Pre-stage Flow Field Simulation Of Deflector Servo Valve And Dynamic Characteristics Of Two Stage Servo Valve

Compared with nozzle baffle type and jet tube type servo valves,deflector servo valve has the advantages of strong anti-pollution ability,high reliability,and better dynamic performance.It is widely used in high-end applications in the aviation,aerospace,military and industrial fields.However,there are few studies on the deflection jet flow field and the deflector servo valve,and there is no mature theory for reference.The overall static and dynamic characteristics of the deflector servo valve depend to a large extent on the pre-stage.The pre-stage structure is fine.The pre-stage flow field involves jet,collision,wall attachment and vortex problems.Small changes in the structural parameters will greatly affect the overall performance of the servo valve.Aiming at the influence of the pre-stage structure of the deflector servo valve on its internal flow field and its characteristics,this paper presents a calculation model of the pre-stage flow field based on the change of the split tip height and the nozzle diversion length.The grid is divided,and a complete analysis and calculation of the entire flow process of the oil in the jet plate is performed.The influences of the changes in the splitting tip height and the V-groove nozzle guide length on the pressure characteristics,flow characteristics and jet efficiency of the pre-stage.The paper discusses the causes and hazards of the pre-stage cavitation phenomenon,discusses the two-phase flow control equation followed by the cavitation model,and studies the effects of deflection plate offset and different structural parameters on the prestage cavitation through simulation.Combined with the anti-pollution problem of the servo valve,the causes and harms of erosion and wear are expounded.The erosion and wear rate of solid particles on the perstage is calculated by Euler-Lagrange method,and the influence of different diameters of particles and deflector displacement on erosion and wear on the pre-stage is analyzed according to the simulation results.The mathematical models of the main components of the deflector two-stage force feedback servo valve are established.Under the condition of fully considering the nonlinear flow characteristics of pre-stage,the overall mathematical model of the servo valve is established,and the frequency response of the servo valve is obtained by SIMULINK simulation.Then the influence of different pre-stage structure parameters on the dynamic performance of servo valve is studied by using frequency characteristic as evaluation index.Finally,summarizing the research results of this article,and pointing out the areas where the research can be improved.