CFD analysis with fluid-structure interaction of opening high-pressure safety valves

A multi-mesh numerical valve model has been developed to analyze the opening characteristic of highpressure safety valves. Newton’s law and the CFD result for the flow force are used to model the movement of the valve. In incompressible transient flow simulations a large force rise and collapse is caused by a redirection of the bulk flow. This flow-history effect cannot be incorporated in a quasi-steady approach. For real-gases at a set pressure of 40 bar oscillations have been observed during closing of the valve. They are caused by the interaction between the flow in the cavity of the valve disk and the flow towards the valve outlet. At a higher set pressure the flow force continually decreases, which indicates that only a sufficiently fast inlet pressure rise forces the valve to open. With this tool the operation characteristics of safety valves can be assessed to optimize the valve design.