Study on amendment of orifice equation for small spool displacement and application

The accurate orifice equation was researched. The slide-valve geometric parameter (gap and fillet) was considered, the influence of it on orifice flow was obtained from flow area equivalent and flow average velocity by methods of theoretical analysis and CFD(computational fluid dynamics) numerical simulation. The accurate orifice equation was amended. The accurate valve flow equation considering gap and fillet was acquired by the analysis and calculation of the flow through four valve orifices according to the amended orifice equation. The correlative coefficient of servo valve flow was achieved by linearized analysis for valve flow equation. The curve of flow characteristics against spool displacement considering gap and fillet was achieved. It provided theoretical basis for the design and simulation of Piezoelectric Direct-Drive Valve (PZT DDV) in practical application.