Research On Digital Vortex Flowmeter Based On TMS320F2812 DSP

Vortex flowmeter has been widely used in many different fields due to its advantages of adaptivity to various media, non-mobile parts, simple structure, stability, low pressure loss and long life etc, which promise that it has a bright future. However, it has poor performance when operated at low flow rate and under pipe vibrations conditions where the Signal-to-Noise ratio is very small, even the signal is submerged by the noise. Many scholars and research institutes do many studies on vortex flowmeter to solve the above-mentioned problems.Inasmuch as the shortage of the analog vortex flowmeter, a pulse output type digital vortex flowmeter has been successfully developed by our research group, which has both DSP and MSP430 microcomputer, a double-core structure. The digital vortex flowmeter in a double-core structure can effectively solve the problem that vortex flowmeter is operated at low flow rate. In the context of the previous efforts, the author made efforts in both the flow measurement at low flow rate and the problem under pipe vibrations conditions. And that a digital vortex flowmeter based on TMS320F2812 DSP is designed successfully.The mainly works of this thesis are as following:1. Improving the predecessor's double-core-structure thought, it is designed that new double-channel type digital vortex flowmeter based on TMS320F2812 DSP. Its principle is DSP detects the vortex signal in two different channels. Spectrum analysis of digital signal is used at low flow rate and frequency counting like analog vortex flowmeters is used in the regular flow range. All of the tasks are accomplished by DSP on its own.2. Impact of pipe vibrations on vortex flowmeters under operating conditions is studied, using the vibrations equipment. Based on the characteristic of the vortex signal, the method of digital notch in frequency domain is used. And the method is realized in the digital vortex flowmeter.The following experiment has proven the feasibility of the present design:1. The flowmeter is calibrated respectively at the water and the gas flow experiment facilities that locate at the Process Detect & Control Laboratory in Tianjin University. And the data shows that the digital flowmeter has the better property at the greater range ratio.2. In the same pipe vibrations conditions, the different digital vortex flowmeters made by YOKOGAWA, ABB and us are tested together. Through comparison, the data shows that the digital flowmeter designed by us has the better performance when operated at low flow rate and under pipe vibrations conditions in the like flowmeters.