Transient flow forces estimation on the pilot stage of a hydraulic valve

The effect of flow forces on the spool equilibrium of hydraulic components is well known, and a number of methods have been developed in order to estimate their effect. They span from analytical expression, to experimental evaluation, to CFD analysis. This last approach is usually considered too demanding to the purpose of hydraulic component design, however a careful approach to the problem statement can lead to the collection of a complete set of data, starting from a limited number of numerical runs. A further extension to transient flow is made possible by the acceptance of further approximations on the effect of fluid compressibility, leading to a computational technique able to extend the amount of information extracted from a single model.