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증기터빈 로터 중심공 묻힘 결함에 대한 해석적 수명 평가 기준 제시
황미경(Mikyung Hwang),조기현(Kihyun Cho) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
The steam turbine rotor receives a radial temperature gradient when starting up and shutting down of the turbine, and fatigue and creep damage occur depending on the operation condition. Reliable steam turbine operation is necessary for stable power supply and as a basis for this, power generation companies are required to perform the life assessment for structural integrity in Article 32 of ELECTRIC UTILITY ACT. However, it is difficult to apply a standardized guideline because this criterion for the remaining life evaluation are based on the contract partners own standards. In this study, in order to provide the reliable life assessment method of steam turbines, heat transfer, and stress analysis and fracture mechanics based life assessment is performed on the high-pressure rotor bore. The results of the evaluation were verified by comparing SAFER-PC, Rotor Life Assessment Program, developed by Electric Power Research Institute (EPRI).
로터 보어 단순 열응력 해석 모델 이용한 확률론적 피로 수명 계산
이동민(Dongmin Lee),김정언(Chungeon Kim),오현석(Hyunseok Oh),황미경(Mikyung Hwang),조기현(Kihyun Cho) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
본 논문에서는 단순 열응력 해석을 이용한 로터 보어의 확률론적 수명 평가 가능성을 파악하고자 한다. 증기 터빈 로터 보어의 온도 및 응력 공간 분포를 결정하기 위해 간단한 열 응력 해석을 수행한다. 열응력 해석 결과를 기반으로, 최대 응력 지점에 표면 균열을 삽입한다. 결정론적 파괴역학 해석 결과를 이용하여 로터 보어 피로 수명을 계산한다. 뿐만 아니라, 로터 보어의 피로 수명을 확률론적으로 평가하기 위해 몬테카를로 시뮬레이션을 이용하여 불확실성 전파를 수행한다. 불확실성 인자는 Paris 매개변수 C 와 m으로 가정한다. 최종적으로 로터 보어의 확률론적 수명 분포를 추정한다. In this work, the feasibility of probabilistic life assessment for rotor bores is examined by simple thermal stress analysis. A simple thermal stress analysis is conducted to determine the spatial distribution of temperature and stress of the rotor bore in steam turbines. Based on the result from the thermal stress analysis, a surface crack is seeded at the spot with the maximum stress. The fatigue life of the rotor bore with the seeded crack is calculated by the fracture mechanics analysis in a deterministic manner. To evaluate the fatigue life of the rotor bore in a probabilistic manner, uncertainty propagation is conducted by Monte Carlo simulation. It is assumed that the coefficient and exponent of Paris law, c and m, are the source of uncertainty. Finally, the probabilistic distribution of the rotor bore fatigue life is obtained.
이동민(Dongmin Lee),김정언(Chungeon Kim),오현석(Hyunseok Oh),황미경(Mikyung Hwang),조기현(Kihyun Cho) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
In this work, the feasibility of reliability evaluation for rotor bore is examined by the first-order reliability method (FORM). Temperature distribution and stress distribution are determined by a heat transfer analysis. The deterministic lifetime of the rotor bore is calculated using the maximum hoop stress and fatigue model. In addition, uncertainty characterization for Pars law parameter is used for crack growth rate test data of Cr-Mo-V. Base on the result of uncertainty characterization, the probabilistic life distribution is obtained by Monte Carlo simulation. Finally, the reliability for the variable crack length is estimated using the FORM.