This work is an attempt to study the behaviour of fluid in the mixing vessel with a two-bladed or four-bladed impeller. The working fluid is complex, of a shear-thinning type and the Oswald model is used to describe the fluid viscosity. The study was accomplishedby numerically solving the governing equations of momentum and continuity. These equations were solved for the following range of conditions: 50–1000 for the Reynolds number, 0–0.15 for the baffle length ratio, and the number of impeller blades 2 and 4. The simulations were done for the steady state and laminar regime. The results show that the increase in baffle length (by increasing the ratio baffle length ratio) decreases the fluid velocity in the vessel. Increasing the speed of rotation of the impeller and/or increasing the number of blades improves the mixing process. Also, the length of the baffles does not affect the consumed power.
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W artykule pokazano wpływ wybranych parametrów geometrycznych na rozpływ płynu w przestrzeni międzyrurowej płaszczowo-rurowego wymiennika ciepła. Badania przeprowadzono dla przepływu jednofazowego określając wpływ tych parametrów na opory przepływu.
EN
In this paper the results of influence of geometrical parameters on the flow in shell side of shell and tube heat exchanger was presented. The research for one phase flow was made by determining the influence of the parameters on pressure drop.
Prezentowana praca jest etapem wstępnym do wykonania optymalizacji parametrów geometrycznych mieszadła ślimakowego pra- : cującego w nietypowym układzie geometrycznym, na drodze modelowania matematycznego. Celem głównym pracy było określenie mocy l mieszania mieszadeł ślimakowych o zmiennej średnicy i skoku wstęgi, pracujących z przegrodami o różnej szerokości.
EN
The paper presents a preliminary stage of optimization of geometrical parameters of a screw impeller working in the untypical geometrical arrangement employing mathematical modeling. The main aim of this work was the determination of mixing power for a screw impeller with a variable diameter and pitch, working in a tank with baffles of different width.
The article presents the results of research on the acoustic properties of materials used as sound-absorbing linings and cores in baffles of anti-noise protection. Using an impedance tube the spectral characteristics of the normal incidence sound absorption and sound transmission loss indices of 12 specimens of mineral wool with different density and thickness were determined. From these characteristics, the single-number weighted sound absorption coefficient αw and the sound reduction index Rw were calculated. To calculate the value of the Rw index on the basis of surface mass of the mineral wool specimen, a new formula was proposed. The insertion loss of an acoustic enclosure with one, two and three-layer walls with dimensions of 0.7×0.7 m, containing mineral wool, was determined. The best efficiency was achieved for the enclosure made of walls of layers: mineral wool, placed on the sound source side, steel plate and aluminium plate.
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