外文翻譯---脈沖輸出型數(shù)字渦街流量計(jì)的研究(已修改)
2025-01-29 23:37 本頁(yè)面
【正文】 附錄AResearch on pulse output model digital vortex flow metersThe vortex flow meter is widely used in different fields due to its flexibility to various media, nonmobile parts, simple structure and long life etc. However, it has poor performance when operating at low flow rate where the SignaltoNoise ratio is very small or even the signal is submerged by the noise. The traditional analog vortex flow meter has benefits of steady signal, high accuracy and good real time in the regular flow range, while it also has a disadvantage of weak signal difficult to detect at low flow rate, which leads to unsatisfying lower limit and a smaller range ratio of 10:1.Based on the previous efforts a pulse output model digital vortex flow meter is developed successfully, which inherits the advantages of the analog one and make up its shortage mentioned above. The digital vortex flow meter with its doublecore structure that means a couple of CPUs made up of DSP and MSP430 identifies the vortex signals from noises by the frequency spectrum analyzing algorithm in DSP at low flow rate where the analog one is not accurate, or even can’t work. Meanwhile it works out by its microcontroller MSP430 the frequency of the vortex signal that is square waves output from preamplifier for the vortex signals in the regular flow range where the SignaltoNoise ratio isn’t too much small and the analog one is accurate and real time.This dissertation consists of theory, hardware/software design and experiment. The main point includes: scheme called doublechannel work model of the pulse output model digital vortex flow meter is designed. The principle is a switch of two different methods to detect the vortex signal. That is using spectrum analysis of digital signal at low flow rate and frequency counting like analog vortex flow meters in the regular flow range. The critical criterion of the switch point is the uncertainty of the frequency. pulse output model digital vortex flow meter is developed successfully. The flow meter is studied respectively at DN25 and DN50 pipelines of the water flow experiment facility and DN50 and DN100 pipelines of the gas flow experiment facility that locate at Process Detect amp。 Control Laboratory in Tianjin University. And the data shows that the digital flow meter has the property of a better lower limit than the analog one and a bigger range ratio of 1:～. Masses of experiments on the digital vortex flow meter have been carried out at the water flow experiment facility and the gas flow experiment facility of Tianjin University respectively. The result shows that the pulse output model digital vortex flow meter has a satisfying lower limit that increases the range ratio effectively, strong ability and good real time and thus it is of great practicability.Th
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