CFD Prediction of Safety Valve Disc Forces Under Two Phase Flow Conditions

At present there are very few published works on prediction based methods to establish the forces that act on safety valves during two-phase operation. This means that the valve dynamics and resulting opening and closure are uncertain for a wide range of complex flow applications. This paper describes a study whereby a safety valve, primarily developed for the industrial refrigeration sector is investigated for a range of steady state high gas mass fraction inlet conditions, (gas mass quality 1-0.2) and the disc force characteristics measured for valve choked conditions. The highly compressible two phase flow processes are modelled using an Euler–Euler two fluid CFD approach and the results compared with the experiments. Results indicate that CFD approaches can reasonably capture the key processes but deficiencies exist due to the prediction of two phase built up backpressure in the valve. The methods and data trends are discussed to show the effectiveness of current modelling approaches.