| Ultrasonic flow-meter is widely used in all works of life. Especially in current life,the critical shortage of resources such as water, oil and gas and damage of environmentmake the ultrasonic flow-meter to develop towards high precision and high stability. Thisphenomenon not only is beneficial to our country’s “two-oriented society” construction,but also is helpful to achieve the ambitious target about building a beautiful China. Inorder to improve the precision of ultrasonic flow-meter, a lot of research work has beendone such as the basic research of theory on ultrasonic flow-meter, analysis of fluid andadaptability, some algorithm of design and the compensation method of measurementerror. The main content and innovation is as follows:Firstly, the classification and principle of ultrasonic flow-meter is studied, and thenthe characteristic of time difference ultrasonic flow-meter is known. We build the modelof multi-path ultrasonic flow-meter based on the single-path flow-meter. At last, thefactors that influence the precision of ultrasonic flow-meter are analysed. All that can bereferences to the following study.Secondly, we acquire the influence of the distribution of fluid on the precision ofultrasonic flow-meter. Based on the ideal state, the laminar flow, transitive flow andturbulent flow is studied and distribution of velocity is acquired. The distribution of fluidin laminar flow is uniform, while in turbulent flow is relative to Reynolds. The transitiveflow is some kind of especially complicated state between laminar flow and turbulentflow. Then, the flow property of single and double bending pipe is studied at fixedReynolds state. The contoured velocity is developed based on the practical environment,which is beneficial to installation and layout.Furthermore, the influence law on the precision of ultrasonic flow-meter, which isrelative to the degree of roughness, ultrasonic transducers and the number of channels, isobtained from the perspective of adaptability of fluid. At last, we adopt effective measurements to suppress interference and improve the adaptability to fluid, whichfinally makes a great contribution to the improvement of precision.Thirdly, some measures and ways improving the precision are discussed. From adesign point of view of ultrasonic flow-meter, we mainly discuss the drift problem duringthe sampling stage and suppress this problem through effective ways. After distinguish tothe ultrasonic signal, some pretreatment and related filtering methods is developed, whichcan filter the unused signal directing at the characteristic of time difference. At last, thefast-track of fluid velocity is achieved in volatile environments. After all, the precision ofultrasonic flow-meter is greatly improved through different ways.Finally, the method of error compensation is studied. To overcome the nonlinearerrors in environment of actual measurement, the compensation method is discussed fromdifferent aspects. The methods of Newton interpolation and least squares curve fitting areexperimented and the results show that these methods are good to the improvement ofprecision. |
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