The present study provides recommendations for choosing the appropriate dynamic mesh techniques of computational fluid dynamics(CFD) to describe the dynamic characteristics of a check valve in nuclear power plants. Four different methods were proposed to simulate the check valve closure using the dynamic mesh techniques of CFD, and strategies were also proposed to describe the full closure of the valve. The closing behavior of the 10-inch check valve installed in the nuclear power plant was measured. The actual closing of the check valve was analyzed by applying the four methodologies proposed in this study, and the analysis results were compared with the measurement. In addition, the analysis models were generated to simulate the check valve closure with a constant angular velocity for comparison between each method, and the pressure build-up in response to the valve’s closing behavior were evaluated. The results showed that the check valve’s dynamic behavior during the valve closure could be well described by the proposed methods, and there was no significant difference beween each method in terms of fluid velocity and pressure around the disc. The velocity profiles at the outlet of each method were similar until the valve was almost closed. However, even though the proposed methods described the check valve’s closing behavior well, the predictions of the inflow velocity for the immersed boundary method when the valve was fully closed were different from the other methods.
본 연구에서는 원자력발전소 역지밸브의 동적특성 분석을 위한 해석 방법론을 제안하였다. 전산유체역학(Computational Fluid Dynamics; CFD)의 동적격자 방법론을 활용하여 역지밸브의 닫힘을 모사하기 위한 4가지 방법론을 제안하였으며, 밸브의 완전 닫힘을 모사하기 위한 전략을 함께 제안하였다. 원자력발전소에 설치된 10인치 역지밸브의 닫힘 거동을 측정하였으며, 본 연구에서 제안하는 4가지 방법론을 적용하여 역지밸브의 실제 닫힘에 대한 해석 결과와 비교하였다. 또한 각 방법론 간의 비교를 위하여 일정한 각속도로 닫히도록 해석모델을 구성하였고, 닫힘 시의 밸브 거동과 유체의 압력상승 거동을 분석하였다. 해석 결과, 각 방법론은 모두 역지밸브의 실제 닫힘 거동을 유사하게 모사하였고, 특히, 닫힘이 진행되는 동안에는 디스크 주변 영역의 유체 속도와 압력 측면에서 방법론 간에 유의미한 차이를 보이지 않았다. 그러나 일정한 각속도로 닫히는 경우의 해석 결과는 완전 닫힘이 이루어지는 순간의 디스크 주변 영역의 유체 속도와 닫힘 방향 유체의 압력상승을 예측함에 있어 가상경계법(Immersed Boundary Method)의 결과가 다른 3가지 방법론과 차이를 보였다.