| Jet deflector servo valve has the properties of strong contamination resistant,high reliability and good structure which have widely used in aviation and aerospace and has the tendency of replacing other types servo valve all round.Due to the jet deflector servo valve within the fluid flow is complex and flow speed is high,so that the electro-hydraulic servo valve is easy to be eroded by particles in the jet flow,resulting in performance degradation or even failure of servo valve.Therefore,the study on the erosion of the servo valve and its influence on the life prediction and failure analysis of the servo valve is of great significance.In this paper the methods of theoretical analysis and numerical calculation are combined.the influence of the particles in the oil on the pre-stage is studied,and the influence of erosion wear on the servo valve is analyzed.In chapter 1,the research background and means of the jet deflection servo valve erosion are described,researching status and development of domestic and abroad of jet deflector servo valve and two electro-hydraulic servo valve are summarized,especially application and development of erosion in the field of hydraulic.In chapter 2,the basic structure and working principle of electro-hydraulic servo valve is introduced.The Euler Lagrange method in two-phase of solid-liquid flow are summarized which is applied in the simulation of erosion in jet deflector servo valve,the force suffered of particle in the flow and motion trajectory of particles are described;Combining computational fluid dynamics and erosion wear of pre-stage of jet deflection servo valve caused by particles in high speed oil are simulated.Predicting the location of erosion,trajectory calculation and calculation of particle erosion rate are also calculated;In chapter 3,according to the structure parameters of jet deflector servo valve is different such as jet nozzle width,the angle of V shaped groove,deflection plate thickness on the pre-amplifier.Differential pressure of two receiving hole and erosion wear rate were analyzed;After erosion the structure of the servo valve pre-stage is established based on the numerical calculation result.The effect of erosion on the pre-stage flow field and receiving hole pressure difference and zero pressure gain are researched.In chapter 4,the mathematical modeling of jet deflector servo valve of the main components and the whole mathematical model of the servo valve are established.The curves of erosion wear on before and after erosion for the pre-amplifier of differential pressure in two receiving hole are fitted.The relationship between the two receiving hole differential pressure and deflection plate displacement are obtained;The AMEsim model of jet deflection servo valve are established.combining the fitting curve and the AMEsim model,before and after the erosion of jet deflection servo valve spool displacement,load flow changes are studied.In the end,the main research work and achievements of this paper are summarized,and the contents of the research and the further research are prospected. |
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