powertrain operations, a procedure to evaluate HCF behavior has been developed. Specifically, the HCF procedure tries to identify the possible resonances between the turbine blades frequency of vibrations and the excitation order induced by the number of variable vanes. Moreover, the method evaluates the turbine design robustness by checking the stress levels in the component against the limits imposed by the Goodman law of the material selected for the turbine wheel. In conclusion, both the VGT design and the HCF approach are experimentally assessed.

Plastic Effects on High Cycle Fatigue at the Edge of Contact of Turbine Blade Fixtures

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
C. H. Richter ◽  
U. Krupp ◽  
M. Zeißig ◽  
G. Telljohann
Keyword(s):  
Finite Element Analysis ◽  
High Cycle Fatigue ◽  
Turbine Blades ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Notched Specimens ◽  
The Finite Element Analysis ◽  
Slip Region ◽  
Good Agreement

Slender turbine blades are susceptible to excitation. Resulting vibrations stress the blade's fixture to the rotor or stator. In this paper, high cycle fatigue at the edge of contact (EOC) between blade and rotor/stator of such fixtures is investigated both experimentally and numerically. Plasticity in the contact zone and its effects on, e.g., contact tractions, fatigue determinative quantities, and fatigue itself are shown to be of considerable relevance. The accuracy of the finite element analysis (FEA) is demonstrated by comparing the predicted utilizations and slip region widths with data gained from tests. For the evaluation of EOC fatigue, tests on simple notched specimens provide the limit data. Predictions on the utilization are made for the EOC of a dovetail setup. Tests with this setup provide the experimental fatigue limit to be compared to. The comparisons carried out show a good agreement between the experimental results and the plasticity-based calculations of the demonstrated approach.

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