Design Of Measurement Module Of Ultrasonic Gas Meter

Due to the fluidity of the fluid medium,information related to the fluid will be attached to the signal when the ultrasonic wave travels in the fluid medium.The fluid velocity and flow rate can be obtained by ultrasonic signal detection and correlation calculation.In recent years,the country has strongly advocated the use of clean energy such as natural gas to replace the use of polluting energy.The ultrasonic flowmeter has the advantages of high measuring accuracy,contactless measuring,wide range ratio,low pressure loss and internal open-flow devices.In this paper,the causes of experimental errors are analyzed from the direction of fluid velocity,and the fluid flow field in the pipeline is simulated and analyzed by means of computational fluid dynamics.Two comparative experiments were designed: the variation of radial velocity caused by changing the length-diameter ratio of the honeycomb rectifier at the same flow point;Under the same length-to-diameter ratio honeycomb rectifier,the variation of the error caused by the radial partial velocity after changing the fluid flow rate.The experimental results show that the turbulent state of flow field is improved after the honeycomb rectifier is installed.Specifically,with the increase of the length-diameter ratio of the honeycomb rectifier,the radial partial velocity decreases obviously,and the error caused by the radial partial velocity decreases obviously.When the length-diameter ratio exceeds 1.6,the relative error is basically between 0.40 and 0.60.The research object of this paper is ultrasonic flowmeter.To measure the time of countercurrent propagation of ultrasonic signal,several modules were designed,including the ultrasonic excitation signal amplifying circuit,ultrasonic signal amplifying filter circuit,switch switching circuit.Through the experimental test,the excitation signal processed by the circuit can effectively stimulate the ultrasonic transducer,and the weak ultrasonic signal processed by the amplifier filter circuit can also be effectively detected.During the experimental debugging,a graphic display system was designed based on the matlab,which can observe the signal curve,propagation time and temperature of the cis-countercurrent ultrasonic wave at any time.The ultrasonic transducer of model qb200-2was tested.The propagation time under zero flow was compared under z-type direct flow channel and v-type reflected flow channel,and it was found that the time difference of the clockwise and countercurrent propagation was always within 20 ns.In the case of z-type direct flow channel,the number of excitation signals of different square wave is compared,and it is found that increasing the number of excitation signals of square wave can enhance the propagation signal of ultrasonic wave.The propagation time difference is smaller and more stable,and the variation trend of the time difference between the heating process and the cooling process is consistent when the temperature changes.