This master’s thesis presents an experimental study of water flow through a hydraulic siphon in the range of intermediate Reynolds numbers. Particular attention was given to the conversion of mechanical energy into the internal energy of water, as well as to the influence of pipe geometry, elevation difference, pipe cross-sectional area, and pipe length on the flow conditions within the system.
To carry out the research, an experimental setup of a hydraulic siphon was designed, enabling systematic variation of individual conditions and measurement of the time of water flow through the pipe. Based on the measured times, the volumetric flow rate, average flow velocity, and the Reynolds number were determined. The results were compared with theoretical predictions of idealised flow derived using the Bernoulli equation.
The results showed that pipe geometry has a noticeable influence on flow conditions, particularly in pipes with smaller diameters, where additional bends increase the conversion of mechanical energy into the internal energy of water. With increasing elevation difference, both flow velocity and Reynolds number increase; however, the measured velocities were in all cases significantly lower than the theoretical values for ideal flow. The analysis of the influence of pipe cross-section demonstrated that larger diameters enable higher flow velocities and a lower proportion of converted mechanical energy.
The central part of the research consisted of analysing the influence of pipe length on the conversion of mechanical energy into the internal energy of water. It was found that the mechanical energy loss head associated with mechanical losses increases approximately linearly with pipe length, which enabled the use of linear approximations for further analysis of the results. Based on the intercepts of these approximations with the vertical axis, it was possible to estimate the portion of the mechanical energy loss head associated with the water entering the pipe.
The research confirms that mechanical losses in flow through real pipe systems are significant and that the idealised application of the Bernoulli equation, without accounting for the conversion of mechanical energy into internal energy, does not adequately describe actual flow conditions. In addition to its research value, the experimental setup also has educational significance, as it enables a direct comparison between theoretical models and experimental measurements in the study of fluid flow.
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