DOI QR코드

DOI QR Code

저압터빈 블레이드의 피로손상 해석

Fatigue Damage Analysis of a Low-Pressure Turbine Blade

  • Youn, Hee Chul (Dept. of Mechanical Engineering, Incheon Nat'l Univ.) ;
  • Woo, Chang Ki (Dept. of Mechanical Engineering, Incheon Nat'l Univ.) ;
  • Hwang, Jai Kon (KEPCO Plant Service & Engineering Co., Ltd.)
  • 투고 : 2014.10.08
  • 심사 : 2015.05.02
  • 발행 : 2015.07.01

초록

저압터빈 최종단 블레이드는 발전설비의 대용량화에 따라 대형화 되고 있으며, 터빈을 구성하는 모든 블레이드 중 상대적으로 그 크기가 가장 크다. 그 결과 블레이드는 매우 높은 원심력과 낮은 고유 진동수 특성을 가지며 그에 따른 각종 손상이 발생하게 된다. 최근 국내에서 가동연수 증가와 잦은 기동정지에 따른 저압터빈 최종단 블레이드의 손상이 자주 보고되고 있어, 본 연구에서는 유한요소법을 이용하여 원심력에 의한 응력해석, 응력경화효과에 따른 고유진동수 해석 및 조화응답해석을 수행 하였다. 그 결과 예측된 블레이드의 에어포일 선단부 최대 피로응력의 위치와 실제 균열의 발생위치가 일치함으로써 피로손상에 의한 결과임을 확인하였고, 노치에 의한 등가피로한도가 노치피로한도에 접근하였다.

The sizes of the final blades of a low-pressure (LP) steam turbine have been getting larger for the development of high-capacity power plants. They are also larger than the other blades in the same system. As a result, fatigue damage is caused by a large centrifugal force and a low natural frequency of the blade. Recently, many failure cases have been reported due to repeated turbine startups and their prolonged use. In this study, the causes and mechanism of failure of a LP turbine blade were analyzed by using a finite element method to calculate the centrifugal force, the natural frequency of a stress-stiffening effect, and the harmonic response. It was observed that the expected fatigue damage position matched the real crack position at the airfoil's leading edge, and an equivalence fatigue limit approached a notch fatigue limit.

키워드

참고문헌

  1. Song, G. W., Choi, W. S., Kim, W. J. and Jung, N. G., 2013, "Damage Analysis for Last-Stage Blade of Low- Pressure Turbine," Trans. Korean Soc. Mech. Eng. B, Vol. 37, No. 12, pp. 1153-1157. https://doi.org/10.3795/KSME-B.2013.37.12.1153
  2. Yun, T. j., Kim, D. H., Kim, D. H., Park, L. and Suk, J. I., 2010, "Structural Evaluation and Life Assessment of 5MW Power Generation Gas Turbine Blade," KSME 2010 Spring Annual Meeting, pp. 556-561.
  3. Lucjan, Witek., 2011, " Numerical Stress and Crack Initiation Analysis of the Compressor Blades After Foreign Object Damage Subjected to High-cycle Fatigue," Engineering Failure Analysis 18, pp.2111-2125. https://doi.org/10.1016/j.engfailanal.2011.07.002
  4. Kim, H. J., and Kang, Y. H., 2010, "Crack Evaluation and Subsequent Solution of the Last Stage Blade in a Low-pressure Steam Turbine," Engineering Failure Analysis 17, pp.1397-1403. https://doi.org/10.1016/j.engfailanal.2010.04.005
  5. Wang, W. Z., Xuan, F. Z., Zhu, K. L. and Tu, S.T., 2007, "Failure Analysis of the Final Stage Blade in Steam Turbine," Engineering Failure Analysis 14, pp. 632-641. https://doi.org/10.1016/j.engfailanal.2006.03.004
  6. Yoon, K. B., Ma, Y. W., Kim, Y. I., Cha, S. J. and Kim, Y. J., 2005, "Failure Analysis of Gas Turbine Compressor Blades," KSME 2005 Spring Annual Meeting, pp. 185-190.
  7. Hou, J., Wicks, B. J. and Antoniou, R. A., 2002, "An Investigation of Fatigue Failures of Turbine Blades in Gas Turbine Engine by Mechanical Analysis," Engineering Failure Analysis 9, pp. 201-211. https://doi.org/10.1016/S1350-6307(01)00005-X
  8. Yoo, K. B., Hyun, J. S., Song, G. W. and Kim, J. H., 1999, "Life Evaluation and Nondestructive Diagnosis of Low-Pressure Turbine Blade for Nuclear Power Plant," KSME 1999 Spring Annual Meeting, pp. 913-918.
  9. Kattus, J. R., 1973, Aerospace Structural Metal Handbook, Vol. 2, Code 1403, pp. 1-17.