• Title/Summary/Keyword: Steam Turbine Blade

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A 3-Dimentional Finite-Element Vibration Analysis of Blade Groups for Steam Turbines (증기 터빈 블레이드 그룹의 3차원 유한요소 진동 해석)

  • 서자력;류석주;박종포
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.05a
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    • pp.729-734
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    • 2001
  • A 3-dimentional finite element model for vibration analysis of steam-turbine blade groups is presented, employing the 3-dimentional incompatible brick element with 8 nodes. The skew coordinate system is introduced in the model for considering multi-axis symmetry and specialty of displacement constrain condition of blade groups. Vibration characteristics of blade groups are analyzed, and compared with experimental results.

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Numerical investigation of LP turbine-exhaust hood interaction in the steam turbine exhaust system (스팀터빈 Exhaust System에서 LP터빈과 Exhaust Hood 사이의 간섭에 대한 수치해석적 연구)

  • Im, Ji-Hyun;Joo, Won-Gu;Kim, Young-Sang;Im, Hong-Sik
    • 유체기계공업학회:학술대회논문집
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    • 2006.08a
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    • pp.291-294
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    • 2006
  • Exhaust system of steam turbines consists of an annular diffuser and a collector and connects the last stage turbine and the condenser. The system is used to transfer the turbine leaving kinetic energy to potential energy while guiding the flow from turbine exit plane to the downstream condenser. In the steam turbine exhaust system, distorted pressure profile is arisen by the nonaxisymmetric collector structure at the diffuser outlet, and this distorted pressure is propagated to the last stage LP turbine exit plane through the diffuser, then the last stage LP turbine experiences asymmetric back pressure. It is known that the pressure recovery performance of diffuser is strongly influenced by diffuser inflow condition. In this study, the effect of exhaust system due to the changing of inlet flow condition is observed by using CFD, and the interaction of last stage LP turbine and exhaust system is investigated by using actuator disk model as modeling of turbine blade row of exhaust hood inlet.

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A Study on the X-Ray Fractography of Turbine Blade under Fatigue Load (피로하중을 받는 터빈 블레이드의 X선 프랙토그래픽에 관한 연구)

  • Hong, Soon-Hyeok;Lee, Dong-Woo;Cho, Seok-Swoo;Joo, Won-Sik
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.2
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    • pp.65-71
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    • 2002
  • Turbine blade is subject to cyclic bending force by steam pressure. Stress analysis by fractography is already established technology as means far seeking cause of fracture and has been widely employed. In the X-ray frctography, plastic deformation and residual stress near the fracture surface can be determined and information of internal structure of material can be obtained. Therefore, to find a fracture mechanism of torsion-mounted blade in nuclear power plant, based on the information from the fracture surface obtained by fatigue test, the correlation of X-ray parameter and fracture mechanics parameter was determined and then the stress intensity factor to actual broken turbine blade was predicted.

A Study on the X-Ray Fractography of Turbine Blade under Fatigue Load (피로하중을 받는 터빈 블레이드의 X선의 프랙토그래피에 관한 연구)

  • 김성웅;이동우;홍순혁;조석수;주원식
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.778-783
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    • 2001
  • Turbine blade is subject to cyclic bending force by steam pressure. Stress analysis by fractography is already established technology as means for seeking cause of fracture and has been widely employed. In the X-ray fractography, plastic deformation and residual stress near the fracture surface can by determined and information of internal structure of material can be obtained. Therefore, to find a fracture mechanism of torsion-mounted blade in nuclear power plant, based on the information from the fracture surface obtained by fatigue test, the correlation of X-ray parameter and fracture mechanics parameter was determined and then the load applied to actual broken turbine blade was predicted.

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Methodology for Centrifugal Stress Estimation Model Development of Large Steam Turbine Blades (스팀 터빈 블레이드 원심응력 추정을 위한 전산해석 연구)

  • Lee, Byounghak;Park, Jongho
    • The KSFM Journal of Fluid Machinery
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    • v.16 no.6
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    • pp.26-31
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    • 2013
  • Last blades of low-pressure turbine in nuclear power plant are the highly damaged part and always suffered from different types of loadings leading to various stress components, stresses due to centrifugal force and steam flow loading. Especially, centrifugal stress generated by turbine rotation is one of the main problems and more significant than other stresses as they have the greatest effect on total stress. Therefore, this study was performed to obtain the important information for estimation model development of the blade centrifugal stress level and distribution.

A Study on Electrochemical Evaluation Method of Toughness Degradation for 12%Cr Steel (II) (12%Cr강 인성열화도의 전기화학적 평가법에 대한 연구(II))

  • Kim, Chang-Hui;Seo, Hyun-Uk;Yoon, Kee-Bong;Park, Ki-Sung;Kim, Seoung-Tae
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.268-273
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    • 2001
  • Fossil power plants operated in high temperature condition are composed of components such as turbine, boiler, and piping system. Among these components, turbine blades made with 12%Cr steel operate at a temperature above $500^{\circ}C$. Due to the long term service, turbine blades experience material degradation manifested by change in mechanical and microstructural properties. The need to make life assessment and to evaluate material degradation of turbine blade is strongly required but in reality, there is a lack of knowledge in defining failure mechanism and fundamental data for this component. Therefore, in making life assessment of turbine blade, evaluation of material degradation must be a priority. For this purpose, evaluation of toughness degradation is very important. The major cause of toughness degradation in 12Cr turbine blade is reported to be critical corrosion pitting induced by segregation of impurity elements(P etc.), coarsening of carbide, and corrosion, but the of materials for in-service application. In this study, the purpose of research is focused on evaluating toughness degradation with respect to operation time for 12%Cr steel turbine blade under high temperature steam environment and quantitatively detecting the degradation properties which is the cause of toughness degradation by means of non-destructive method, electrochemical polarization.

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A Study on the Failure Mechanism of Turbine Blade using X-Ray Diffraction and FEM (X선 회절과 유한요소법을 이용한 터빈 블레이드의 파괴기구에 관한 연구)

  • Kim, Seong-Ung;Hong, Sun-Hyeok;Jeon, Hyeong-Yong;Jo, Seok-Su;Ju, Won-Sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.8
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    • pp.1645-1652
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    • 2002
  • The failure analysis on fractured parts is divided into the qualitative method by naked eyes and metallurgical microscope etc. and the quantitative method by SEM and X-ray diffraction etc. X-ray fractography can be applied to contaminated surface as well as clean surface and gain the plastic deformation and the residual stress near the fractured surface. Turbine blade is subject to cyclic bending force by steam pressure and suffers fatigue damage according to the increasing operating time. Therefore, to clean up the fracture mechanism of torsion-mounted blade in nuclear plant, the fatigue and the X-ray diffraction test was performed on the 12%Cr steel fur turbine blade and the fractured parts. The correlation of X-ray parameter and fracture mechanics parameter was determined, and then the load applied to actual broken turbine blade was predicted. Failure analysis was performed by contact stress analysis and Goodman diagram of torsion-mounted blade.

Vibration Characteristics and Analysis of the Critical Crack Length for a Fracture in the Last Stage Blade of a Low Pressure Steam Turbine (균열을 내재한 저압터빈 최종단 블레이드의 진동 특성 및 파괴 임계균열길이 해석)

  • Youn, Hee-Chul;Woo, Chang-Ki;Rhee, Zhang-Kyu
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.25 no.5
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    • pp.386-392
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    • 2016
  • The sizes of last stage blades (LSB) in a low-pressure steam turbine have been getting larger for the development of high-capacity power plants. They are also larger than other blades in the same system. As a result, crack propagation in an LSB is caused by the large centrifugal force, low natural frequency, and repeated turbine startups. In this study, the critical crack length for a fracture and vibration characteristics, in accordance with crack propagation, were analyzed using a finite element method to calculate the stress intensity factor (SIF) and the natural frequency that was affected by the stress-stiffening effect. It was calculated that the frequency of the third and fifth modes passed the excited harmonic resonance (5X and 10X) and the observed calculated critical crack length matched that of the real fractured surface.

A Stochastic Analysis in Fatigue Strength of Degraded Steam Turbine Blade Steel (열화된 증기 터빈블레이드의 피로강도에 대한 확률론적 해석)

  • Kim, Chul-Su;Jung, Hwa-Young;Kim, Jung-Kyu
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.262-267
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    • 2001
  • In this study, the Reliability of degraded steam turbine blade was evaluated using the limited fatigue data. The statistical estimation of limited fatigue data implies that some unknown uncertainties which may be involved in fatigue reliability analysis. Therefore, an appropriate distribution in the fatigue strength was determined by the characteristic distribution - linear correlation coefficient, fatigue physics, error parameter. 3-parameter Weibull distribution is the most appropriate distribution to assume for infinite region. The load applied on the blade is mainly tensile. The maximum Von-Mises stress is 219.4 MPa at the steady state service condition. The failure probability($F_p$) derived from the strength-stress interference model using Monte carlo simulation under variable service condition is 0.25% at the 99.99% confidence level.

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Study on the Surface Coating of CrN for Erosion in Liquid water Drop Test

  • Kwon, Sik-Chol;Baek, W-S;Lee, S-H;Kim, K-H;Kim, H-H
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2001.11a
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    • pp.63-63
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    • 2001
  • As a new approach to substitute for a hard alloy of stellite 6B containing Co which is radioactive in nuclear system, a hard-phase coating of CrN will be applicable to protect 12Cr steel from erosion at leading edge on steam turbine blade. The CrN coating was prepared by arc ion plating on 12 Cr steel and was undertaken in liquid impact test at the velocity of 35Om/sec, which simulate the environment in the last stage of blade. The erosion resistance of coating was evaluated by optical observation on damaged surface. The threshold number of impact was closely related with surface hardness. And thus, it was confirmed that surface hardening improves the life time of steam turbine blade.

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