The paper presents a design and application study of a prototype optical
tomograph for the detection and definition of shapes of gas bubbles moving in a
liquid. In the applied method of measurements, the column is exposed to a
homogeneous light beam and next the ray is detected with the use of optical
waveguided detectors. Spatial reconstruction of the bubble shapes is done on the
basis of the signals coming from two perpendicular systems of detectors. The
bubble shape is approximated by an ellipsoid with suitably determined
semi-axes and with the use of genetic algorithms based on the neuron
network. Influence of the structure and dynamics of the measuring path
on errors in representation of gas-bubble shapes and velocities has been
analysed. The paper also contains the results of the tomograph tests.
Vortex flow meters are used to measure the flow of gases and liquids. The flow meters of this type measure the frequency of vortices that arise behind an obstacle set in the path of the flowing fluid. The frequency is a function of the speed of the flowing fluid. This obstacle is called the vortex shedder bar. The advantage of this solution is that the frequency of vortices does not viscose on the rheological properties of the fluid, such as viscosity or density. As a result, the indications of the vortex flowmeter do not depend on the temperature and type of fluid. The work includes numerical and experimental studies of the effect of changing the shape of a vortex generator on the stability of vortex generation in a vortex flowmeter. The article presents a numerical analysis of the influence of selected surfaces of the vortex shedder on the parameters of the vortex flowmeter. In order to determine the influence of the shape of the vortex shedder on the type of generated vortices, simulations were carried out for various flow velocities. Numerical calculations were experimentally verified for a cylinder-shaped vortex shedder. The experimental tests consist in determining the velocity field behind the vortex shedder. For this purpose, a proprietary method of determining local liquid velocities and the visualization of local vortices were used. On the basis of the conducted research, the influence of the shape of the vortex shedder on the width of the von Karman vortex street was determined and the optimal longitudinal distance from the shedder was determined in which it is most useful to measure the frequency of the vortices. This place ensures the stability of the frequency of the generated vortices.
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