CFD Simulation of Steady-State Flow Forces on Spool-Type Hydraulic Valves

A new methodology for determining the steady-state flow force on a hydraulic spool valve has been developed. From a solid model of the valve and valve body, a commercially available CFD package automeshes the volume grid and determines the 3D steady-state flow field and forces on the valve within 36 CPU hrs. This numerical approach enables the quick determination of optimal valve design aimed at improved valve controllability and reduced wear in the hydraulic circuit. To demonstrate this methodology, several simulations were performed aimed at investigating the influence of valve design and valve operating conditions on the steady-state flow force experienced by the valve. The numerical simulations showed that a tapered spool geometry can introduce significant variations in the axial and radial forces (30%). The assumption of an axisymmetric geometry (2D) was also investigated and resulted in flow forces which were approximately a factor of 2 smaller than that predicted by full 3-dimensional simulations. The 3D CFD methodology was validated against experimental data with the predicted flow force agreeing to within 1% of the experimental flow force data.