CFD as a Design Tool for Fluid Power Components

The paper collects some examples of CFD application to hydraulic components design, aimed at showing how a complex tool can be used both for the internal flow characterisation and the macroscopic analysis of component behaviour.In its first part, the paper deals with the steady-state characterisation of a commercial 4/3 on Zoff distributor, and focuses the attention on CFD strategies used in order to obtain an accurate description of steady-state axial flow-forces, acting on the spool of the component. The solution of simplified models (axis-symmetric) and the development of an extended and novel non-dimensionalization technique are the key to the use of a limited number of distributor configurations and a minimum number of operational conditions to obtain a full characterisation of the component.The second part of the paper is devoted to hydraulic locking analysis, where CFD is applied to tapered 3D geometry in order to validate the results of specific design assumptions and to verify the results obtained by a simplified, though two-dimensional, approach to radial forces estimation in spool valves. As a final example, the last part of the paper is dedicated to particle tracking analysis and collisioni erosion prediction, using a simplified approach based on the hypothesis of uncoupled motion of fluid and particles. In this last case, the CFD computed flow field, is used in arder to allow the solution of the lagrangian equations of motion for solid particles dragged by the fluid according to a given law. The aim of the examples collected is not the solution of the problems dealt with (to this purpose the reader is referred to the bibliography), but rather the identification of areas and methods where the application of a complex and expensive design toollike CFD analysis can reach the breakeven point of a convenient application in the design phase of a hydrauliccomponent