3D-modeling of swing check valve with connection to dynamic behavior used in system studies

Sammanfattning: This Master’s Thesis is the result of the collaboration between The Technical Faculty of Lund University and TÜV NORD Sweden AB. Focus has been directed towards the nuclear industry where this thesis is one of several other Master’s Theses regarding the dynamic modeling of a swing check valve. It is necessary for the nuclear industry to be able to model flow transients which involve the dynamic behaviour of the swing check valve. The modeling is commonly executed by one-dimensional codes such as RELAP5, DRAKO and DYVRO. This work has applied the swing check valve theory by (Li and Liou, 2003) in order to retrieve results from three-dimensional modeling using computational fluid dynamics (CFD) to derive useful correlations for one-dimensional code implementation. The accuracy of the CFD-model has been investigated by comparing results of interest after changing the modeling set-up in the CFD-software ANSYS FLUENT. The impact of cell density, solver dependence and choice of turbulence model are a couple of interesting preferences which have been investigated in a sensitivity analysis. The simulations are constructed to yield results for useful parameters for the swing check valve theory. Results from CFD-simulations give resembling results compared to the experiments by (Li and Liou, 2003). One particular correlation was found regarding the coupling of the coefficients in the theory of (Li and Liou, 2003) and was implemented in RELAP5. Through this work conclusions has been made that the implementation of a general one-dimensional model based on the theory of (Li and Liou, 2003) will be complex due to coefficient dependence.