Simulation Research On Effect Of Edge Geometric Error Of Valve Orifices To Spool Valve Characteristic

Electro-hydraulic servovalves is an important component in electro-hydraulic servo control system, it can change weak signal into the high-power hydraulic pressure signal, major applications in the aerospace, aviation, navigation for direction control, and also use in steel rolling, petrochemical engineering, mining machinery and machine tools. The power stage of servovalves is spool valve, playing the role of hydraulic pressure amplifier. It is composed with valve spool and valve sleeve, it is taking the advantage of the valve spool and sleeve's relative motion to change the area of orifice, the aim is to control the fluid.Edge geometric error of the spool valve orifices has a direct impact to the characteristics of spool valve, and further determines the performance of servovalves, especially effect the discharge characteristic of the null position. The main factors of measuring the quality of valve orifice including the working arris-edge fillet of valve spool's, arris-edge non-verticalness errors of the valve spool, coplanarity errors of valve pocket's quadrate orifice and so on. From the theoretical analysis, numerical simulation and scientific experiments, this thesis researches the relationship between the edge geometric error and valve performance.This thesis firstly gives out the simplified theoretical model of spool valve orifice, based on the orifice formula, it derives the flow formula of the valve orifice while it has different edge geometric errors, and draws the corresponding discharge characteristic curves, it qualitative analysis the effect of every parameter to the valve performances and gets which are the greater impact parameters.And then, it uses the Fluent software which based on the computational fluid dynamics to do the simulation against the parameters which has larger affect to the valve performance. Fluent software uses the finite volume method which develops rapidly in recent years, its efficiency and accuracy are high, and it hasn't been used in the research on the spool valve orifices of micron level. It is the first time of using it in the research of the simulation analysis against discharge characteristics of spool valve in null position, gets the distribution of flow field and discharge characteristics of the ideal and different edge geometric errors spool valve, it gives out the numerical relation of valve orifice's different qualities and valve performance parameters such as discharge gain, nonlinearity degree and consumption flow.Finally, it uses the experiment to certify the results of the simulation is accuracy and reliable. The research provides a reference for the design and qualify tested of servovalves in the future, it is a pioneering research applying value both in theory and project application.