A Study of Flow Force on a Spool Valve

Abstract

A spool valve is an indispensable component for controlling fl ow direction as well as fl ow rate in an oil-hydraulic system. Because an axial fl ow force sometimes causes an oscillation of the valve, it is important to predict the axial fl ow force precisely in the design stage. Past representative studies on the axial fl ow force were based on two-dimensional momentum theory and derived two models, which are an approximated equation model and another detailed model. As real spool valves have three-dimensionally complicated confi gurations, it is interesting to study the three-dimensional infl uences on the above equation models. This paper describes high-precision CFD results and the steady/unsteady fl ow force acting on the spool valve through 3D numerical simulations, compared with the above-mentioned equation models.