Computational Fluid Dynamics Analysis of the Flow Force Exerted on the Disk of a Direct-Operated Pressure Safety Valve in Energy System

The flow force acting on a valve disk plays an important role in the overall performance of pressure safety valves (PSVs). To quantify the disk force, computational fluid dynamics (CFD) methods have been widely implemented. In this paper, the capability of CFD models, and the identification of the most suitable turbulence models' geometry modeling and mesh requirements have been assessed to establish the accuracy of CFD models for disk force prediction. For validation purposes, a PSV disk force measuring rig was designed and constructed to obtain the steady-state flow forces exerted on the valve disk at different valve openings. The CFD model assessment is achieved by comparing the simulation results to experimental measurements; this is achieved in two stages. Stage 1 investigates the use of Reynolds averaged Navier-Stokes (RANS)-based turbulence models where two-dimensional (2D) simulations are performed with five turbulence models. The results indicate that a variety of force results are produced by different turbulence models, among which the shear stress transport (SST) k-omega was found to have the best performance. Stage 2 investigates meshing and the use of symmetry and geometry simplifications; 2D, 1/8 three-dimensional (3D) and 1/2 3D mesh models are examined. The results indicate that the 1/8 3D mesh model is the optimal choice, owing to its higher accuracy and reasonable grid scale. The studies performed in this paper extend the knowledge of compressible flow force prediction, and should facilitate the design or optimization of PSVs.