Research On Multi-channel Ultrasonic Gas Flowmeter

At present,multi-channel gas flowmeters have enormous development potential.At the same time,due to advances in technology,multi-channel ultrasonic gas flowmeters have also been greatly improved in measurement accuracy and have exhibited excellent performance in large-diameter measurements,which is widely used in various fields.However,the core technology of high-accuracy ultrasonic gas flowmeters is only in the hands of some famous foreign companies.There is still a lack of high-tech in this area,domestically.Therefore,the purpose of this paper is to do some research on the problems existing in multi-channel ultrasonic gas flowmeters,and solve the key technical problems of multi-channel ultrasonic gas flowmeters.Through the research we can find that there are many problems in ultrasonic metering,especially in the case of complex gas flow field in large diameters,for obtaining a solution of multi-channel ultrasonic gas flowmeter with good stability and high measurement accuracy.Firstly,based on the analysis of fluid theory in the past,the paper is intended to find the breakthrough point according to the distribution law of the flow field.Starting from the basic theory,a mathematical model is established for the two flow states,laminar flow and turbulent flow,and their distribution characteristics are analyzed.At the same time,combining the Reynolds number as a characteristic parameter of the fluid,the corresponding relation between the air velocity and the Reynolds number is obtained under the diameter DN200.Based on the empirical formula of the Prandtl flow velocity distribution in the circular tube,the ultrasonic flowmeter was analyzed in the entire range(0.3~30m/s),and the approximate distribution of the flow velocity in the pipeline was obtained when the flow velocity was different.Secondly,four-channel ultrasonic gas flowmeters were modeled and analyzed,and two models of parallel channel arrangements were established.The first one was based on an evenly spaced arrangement,and four channels divided the pipeline into five equal-width sections.There is also a Gauss-Lengendre channel arrangement method,using the numerical integration method to obtain the weights of the two methods,respectively.According to the empirical formula of velocity distribution,the two methods are simulated separately to obtain their own measurement error.The model reflects the process and results of errormore accurately.Finally,a time-difference multi-channel ultrasonic gas flowmeter was designed to measure the flow velocity.On the basis of the introduction of the main components and components,various functional circuits are designed to achieve the overall circuit design goals.TDC-7200 is used as the core of the circuit for high precision timing chips.Select the MSP430 f55 series as the main control chip.The entire system is relatively simple,the power consumption of the selected single-chip microcomputer is also very low,and it also has good stability.The ultrasonic transducer works at 200 KHz.