Study On Vortex Signal Digital Processing Method Of Two Channels And Its Application

With versatility in media,simple structure,non-mobile parts,high reliability and stability,oscillatory type flowmeter such as vortex flowmeter and vortex precession flowmeter has been widely used in the field of flowmeter instrumentation.With application of digital method to process vortex signal,the performance of extracting vortex frequency gets improved under low flow situation. How to extract the vortex frequency efficiently under the vibration disturbance condition becomes the main research direction of vortex signal processing.This thesis puts forward the vortex signal digital processing method of two channels based on DSP,aiming at the needs of vibration disturbance and low flow detection.Based on the method,the thesis have developed prototype of vortex flowmeter,which would efficiently eliminate vibration disturbance,improve the performance of low flow detection,and broaden the measuring range.Meanwhile,the thesis presents a design scheme for vortex precession flowmeter based on the two channels technology.In this thesis,the following sections are introduced:1.Vortex signal processing methods,vortex flowmeter and vortex precession flowmeter were introduced.The vortex signal digital processing method of two channels was proposed.Function circuit to realize the method,digital algorithms to extract spectrum from signal,and intelligent algorithm of two channels to eliminate vibration disturbance were designed in the paper.2.This paper successfully designed an intelligent vortex flowmeter converter prototype based on the vortex signal digital processing method of two channels,the functions of which include flowrate measurement,temperature measurement,LCD display,data storage,RS485communication with pc,pulse output,4-20mA current loop output,keys.We developed hardware of the system,embedded software of DSP microprocessor.Through the test on industrial caliberation equipment,we found that the prototype could measure the range from1.84m/s to70.74m/s,and detect fluid flow under vibration disturbance.3.The application of the two channels technology to extract frequency on the vortex precession flowmeter was proposed.Here we introduced the system project design,and set up a test platform.In the experiment on caliberation equipment,we show that the two channels technology can be used on vortex precession flowmeter.In the end, future work is pointed out.