Application of the concept of uncertainty in the field of flow measurement
Journal Title: Комп’ютерне моделювання: аналіз, управління, оптимізація - Year 2018, Vol 1, Issue 1
Abstract
In this paper the problem of fluid flow measurement quality determination is studied. The purpose of any measurement is determination of the measured value, but an obtained value itself is not enough for making a decision based on the results of the measurement, such decision requires also an estimate of measurement quality. The measurement quality can be described with such properties as accuracy, correctness and fidelity. These properties must be determined by the estimates, to which requirements of competence, nonbias and efficiency are applied. One of the main measurement quality properties is accuracy. As its quantitative characteristic, numerical error is commonly used. In particular, the quasi-statistical approach, according to which confidence interval of total error is calculated, is often applied. However, modern theory approaches to estimation of the quality of measurement result in a slightly different way. First of all, it takes to account that the experimenter knows the result and doesn’t know a true value, which means that for the result quality estimation it’s impossible to use an error as an estimate of its deviation from the unknown true value of the measured characteristic. Thus, in this case, it is necessary to use another quantitative characteristic of measurement quality. In this approach, on the one hand, the concept of a true value isn’t used as it is unknown, and on the other hand, the standardized approach to the quantitative estimation of the measurement quality is fulfilled regardless of the origin and way of impact of different factors on the measurement result. In general, uncertainty of the measurement result quantitatively reflects the lack of knowledge about different measurement aspects for specific value. The research of the features of applying uncertainty concept for measurement accuracy estimation in flow survey, for electromagnetic flowmeters in particular, is almost absent. Thus, it is a relevant goal to develop a methodology for application of uncertainty concept in the field of flow measurement. In this paper, an algorithm for estimation of uncertainty in the field of flow measurement is developed and the uncertainty budget is presented. An estimation of the flow measurement uncertainty is done for the electromagnetic flowmeter, embedded into the fluid media dispensing system. Measuring system of the flowmeters consists of flow camera, a couple of coils, which generate a magnetic field in this camera, and a couple of sensor electrodes, built into the camera walls. A moving conductor in this magnetic field is an electrically conductive operating fluid. Estimated values affecting the measurement result are uncorrelated as all of them can be determined with the different instruments and methods and they are not connected with each other. For every input value the standard uncertainty U(Xi) and the uncertainty score Ui(y) are calculated
Authors and Affiliations
Е. В. Титова, В. Я. Тришкин, В. И. Кравец, Д. А. Лосихин
Keywords
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Application of the concept of uncertainty in the field of flow measurement
In this paper the problem of fluid flow measurement quality determination is studied. The purpose of any measurement is determination of the measured value, but an obtained value itself is not enough for making a decisio...