Development Of A Differential-pressure Based Vortex Flow Meter For Mass Flowrate Measurement

Vortex flowmeter is designed on the basis of Karman vortex street principle. It iscurrently widely applied to various fields because of the advantages that can not beinstead of. Mass flowrate measurement is a difficult but popular issure in industrialprocess measurement technology. Based on the conventional vortex flowmeter and thefeature of vortex shedding, a new mass flow meter was developed using differentialpressure sensor to detect the vortex signal in the thesis. The dissertation mainlyfocuses on the following contents:(1) Flow measurements especially mass flow rate measurements were brieflysummarized, and vortex flowmeter especially for the mass flow ratemeasurement were detailed discussed. Then, the principle ofdifferential-pressure based vortex flow meter for mass flowrate measurementwas presented and the characteristics and difficulties of this method wereanalyzed.(2) The hardware of the mass flow meter was designed. Based on thecharacteristics of the differential-pressure measurement, signal separatingcircuit, programmable gain amplification and programmable filtering circuitwas designed. The hardware system also includes: micro-processor module,communication module and power system module.(3) The software of the mass flow meter was designed. Based on the analysis ofthe characteristics of the vortex signal, the fast Fourier transform algorithmwas used to deal with the vortex signal. Its accuracy for vortex frequencymeasurement was improved by frequency spectral correction and adaptivefiltering which was designed on MSP430F1611 processor.(4) The result of the demarcating of the system shows that, the mass flow metercould measure multi-parameter of the flow, including the mass flow rate andthe volume flow rate. Experiments were carried out to study on theperformance of the mass flow meter. And the influence of horizontal andvertical assemble patterns on the measurement performance of vortexflowmeter was investigated. The innovation in this thesis is list below: The multi-parameter of the flowwas detected by designing a signal separating circuit; This mass flow meter hadstrong anti-noise ability and wide applicability by adopting programmable gainamplification and adaptive filtering technique; Its accuracy for vortex frequencymeasurement was improved by the fast Fourier transform algorithm to deal withthe vortex signal.