The Structure Design And Model Study Of Double Differential Pressure Dynamic Flowmeter

In the experimental research of hydraulic components and systems,and the state monitoring and fault diagnosing of hydraulic system and equipment,flow is often one of the main parameters that need to be measured and controlled.With the continuous development and application of electro-hydraulic servo valve and electro-hydraulic proportional technology,the requirement of testing technology of electro-hydraulic servo valve and proportional valve is more and more exact.In our country,however,there is not a satisfactory flowmeter for the measurement of dynamic flow with some offset just like dynamic flow controlled by proportional valve.Therefore,this paper used the related principle of hydromechanics,made a detail analysis of realizing the mechanism of dynamic flow measurement based on pressure sensor,deduced the formula of double pressure dynamic flow measuring method,and analysed the influence factors of the measurement.This paper designs a measuring tube for dynamic flow measurement,and uses FLUENT to simulate the flow field,which provides a theoretical basis for the mathematical model of double differential pressure dynamic flowmeter when analysing of the flow state in the pipe.Using two differential pressure to measure can not only overcome the influence of the inertia term and the viscous term in the flow calculation,but also have a simple mathematical model that easy to realize the reverse measurement.No-load hydraulic cylinder + speed sensor type measuring element which is used to measure mainly dynamic flow,as a result of using the large piston area and gap seals,has better dynamic characteristics,typically used for testing the dynamic performance of the servo valve,but because the cylinder piston effective stroke range is limited,it only measure symmetric flow near the servo valve zero area.Base on this,this paper used Symmetrical reciprocating flow as a foundation,then in a transformed electro-hydraulic servo-valve test system,the same typical flow signals controlled by the electro-hydraulic servo-valve were measured with the dynamic flow meter and the dynamic cylinder separately.Basing on the compare and analysis of the data get from experimental,the mathematic model of the instantaneous flow was modified carefully.