ACCURACY IMPROVEMENT OF FLOW MEASUREMENT. USING UTTF

Abstract

Flow measurement is an important issue in any process industry or any hydro power plant. For determining the turbine efficiency of hydro-electric power plant, the flow of the water intake should be measured with minimum error. For the accurate control of different parameters like voltage and frequency, the flow should be monitored and controlled accurately. For the measurement of flow, different flow meters are available. Out of them ultrasonic transit time flow meters (UTTFs) are better than others in terms of operational characteristics. The report describes the different factors which are affecting the accuracy of UTTF and suggests different error correction factors for this method. The present work concentrates on the two sources of errors which are affecting the UTTF. They are errors involved in "transit time calculation" and "the errors due to transducer placement". For transit time calculation, two new methods are proposed and the results of the new methods are compared with the already existing methods. From computer simulation,it is proved that the newly proposed methods are much more accurate as compared to the already existing methods. Next focus is on the errors due to the transducer dislocation. This work.simulates the conditions of 1% variation in the transducer position and studied its effects on the accuracy. The multiple-path arrangements of the UTTF meters are studied and it is proved that the accuracy of flow measurement with 8- path method is much better than single path measurement. The simulation environment of this work is carried out using LabVIEW and CFD softwares like FLUENT and GAMBIT. In the measurement and automation tool kit of LabVIEW, the different cases of noise are simulated. In case of CFD software, the GAMBIT is used. for the purpose of designing the channel and FLUENT is used for applying different conditions and simulating the channel. The results of these simulations are applied to MATLAB for further processing like calculation of average velocity and discharge. iv The future scope of this work can be a further improvement of accuracy of flow measurement. Different methods are suggested for further research in this area. The correction. factor in the discharge calculation formula is to be studied for eliminating the transducer location errors. Some other areas of future research are also discussed in this report. v