Journal of the Computational Structural Engineering Institute of Korea (한국전산구조공학회논문집)

Computational Structural Engineering Institute of Korea (한국전산구조공학회)
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Numerical Analysis of Dynamic Response of Floating Offshore Wind Turbine to the Underwater Explosion using the PML Non-reflecting Technique

PML 무반사 기법을 이용한 부유식 해상풍력발전기의 수중폭발에 따른 동응답 수치해석

  • Cho, Jin-Rae (Department of Naval Architecture and Ocean Engineering, Hongik University) ;
  • Jeon, Soo-Hong (School of Mechanical Engineering, Pusan National University) ;
  • Jeong, Weui-Bong (School of Mechanical Engineering, Pusan National University)
  • 조진래 (홍익대학교 조선해양공학과) ;
  • 전수홍 (부산대학교 기계공학부) ;
  • 정의봉 (부산대학교 기계공학부)
  • Received : 2016.09.13
  • Accepted : 2016.12.23
  • Published : 2016.12.30
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Abstract

This paper is concerned with the numerical analysis of dynamic response of floating offshore wind turbine subject to underwater explosion using an effective non-reflecting technique. An infinite sea water domain was truncated into a finite domain, and the non-reflecting technique called the perfectly matched layer(PML) was applied to the boundary of truncated finite domain to absorb the inherent reflection of out-going impact wave at the boundary. The generalized transport equations that govern the inviscid compressible water flow was split into three PML equations by introducing the direction-wise absorption coefficients and state variables. The fluid-structure interaction problem that is composed of the wind turbine and the sea water flow was solved by the iterative coupled Eulerian FVM and Largangian FEM. And, the explosion-induced hydrodynamic pressure was calculated by JWL(Jones-Wilkins-Lee) equation of state. Through the numerical experiment, the hydrodynamic pressure and the structural dynamic response were investigated. It has been confirmed that the case using PML technique provides more reliable numerical results than the case without using PML technique.

본 논문은 효과적인 무반사 기법을 이용한 수중폭발에 따른 부유식 해상풍력발전기의 동응답 수치해석에 관한 내용이다. 수치해석을 위해 무한한 바다 영역을 유한한 영역으로 한정하고 그 경계에서 필연적인 충격파의 반사를 흡수하기 위해 PML(perfectly matched layer)이라 불리는 무반사 기법을 적용하였다. 수중폭발을 수반한 비점성 압축성 유동을 표현하는 일반화된 수송방정식은 방향별 흡수계수와 상태변수를 도입하여 3개의 PML 방정식으로 분리하였다. 풍력발전기와 해수 유동으로 구성된 유체-구조 연계문제는 오일러 기반의 유한체적법과 라그랑지 기반의 유한요소법을 연계하여 반복계산으로 해석하였다. 그리고 수중폭발에 따른 동수압은 JWL 상태방정식으로 계산하였다. 수치실험을 통해 수중폭발에 따른 동수압과 구조 동응답을 분석하였으며, PML 무반사 기법을 적용한 경우가 그렇지 않은 경우에 비해 보다 정확한 해석결과를 제공함을 확인하였다.

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