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Místní tlakové ztráty při proudění vody s přísadou micelárních aditiv
Mík, Václav ; Šesták, J. ; Kořenář, Josef ; Myška, Jiří
We have studied the influence of three cationic surfactants Arquad S50, CTAB and CTAC on three different types of local pressure drops. Experiments were done on a closed hydraulic loop with the range of Reynolds numbers from 1.600 to 23.000. Four different solution concentrations were investigated. Even though all three tested additives show similar drag reduction in the straight tube, there is a substantial difference in effectiveness at local loses.
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Effect of surfactants ageing on drag reduction
Mík, Václav ; Myška, Jiří
Four different surfactants were investigated in a closed hydraulic loop in order to find the influence of age of the solution on drag reducing effectiveness and on decrease of critical shear stress. It shows that ageing of a particular surfactant is dependent on its concentration. Different sensitivity of solutions to flow disturbances indicates an individualism of single surfactants with worm-like micelles.
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Rheology and texture of multiphase emulsion systems
Štern, Petr ; Pokorný, J.
Sensory and texture analyses are important tools to characterise the acceptance of food products by consumers. The aim was to correlate the results of rheological and sensory analysis because they can directly an more easily be applied in production and quality control. As an example were chossen Tartar souces - emulsion of edible oil in an aqueous phase consisting of water, salts, vinegar, modified starch and other flavoring. Functional relations between rheological parameters of tartar souces and sensory characteristics were determined.
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Effect of the heat transfer on the laminar flow in the entrance region of a circular tube
Mík, Václav
An analytical-numerical model of the velocity and temperature field was created, whose parameters are expressed as functions of the thickness of the hydrodynamic and thermal boundary layers. This model converts the set of specific partial differential equations to a set of ordinary differential equations that are always valid in one of three regions into which the entrance region is divided by above mentioned boundary layers.
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