Journal of the Korean Society of Manufacturing Technology Engineers (한국생산제조학회지)

The Korean Society of Manufacturing Technology Engineers (한국생산제조학회)
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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 (Department of Mechanical Engineering, Incheon National University) ;
  • Woo, Chang-Ki (Department of Mechanical Engineering, Incheon National University) ;
  • Rhee, Zhang-Kyu (Department of Mechatronics Engineering, Yuhan University)
  • Received : 2016.08.05
  • Accepted : 2016.09.29
  • Published : 2016.10.15
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Abstract

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.

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References

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