A Transient Multidimensional CFD Approach to the Analysis of a Control Valve Using Non-Newtonian Fluids

In this paper the flow through a control directional valve is studied by means of a Computational Fluid-Dynamics analysis under transient operating conditions. The mesh motion is resolved on a time basis as a function of the external actuation system. In the analysis, an open source fluid-dynamics code is used and both cavitation and turbulence are accounted for in the modeling. Moreover, the numerical model of the working fluid is modified in order to account also for the non-Newtonian fluids. The effects of the shear rate on the shear stress are accounted for both by using experimental measurements and correlations available in literature, such as the Herschel-Bulkley model. The analysis determines the performance of the control directional valve under different operating conditions when using either Newtonian or non-Newtonian fluids. In particular, the discharge coefficient, the recirculating regions, the flow acceleration angle and the pressure and velocity fields are investigated.