Design Of Two-phase Flow Cross-correlation Measurement System Based On Virtual Instrument

The Parameter measuring of two-phase flow is a problem that not have been solution longtime,and obtain its parameters in real time and accurate has important significance forimproving productivity and avoiding accidents.The measurement of two-phase flow parameter is of great significance for computation,control and energy conservation. However, measuring two-phase flow parameters has not beensatisfactorily resolved, and it has become a major problem hindering industrial production andthe productivity improvements.In the design process, generally, the two-phase cross-correlation measurement systemusing two identical sensors for signal acquisition. First, the fluid noise signal changesconverted into the electrical signal by the sensor, and then through the signalconditioning circuit to amplify and filter。The transit time between upstream and downstreamsignals is calculated using the correlation of these two signals. Finally calculate the two-phaseflow and other parameters.This design combined computer simulation to experiment research, and established across-correlation measurement system based on the virtual instrument PXI platform throughthe research of the composition, working principle and mathematical models of the cross-correlation measurement system for two-phase flow. Based on the cross-correlation functionmodule and auto-correlation function module provided by the LabVIEW signal computingsection, two-phase flow measurement systems were designed respectively using cross-correlation function, polar cross-correlation function and differential autocorrelation function.The calculation results were compared through simulations to verify the accuracy of the systems.The cross-correlation velocity measurement experiment system uses a magnetic pump asthe power source of the fluid, and a pair of JYB-G type pressure transmitters mounted on avertical pipe as sensors. The diameter of the fluid conduit is40mm, and the distance betweenthe two sensors is80mm. The system acquires data with the PXI-6221data acquisition card,and calculates and displays the data with the correlation functions to the software of LabVIEW.When the system works, random signals measured by the upstream and downstream sensors are sent to the incoming the data acquisition card through the SCB-68junction box, andthen transferred into the LabVIEW calculating system by the DAQ Assistant module. TheLabVIEW system parses out the transit time through cross-correlation calculation, and the two-phase flow rate can be derived by dividing the sensor distance with the transit time.This article focuses on the two-phase flow cross-correlation measurement systemimplementation process based on virtual instrument technology and correlation principle, andthen shows the LabVIEW computer program language and measurement results。Finallyanalyzed the error of measurement results.