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3 International Journal of Applied Mechanics and Engineering

3 2003

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A new description of "diameter effect" in pipe flow of surfactant solutions

100%

Broniarz-Press L. , Różański J.

2003

tom Vol. 8, no spec.

127-133

On the basis of our experimental investigations it was found that proximate causes of an appearance of scale effect should be connected with rheological properties of surfactant solutions and especially with the critical value of shear rate above which the formation the fluid structure of SIS follows. If the value of critical shear rate becomes exceeded in the laminar range of flow, the system achieves the maximal drag reduction in a flow for a given surfactant solution. In case when it takes place in the turbulent range, at a given value of Reynolds number in the pipe of bigger diameter the smaller decrease of friction factor has been observed. We propose for description of "diameter effect" the relation between DR or DDR factors and dimensionless velocity wr.

Characteristics of the flow of the surfactants solutions in the curved pipes

100%

Broniarz-Press L. , Różański J. , Dryjer S. , Woziwodzki S.

2003

tom Vol. 8, no spec.

135-139

In this paper a number of flow experiments in curved tubes with aqueous solutions of the both, cationic and anionic, surface-active agents are presented. It has been shown that taking into account the flow criterion for power-law fluids by Metzner and Reed in the definition of modified Dean number for curved tube is more correct than the use of Reynolds number for clear solvent. The drag reduction in the coils was observed not only in the turbulent flow, but also in the pseudolaminar one. It has been stated that the curvature effect on friction factor for surfactant solutions exists below the critical value of modified Dean number. The value of is higher than this one characteristic for the clear solvent, and linearly increases when geometric modulus decreases.

pH effect on rheological properties of surfactant solutions in hard water

84%

Broniarz-Press L. , Różański J. , Bednarz J.

2003

tom Vol. 8, no spec.

201-206

In the paper the results of experiments on the both, salt and pH effect, on the rheological properties of surfactant solutions (in hard and distilled water) are presented. Three surfactants were used: hexadecyltrimethylammonium bromide (cationic), sodium oleate and potassium oleate (anionic). The special additives were sodium salicylate (NaSal), calcium and magnesium chloride, sodium sulphate, sodium phosphate as well as sodium hydroxide, hydrochloric acid of various concentrations. The studies showed the existing for a given solution the optimal pH value connected with both, the maximum of a viscosity and formation of the shear induced structure SIS. The effect of ions and pH depends on the kind of surfactant/solvent system. It has been shown that the effect of the pH of water on the rheological properties of the solutions studied is more evident for sodium oleate than for HTAB/NaSal.