Failure analysis of the final stage blade in steam turbine

Wang, Weize; Xuan, Fu‐Zhen; Zhu, Kui-Long; Tu, Shan‐Tung

doi:10.1016/j.engfailanal.2006.03.004

Cited by 48 publications

(20 citation statements)

References 3 publications

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“…Some examples of blade release investigations may be found in [1][2][3][4][5][6]. Evaluation of the root cause is assisted through usage of the EDS technique, helping understanding of the evolution of the crack with time.The EDS technique and fundamentals is described in [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Energy Dispersive X-ray technique applied to fatigue fracture surfaces oxidation to provide information on growth rate

Hernandez¹,

Saunders

Madariaga³

2018

MATEC Web Conf.

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Abstract. Gas turbine components are strongly affected by cyclic loading during operation, which makes fatigue development the most significant cause of failure or cracking within them. The nature and growth rate of that fatigue is dependent on the stress experienced at a particular area of a part, the temperature, the material properties and the applied loading frequency. Various techniques, such as striation and/or band counting can, in some cases, provide information on fatigue life. However, often such techniques are rendered useless by lack of formation or obliteration by damage and/or oxidation of such features. Once a crack has initiated and is exposed to the engine atmosphere, the level of oxidation and other contaminant elements observed on the crack surface will evolve with time, and, correspondingly, crack depth. Element distribution analysis by an Energy Dispersive x-ray Spectroscopy (EDS) technique applied along a fatigue fracture surface could help to understand the evolution of the crack with time.Using EDS, an experimental procedure was carried out to ascertain a perceived measured percentage of oxygen plus other additional chemical species at a large number of stations along the length of a fatigue crack. The analysis was performed from the initiation site to the end of the propagation area, and also within the final rupture zone which had less time exposed to air and gasses compared to the fatigue system. An exercise of comparison between that progression in oxidation across cracked in-service components versus perceived measured oxidation level analyses on trial fracture surfaces exposed in atmospheric oven conditions at high temperatures for a number of different durations was performed. The obtained results provided information on specific questions concerning the fatigue propagation life of the in-service components; thereby amplifying the use of the EDS technique in this aspect of the materials forensic field.

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Section: Introductionmentioning

confidence: 99%

Energy Dispersive X-ray technique applied to fatigue fracture surfaces oxidation to provide information on growth rate

Hernandez¹,

Saunders

Madariaga³

2018

MATEC Web Conf.

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“…Water droplets after condensation deposit mainly on the trailing edges of the stator blades and then are swept off the trailing edges by the incoming expanding steam flow, see Wang et al, (2007) and Martinez et al, (2011). Relatively large, characterized with low velocity, water droplets hit the leading edge of rotor blades, Azevedo and Sinatora (2009).…”

Section: Introductionmentioning

confidence: 99%

“…Both the erosion and deposition phenomenon change the surface finish; stationary and rotating blade flow areas; alter the shape of leading and trailing edges (Wang et al, (2007) and Azevedo and Sinatora (2009), increase the blade surface roughness (Martinez et al, (2011), A. CamposAmezcua et al, (2007 and introduce irregularities in the steam path, resulting in eddies generation with losses these eddies produce, see Atrens et al, (1983), Azevedo and Sinatora (2009), White (1992), Vishvanathan (1989), Ansari (1986) and Springer (1976).…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Water Droplets Deposition on Turbine Blade Surfaces and Erosion Wear Effects

Ilieva¹

2017

JAFM

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Failure of turbine blades leads to various exploitation problems, efficiency decrease and economical losses, at all. A detailed research on aerodynamic features, in various exploitation conditions and regimes, and on reasons for failures, is a prerequisite to the obviated technical problems and increased reliability of turbine aggregates. Water droplets erosion is known as a very complex and crucial phenomena. It couples the effects of wet steam expansion, together with condensation (evaporation), presence of second phase with the impact of water droplets over blade surfaces, erosion effects and fatigue mechanisms. The present research deals with a logical sequence for numerical simulations and research on erosion mechanisms in a low pressure stage of К-1000-6 /1500 steam turbine, working at a Nuclear Power Plant. Attention is paid to the impact of droplets' diameter on blade surfaces, their aerodynamic behavior and efficiency of energy conversion through turbine channels. Particular trajectories of water droplets, reasons for occurrence of erosion wear, over certain parts of the streamlined surfaces, are established and discussed. An approach to acquire incidence time to erosion appearance is implemented. Research methodology and obtained results are applicable to determine erosion effects on streamed complex surfaces, to replace expensive measurements campaigns, introduce approaches to decrease wetness in last stages of condensation turbines and prolong the reliability of blades operated in wet steam conditions

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“…The later stages of the low pressure turbines have been shown to be more susceptible to fatigue damage [2] due to the increased blade lengths resulting in increased stress levels and allowing for a multitude of possible resonances. Various instances of low pressure steam turbine blade failures have been reported in [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Fatigue life assessment of a low pressure steam turbine blade during transient resonant conditions using a probabilistic approach

Booysen

Heyns

Hindley

et al. 2015

International Journal of Fatigue

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Failure analysis of the final stage blade in steam turbine

Cited by 48 publications

References 3 publications

Energy Dispersive X-ray technique applied to fatigue fracture surfaces oxidation to provide information on growth rate

Energy Dispersive X-ray technique applied to fatigue fracture surfaces oxidation to provide information on growth rate

Mechanisms of Water Droplets Deposition on Turbine Blade Surfaces and Erosion Wear Effects

Fatigue life assessment of a low pressure steam turbine blade during transient resonant conditions using a probabilistic approach

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