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Showing papers in "No source information available in 1987"



Journal Article
TL;DR: In this article, the authors developed a panel method suitable for the analysis of ducted propellers and applied it to the problem of the two-dimensional hydrofoil, the propeller with hub and the axisymmetric duct in uniform flow.
Abstract: : The development of a panel method suitable for the analysis of ducted propellers is presented. The method is first applied to the problem of the two- dimensional hydrofoil, the propeller with hub and the axisymmetric duct in uniform flow. Some comparisons are made with exact solutions and with other panel codes. The difficulties associated with the modeling of ducted propeller flows are discussed. Convergence of the method for a typical ducted propeller is shown. The results include overall forces on the propeller and the duct, circulation distributions, and chordwise pressure distributions on the duct at different positions between blades.

129 citations


Journal Article
TL;DR: In this paper, the tensile properties of concrete reinforced with acrylic, nylon, and aramid fibres, in the form of random distribution or unioxial alignment, were studied by means of three different tests: compact tension, flexural and splitting tensile tests.
Abstract: Fibre reinforcement is one of the effective ways of improving the properties of concrete. However, current studios on fibre -reinforced concrete (FRC) have focused mainly on reinforcements with steel and glass fibres. Thin paper reports on an experimental programme on the properties of various synthetic fibre reinforced cementitious composites and the properties of the reinforcing fibres. Acrylic, polyester, and aramid fibres were tested in uniaxial tension, both in their original state as we!! as after ageing in nerO*nL Samples of these fibres were found to lose varying amounts of strength with time, depending on the ageing temperature. Two different test methods were used to measure the fibre-cement interfacial bond strength. The tensile properties of concrete reinforced with acrylic, nylon, and aramid fibres, in the form of random distribution or unioxial alignment, were studied by means of three different tests: compact tension, flexural, and splitting tensile tests. The properties of concrete, particularly that of apparent ductility, were found to be greatly improved by the inclusion of such fibre reinforcement.

101 citations


Book ChapterDOI
TL;DR: In this paper, an eduction scheme has been developed in an attempt to determine the characteristics of large-scale vortical structures in a turbulent mixing layer, which is applied to a set of experimental data taken in a new, large mixing layer facility designed to minimize boundary and resonance effects.
Abstract: An eduction scheme has been developed in an attempt to determine the characteristics of large-scale vortical structures in a turbulent mixing layer. This analysis scheme has been applied to a set of experimental data taken in a new, large mixing layer facility designed to minimize boundary and resonance effects. The scheme is based on detection of large-scale vorticity concentrations from smoothed vorticity maps, accepting structures of certain size and strength and aligning the realizations through correlation of vorticity. A similar scheme has been developed to apply to the results of a direct numerical simulation of a temporally growing mixing layer. A comparison of the two approaches shows important similarities in details of the coherent structures educed both ways. The numerical simulations indicate that low levels of coherent forcing can dramatically change the evolution of the mixing layer. In the absence of such forcing, the numerical simulations and experiments show a lack of regularity in the transverse position, spacing, amplitude, shape and spanwise coherence of the large-scale vortical structures.

47 citations








Journal Article
TL;DR: In this article, the fiber spinning process of viscoelastic liquid is successfully analyzed by means of a nonlinear integral constitutive equation, finite-element discretization, and Newton iteration.
Abstract: The fiber spinning process of viscoelastic liquid is successfully analyzed by means of a nonlinear integral constitutive equation, finite-element discretization, and Newton iteration. The process is cast and studied both as an initial value problem, which requires the specification of the drawing force, and as a two-point boundary value problem, which requires the specification of the draw ratio. Solutions are obtained up to high elasticity, high draw ratio, and large drawing force. The results agree with the analytic asymptotic solution for Newtonian liquid, with existing numerical solutions in the limiting case of the upper-convected Maxwell liquid, and with available experimental data on spinning of polystyrene melt at 170°C and low-density polyethylene at 150°C.

Journal Article
TL;DR: In this paper, the effect of bank vegetation on the stable channel cross-section of straight gravel rivers is studied theoretically, in which singular perturbation and matched asymptotic expansion techniques are employed to derive the lateral distributions of depth-averaged fluid velocity and the bed shear stress.
Abstract: Effect of bank vegetation on the stable channel cross-section of straight gravel rivers is studied theoretically, in which singular perturbation and matched asymptotic expansion techniques are employed to derive the lateral distributions of depth-averaged fluid velocity and the bed shear stress. A condition of sediment incipient motion is imposed at the junction of the bed and the banks to derive the stable depth, and a formula for resistance to flow is used to obtain the stable width. It is revealed that a thicker vegetation yields a larger depth and a smaller width. Increasing discharge is found to increase the effect of vegetation. The analysis is found to agree reasonably well with available field data.