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New Design Method for the Formed Suction Intake in Axial-Flow Pumps with a Vertical Axis

Błaszczyk A., Papierski A., Susik M.

Mechanics and Mechanical Engineering

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2016

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Vol. 20, nr 4

553--568

EN

A concept of the formed suction intake design obtained with an algorithm for vertical axial{ ow pumps is presented. The design methodology is a part of works conducted within project no. N N513 460240 supported by the Polish National Science Center. The proposed procedure is used to optimize intakes. The results of steady ow numerical computations in the suction intake as well as applications of the design optimization in the aspect of ful lling two objective functions are discussed. The objective functions given by the authors concern the optimal in ow of the uid into the impeller.

2

A three-scale cracking criterion for drying soils

Hueckel T., Mielniczuk B., El Youssoufi M. S., Hy L. B., Laloui L.

Acta Geophysica

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2014

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Vol. 62, no. 5

1049--1059

EN

Cracking is a most unwanted development in soil structures under-going periodic drying and wetting. Desiccation cracks arise in an apparent absence of external forces. Hence, either an internal, self-equilibrated stress pattern resulting from kinematic incompatibilities, or a stress resulting from reaction forces at the constraints appear as a cracking cause, when reaching tensile strength. At a mesoscale, tubular drying pores are considered in the vicinity of a random imperfection, inducing a stress concentration in the presence of significant pore suction. This approach allows one to use the effective stress analysis, which otherwise, away from the stress concentration, usually yields compressive effective stress and hence a physically incompatible criterion for a tensile crack. Recent experiments on idealized configurations of clusters of grains provide geometrical data suggesting that an imperfection as a result of air entry deep into the granular medium penetrates over 4 to 8 internal radii of a typical pore could yield a tensile effective stress sufficient for crack propagation

3

Transient convective flow of micropolar fluid past a continuously moving vertical porous plate in the presence of radiation

Rahman M. M., Sattar M. A.

International Journal of Applied Mechanics and Engineering

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2007

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Vol. 12, no 2

497-513

EN

An unsteady convective flow and heat transfer of a micropolar fluid past a continuously moving verticaI porous plate with time dependent suction and in the presence of radiation has been analyzed numericaIly. With appropriate transformations the boundary layer equations are transformed into a set of nonlinear ordinary differentiaI equations. The locaI similarity solutions in time of the transformed dimensionless equations for the flow, microrotation and the heat transfer characteristics are evaIuated using the Nachtsheim-Swigert shooting iteration technique. NumericaI results are presented in the form of velocity, microrotation and temperature profiles within the boundary layer for different parameters entering into the analysis. FinaIly, the skin friction coefficient and rate of heat transfer are tabulated for the pertinent parameters.