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Wpływ struktury pól prędkości za skokowym zwężeniem rury na wartości współczynników oporów miejscowych

Strzelecka K., Jeżowiecka-Kabsch K.

Systems : journal of transdisciplinary systems science

2008

Vol. 13, spec. iss. 2/2

155--163

Real values of local loss coefficients for flow through pipe sudden contraction (contraction ratio d/D € (035, 0,82) were determined. Variations (in time and vicinity of resistance) and the influence of the Reynolds anmber (Re € (1000, 50000)) on phenomena in the vicinity of sudden contraction were taken into account. Experimental values of ζ coefficients were referred to flow structure in the vicinity of sudden contraction researches. It was pointed out that (for the Reynolds number Re d > Re gr - corresponding to orderly structure of velocity field) obtained ζ coefficient values are lower than those used in engineering calculations.

Effect of elbows and sudden contraction of cross-section on drag reduction effect in surfactant solution flowing in pipe system

Broniarz-Press L., Różański J., Szczecina T.

International Journal of Applied Mechanics and Engineering

2005

Vol. 10, no spec

69-75

The effect of the local frictions on drag reduction in a flow of surfactant solutions in the pipeline system has been studied. The experimental tests for aqueous solutions of hexadecyltrimethylammonium chloride of the concentration of 50, 100 and 150ppm, have been carried out. The flow in straight tubes as well in the pipeline system elements such as elbows and sudden contraction in cross-section has been tested. On the basis of the experimental data it was shown that the presence of the elements giving the local resistances in the pipeline system will bring about the decrease in flow drag reduction effect. The effect can be explained by existing in the systems tested the additional stresses caused by the constructional elements. The additional stresses cause the partial destruction of the shear induced structure SIS (responsible for the flow stabilization) and the decrease of the drag reduction effect.