Numerical investigation of switching features of a hydraulic seat valve with annular flow geometry

Abstract

This article presents a numerical framework for investigating transient features of hydraulic valves, specifically poppet type designs suited for digital hydraulics. The objective is to determine the validity of the state-of-the-art lumped parameter models (LPM) of fluid dynamical phenomena during switching of such valves. Knowledge about analytically valid models for simple situations are used together with complex Computational Fluid Dynamics simulations, which is not a novel concept, but the procedure at which this is done is. The idea behind the research is to consider a numerical framework with dynamic capabilities as a sufficiently accurate representation of reality. Thereby, strategic simulation cases can be applied to understand the features of the design. The sought dependencies of the valve was revealed by conducting several ‘experiments’ through the simulation framework which allows analysis of practically difficult operating conditions. The results of the numerical framework reveals how and where the state-of-the-art LPM deviate (e.g. that fluid displaced by the plunger itself is not directly proportional to velocity, that fluid inertia is significant and that the fluid-induced force is non-linear with changes in velocity).