Opis: The influence of the stress state on the deformation response of a rock mass has been experimentally examined on uniaxial, bi-axial and three-axial specimens of marl at short loading and in creep tests for periods of 3 to 180 days. The lateral (horizontal) pressure significantly changes the deformation behaviour of both the initial deformations induced by the stress change and creep deformations. The influence of lateral pressure on the vertical deformation can be well approximated by a linear function. Ključne besede:creep, soft rock, marl, rheological model, lateral stress, laboratory testing Objavljeno v DKUM: 06.06.2018; Ogledov: 695; Prenosov: 54 Celotno besedilo (628,89 KB) Gradivo ima več datotek! Več...

Opis: In the paper a new rheological model for an electrostatic ash and water mixture is proposed. The fundamental equation of the rheological model was used to determine the relationship between the shear stress and the shear rate as well as the equation of a velocity profile for the flow through a straight pipe. Experimental results obtained from a capillary viscometer were used as the basis to determine the parameters for the proposed model by the non-linear regression analysis. With the Quadratic law a numerical analysis of a mixture flow through a capillary pipe with the finite volume method was performed. The derived equations for the velocity profile, shear stress and shear rate were validated through a comparison of numerically obtained and theoretical results. Finally, the compariosn between the Quadratic and the Power law is presented. Ključne besede:fluid mechanics, non-Newtonian fluids, mixture of electrofilter ash and water, flow in pipes, capillary pipes, rheological model, velocity profile, shear stress, finite volume method, numerical analysis, quadratic law, power law, mehanika fluidov Objavljeno v DKUM: 01.06.2012; Ogledov: 2005; Prenosov: 42 Povezava na celotno besedilo

Opis: The non-Newtonian fluid flow in a sharp 90 curved pipe is studied numerically to obtain the pressure loss coefficient prompted by disagreement between the existing empirical correlations and results obtained by computer codes. This disagreement results from presumption of fully developed flow throughout the curvature (correlations) while the actual flow is partially developed for the Newtonian and sharp 90 curved bend non-Newtonian flows, and fully developed for slightly bent 90 curvature non-Newtonian flow. The Quadratic model is employed to accommodate the shear-thickening behavior of an electrostatic ash and water mixture. Numerical results are obtained for different values of Reynolds number. Finally, results for local pressure loss coefficient are compared with values obtained for the Power law rheological model. Ključne besede:shear-thickening fluid, fluid dynamics, rheological model, pipe bend flow, numerical modelling, pressure losses Objavljeno v DKUM: 30.05.2012; Ogledov: 1670; Prenosov: 81 Povezava na celotno besedilo