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.
The differential pressure of gas measurement is very often used in industrial measurements. During the gas flow, liquid condensation often occurs. The result is that when measuring a gas flow, the gas-liquid mixture is essentially measured. Errors in the indications of measuring instruments are starting to appear due to a change in the properties of the continuous phase, which is gas. In addition, the appearance of liquid droplets leads to flow disturbances and pressure pulsations. Therefore, new methods and tools for measuring the flow of gas-liquid mixture are being sought. The work involves the use of slotted orifices for measuring gas-liquid mixtures. An analysis of the influence of the slotted orifice geometry on the measurement of the biphasic mixture stream was carried out. Standard orifice and three slotted orifices of various designs. The experiment included measuring the air flow with a small amount of water dispersed in the form of drops.
The paper presents a new design solution for the multi-cylinder compressed air engine, described in the PL 216801 patent. A characteristic feature of the engine is its double-piston operation with pistons working in pairs in opposition and a reciprocating movement in toroidal cylinders. The energy of compressed air was used more effectively in the described engine than in the solutions known so far. Comparing the engine built in accordance with the PL 216801 patent with the parameters of the MP165 and MP3000 engines, lower air consumption in relation to the power generated on the shaft is demonstrated. The described engine uses only one crankshaft and one straight complex shaft, which constitutes an innovative combination of pistons, while maintaining the same engine operation as in the case of two crankshafts operating with phase shift and working chamber shift. Such a solution results in a reduction in the harmful space occurring at the beginning of the power stroke to the value close to “zero”—the necessity to maintain the minimum distance between the pistons working in one cylinder when they are at their closest exists only to for the sake of collision-free operation—which is very desirable for the compressed engine operating with a shift of the working chamber. The mechanical efficiency of the engine has also been improved by guiding the pistons on the complex shaft, and the number of kinematic nodes was decreased by applying only three connecting rods supporting six pistons, which also makes it possible to improve the power and mass relation by approximately 25% in comparison with the currently known engines of similar power.
W pracy podjęto próbę zastosowania wymiaru fraktalnego do identyfikacji powierzchni po obróbce skrawaniem. Celem jest określenie, czy wymiar fraktalny może stanowić miarę diagnostyczną do oceny podobieństwa powierzchni. Praca zawiera opis i wyniki badań eksperymentalnych dla powierzchni po toczeniu, szlifowaniu i nagniataniu. Wyniki pracy mogą mieć zastosowanie w konstruowaniu systemów diagnostycznych. SŁOWA KLUCZOWE: wymiar fraktalny, identyfikacja powierzchni, diagnostyka procesu This paper attempts to use the fractal dimension to identify the surface after the machining process. The objective is to determine whether the fractal dimension can provide a diagnostic measure to evaluate the similarity of the surface. The work contains a description and experimental results for the surface after turning, grinding and burnishing. The results of the work can be used in constructing diagnostic systems.
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