Model Research On Double Differential Pressure Dynamic Flowmeter

Flowmeter is an important measuring instrument in our life.It is widely used in various fields such as industry,agriculture and scientific research,and is closely related to our production and life.Flow measurement generally falls into two categories: steady flow measurement and dynamic flow measurement.Dynamic flow measurement plays an important role in evaluating the dynamic characteristics of servo valves,proportional valves and other control components,flow feedback control and hydraulic parameter testing.Therefore,more accurate and faster dynamic flow measurement has become the premise of modern precision control.Although some new measurement principles and methods have been proposed in recent years,there is no dynamic flowmeter that is economical and practical on the market.Therefore,the measurement of dynamic flow has always been the focus and difficulty of scholars at home and abroad.In this paper,a new differential measurement method for three-point pressure measurement is used to design a dual differential pressure dynamic flowmeter for dynamic measurement.The mathematical model is based on the N-S equation and the Bernoulli equation.The biggest advantage is that the viscous term and the inertia term in the model formula are offset by two differential pressure subtraction methods,which solves the interference of viscosity and inertia on the flow calculation,making the flow formula simple and accurate.At the same time,the dual differential pressure dynamic flowmeter adopts the variable diameter method to obtain the pressure difference,and there is no inertial component in the measuring tube.This design makes the measurement dynamic flow more precise.The symmetry of the flowmeter itself allows for bidirectional measurement of flow.In the FLUENT software,the flow field simulation analysis is carried out on the model.The flow signal is given at the inlet of the flowmeter model.The pressure value is measured on the left,middle and right pressure points of the flowmeter,and then the flow is calculated according to the established mathematical model.The value is compared with the given flow rate of the flow meter inlet to verify the correctness of the mathematical model of the dual differential pressure dynamic flowmeter.In the hydraulic laboratory,an experimental platform compared with the ultrasonic flowmeter was built.The data acquisition card was controlled by the LabVIEW program to collect the differential pressure data at two locations,thereby calculating the flow rate.Using MATLAB software to calculate the weight table for inertia correction of the mathematical model,and then actual measurement of different flow signals,and compared with the test results of the ultrasonic flowmeter,verify the use of weight table to correct the accuracy of the model.The exponential smoothing method and the support vector regression model are used to analyze and predict the corrected flow error,and then the prediction error data for a certain period of time is introduced into the measurement flow calculation program.Ultimately,real-time,accurate measurements of dynamic traffic are achieved.