COMPARATIVE ANALYSIS OF A HYDRAULIC SERVO-VALVE
Keywords:
Servo-valve behaviour, hydraulic CFD, meatus flow description, variable orifice analysis, spool valve discharge coefficient.Abstract
The aim of this work was to obtain the correct hydraulic proprieties of a hydraulic spool servo-valve using computational fluid-dynamics (CFD) techniques and adopting an accurate enough mesh to analyse the flow pattern inside the valve. The zones where thickening of the mesh is necessary have been detected and a method to generate the mesh, based on Reynolds numbers and spool stroke, has successfully been used to minimize computational resources. A comparison with numerical and experimental results (Dong and Ueno, 1999) confirms the accurate description of the behaviour of the valve. The results have been compared with the theoretical behaviour, through a 1D multi-physics model simulation, in order to understand in which conditions the theoretical model is not able to describe the valve properties carefully enough and a more accurate CFD model should be used. As CFD analysis requires high computational resources, a method to improve 1D model accuracy through CFD techniques has been proposed, so that after a preliminary CFD analysis of the valve, it would be possible to analyse a whole hydraulic system with a 1D model.
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