Numerical and experimental investigation on a conical poppet relief valve with flow force compensation

Numerical and experimental investigations have been carried out in order to study the effect of the poppet geometry on the flow-pressure characteristic of a direct acting pressure relief valve, which is equipped with a flow deflector for flow force compensation. A dynamic 3D-CFD model was built in ANSYS Fluent™, which is capable of simulating the interaction between the fluid flow and the poppet dynamics by means of mesh deformation and of a user-defined function (UDF). This model was applied to predict the flow-pressure characteristics of the valve for different spring preload settings and deflector geometries. The simulated curves were validated using experimental data acquired at FPRL (Fluid Power Research Laboratory) at the Politecnico di Torino, and an excellent agreement was found. The CFD model was then used to predict the effect of geometric parameters of the poppet, such as the cone angle and the position of the deflector. Finally, a 0D model has been developed in order to predict the flow forces; this model requires very few calibration points using 3D-CFD simulations, and can easily be implemented in lumped parameter simulation tools. It was found that this model leads to a satisfactory prediction of the flow-pressure characteristic of the valve.