Research On Multi-Channel Venturi Flow Control System

With the rapid development of my country’s economic and technological strength,the degree of industrial automation is also constantly improving,and the requirements for flow control of various automation control systems in the traditional industrial industry or in the field of military scientific research are increasing.At present,the commonly used gas flow control equipment is the regulating valve,but the gas flow control of the regulating valve has the characteristics that the gas flow control is seriously affected by the downstream pressure,which makes the control accuracy difficult to meet the expected requirements.The adjustable venturi is to add a movable plug cone inside the throat of the traditional venturi to change the throttle area of the throat of the adjustable venturi.When the pressure at the inlet and outlet is stable,the throttle area of the throat is reduced.Changes allow for flow control.Since the throttling area of the traditional venturi throat is fixed,it becomes difficult to control a wide range of flow,but the emergence of adjustable venturi makes it possible,as a component of fluid flow control,has the characteristics of high control accuracy,good control stability,and the control process is not affected by downstream pressure.In recent years,it has been used more and more widely in the field of flow control.In this paper,a set of multi-channel flow control system based on virtual instrument(Lab VIEW)and programmable logic controller(Programmable logic,PLC)is designed with the adjustable venturi tube as the main body of flow control.The system includes a six-channel adjustable Venturi tube body,a PLC-based hardware part of the controller,and control software.The control software of the system is developed by Lab VIEW,which realizes the transmission,display and storage of the motion parameters of the plug cone and the detection of each parameter during the operation of the system.The hardware part includes operation display module,main controller,motion drive module,motion module,data acquisition module and power supply and distribution module.The main controller sends and receives data,the power supply and distribution module supplies power to all parts of the system,and the motion drive module drives the motion module composed of servo motors to control the movement of the plug cone,thereby realizing flow control.The research content of this paper mainly includes the following parts:(1)The main influencing factors of Venturi tube control flow are analyzed,the method of using motor to control the movement of the plug cone is proposed,and the vibration simulation analysis of the plug cone is carried out using ANSYS.The simulation results show that in the process of flow control,the plug The cone does not resonate and does not affect the accuracy of flow control.(2)A hardware matching scheme is designed according to the mechanical parameters of the adjustable venturi body and the index parameters of the movement process of the plug cone,and the theoretical error analysis of the selected hardware is carried out.The results show that the indexes meet the design requirements.(3)According to the high-precision index of plug cone control,it is proposed to use the three-loop PID algorithm for motion control.The simulation model is built and verified by Matlab.The simulation results show that the motion accuracy of the motor can meet the design requirements.At the end of the system The applicability of this algorithm is also verified in the debugging stage of the PID controller,and the practical problem of low control accuracy of the plug cone is solved.(4)Choosing OPC UA as the communication method of the upper and lower computers solves the problem of a large number of bytes sent by parameters,and realizes the one-time transmission of time displacement scattered points to the PLC.Using Lab VIEW to develop the operating software of the upper computer,comparing the characteristics of each mainstream framework,choosing the QMH framework to achieve low coupling of each module and high stability of software operation,complete the design of the operating software,and realize the login of the operator and the automatic operation of the equipment.Check,view and save data and other functions.(5)Test the system,the results show that the control accuracy of the system plug cone meets the design requirements,the whole system has good repeatability,high stability,beautiful man-machine interface,and realizes real-time control of flow.