A Theoretical Model for the Velocity Field of the Extrusion of Shaped Sections Taking into Account the Variation of the Axial Component

2010 ◽  
Author(s):  
Parisa Farahmand ◽  
K. Abrinia
Keyword(s):  
Theoretical Model ◽  
Velocity Field ◽  
Axial Component

Wire Stress Calculations in Helical Strands Undergoing Bending

1992 ◽  
Vol 114 (3) ◽  
pp. 212-219 ◽  
Author(s):  
M. Raoof ◽  
Y. P. Huang
Keyword(s):  
Theoretical Model ◽  
Axial Stress ◽  
Operating Conditions ◽  
Radius Of Curvature ◽  
Axial Component ◽  
Practical Applications ◽  
Bending Stresses ◽  
Parametric Studies ◽  
Steel Cables ◽  
The Individual

Steel cables play an important role in many offshore applications. In many cases, an understanding of the magnitude and pattern of bending stresses in the individual component wires of a bent strand is essential for minimizing the risk of their failure under operating conditions. Following previously reported experimental observations, a theoretical model is proposed for obtaining the magnitude of wire bending stresses in a multi-layered and axially preloaded spiral strand fixed at one end and subsequently bent to a constant radius of curvature. The individual wire bending stresses are shown to be composed of two components. The first component is the axial stress generated in the wires due to interwire/interlayer shear interactions between the wires in a bent cable, and the second component is associated with the wires bending about their own axes. Using the theoretical model, which includes the effects of interwire friction, parametric studies on a number of realistic helical strands with widely different cable (and wire) diameters and lay angles subjected to a range of practical mean axial loads, and subsequently bent to a range of radii of curvature with one end of the cable fixed against rotation, have been carried out. It is shown that for most practical applications, the axial component of wire stresses due to friction is much greater than the second component of bending stresses associated with the individual wires bending about their own axes.

Axial Velocity Distribution at the Efflux of a Stationary Unconfined Ship’s Propeller Jet

2010 ◽  
Author(s):  
W. Lam ◽  
D. J. Robinson ◽  
G. A. Hamil ◽  
S. Raghunathan
Keyword(s):  
Velocity Field ◽  
Axial Velocity ◽  
Rotating Flow ◽  
Axial Component ◽  
Large Contribution ◽  
Velocity Magnitude ◽  
Axial Velocity Profile ◽  
Axial Velocity Distribution ◽  
Total Velocity ◽  
Numerical Approaches

This paper is aimed at presenting an up-to-date investigation of the hydrodynamics of the jet (wake) of a stationary, unconfined ship’s propeller. The velocity field of a ship’s propeller jet is of particular interest for the researchers investigating the jet induced damage on a seabed as documented in previous studies. This paper discusses the time-averaged velocity field at the efflux, which is the immediate exit of the downstream propeller jet. The propeller jet is a rotating flow, which has axial, tangential and radial components of velocity. The axial component of velocity is the main contributor to the total velocity magnitude. Researchers are more interested in the axial velocity field within the ship’s propeller jet, due to the large contribution made by the axial velocity to the jet. The axial velocities at the efflux plane were obtained using joint experimental and numerical approaches. The results confirmed the two-peaked ridges axial velocity profile and disagreed with the 0.707Dp contraction suggested by Blaauw & van de Kaa (1978), Verhey (1983) and Robakiewicz (1987) at efflux of a ship’s propeller jet.

scholarly journals Horizontal flow below solar filaments

2018 ◽  
Vol 613 ◽  
pp. A39 ◽  
Author(s):  
P. Ambrož ◽  
W. Pötzi
Keyword(s):  
Magnetic Field ◽  
Velocity Field ◽  
Vector Fields ◽  
Transverse Velocity ◽  
Strong Dependence ◽  
Horizontal Velocity ◽  
Solar Photosphere ◽  
Axial Component ◽  
Filament Axis ◽  
Solar Filaments

Context. Observations of the internal fine structures of solar filaments indicate that the threads of filaments follow magnetic field lines. The magnetic field inside the filament has a strong axial component. Some models of magnetic fields suggest that the field structure in filaments could be caused by the horizontal plasma velocity field near both sides below the filament, where observable shearing effects from the axial component are expected. Aims. The horizontal velocity field in the vicinity of polarity inversion lines is measured in order to determine, if it exhibits a systematic movement that induces shear along the filament axis and convergence perpendicular to the axis. Methods. The horizontal velocity was obtained from the displacement of supergranules, which were derived from Doppler measurements in the solar photosphere. Dopplergrams corrected for rigid rotation and p-mode oscillations were further analyzed by local correlation tracking. Results. Vector fields of the horizontal velocities were measured in 16 areas during 8 time intervals in the years 2000–2002 on both solar hemispheres, each for a few consecutive days. For 64 selected filaments the nearby horizontal velocity vectors were split up into a component along the filament axis and a perpendicular component. Conclusions. Differences between the axial velocities on both sides of the filaments were calculated. In almost all cases the velocity gradient corresponds to the inclination of the threads observed in Hα images. The average transverse velocity does not show any preferred tendency towards a divergence or convergence to the filament axis. Testing the horizontal velocity for the creation of the differential rotation profile in the photosphere reveals a strong dependence of the averaging process on the scale of our velocities.

scholarly journals CO Observations of the Central Bar of M83

1987 ◽  
Vol 115 ◽  
pp. 628-630 ◽  
Author(s):  
T. Handa ◽  
Y. Sofue ◽  
N. Nakai ◽  
M. Fujimoto ◽  
M. Hayashi
Keyword(s):  
Star Formation ◽  
Theoretical Model ◽  
Velocity Field ◽  
Spiral Galaxies ◽  
Raw Material ◽  
Molecular Gas ◽  
Nuclear Region ◽  
Barred Spiral Galaxies ◽  
Co Emission ◽  
Co Observations

CO observations of the nuclear region of the SABc galaxy M83 have been made with the 45-m telescope at NRO. A bar-like elongation of the CO emission along the optical bar and a velocity field which suggests noncircular motions are found. These results are consistent with predictions based on the theoretical model of barred spiral galaxies. The inflow and concentration of molecular gas in the nucleus of M83 may supply raw material which maintains a burst of star formation there.

scholarly journals Computation of Unsteady Blade Forces in Turbomachines by Means of Potential Flow Theory and by Simulating Viscous Wakes

1982 ◽  
Author(s):  
P. Krammer
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Velocity Field ◽  
Flow Field ◽  
Potential Flow ◽  
Flow Theory ◽  
The Other ◽  
Potential Flow Theory ◽  
Flow Fluctuations ◽  
Excitation Mechanisms

This paper describes a new theoretical model which computes two main excitation mechanisms, one based on the potential flow theory and the other explainable by the motion of blades through the wakes of preceding blades. The computation of the potential flow field is based on the assumption of a plane, unsteady, incompressible flow. Fluctuations of circulation caused by an alternating velocity field are taken into account by free vortex paths. Blade surfaces are modeled by a vortex distribution. Viscous wakes are simulated by means of contrarotating vortex rows. Results of the theoretical approach are compared with experimental data measured in axial turbomachines.

Effect of Gravity on the Static and Dynamic Characteristics of a Single Link Component of Flexible Multibody Systems

1993 ◽  
Author(s):  
David W. Smart ◽  
Gloria J. Wiens
Keyword(s):  
Theoretical Model ◽  
Multibody Systems ◽  
Axial Loading ◽  
Flexible Multibody Systems ◽  
Space Structures ◽  
Axial Component ◽  
Large Space ◽  
Gravitational Loading ◽  
Flexible Multibody ◽  
Experimental Findings

Abstract As large space structures and the component links of robotic manipulators become increasingly more flexible, axial loadings are playing an increasingly more important role in the elastic characteristics of the systems. The research presented in this paper provides a relatively simple theoretical model based on the quasi-dynamics of a component link for flexible multibody systems. The theoretical model has shown that the axial component of gravity can play a major role in predicting accurate first and second natural frequencies and the static deflections of component links typical of flexible multibody systems. By definition, the axial loading contribution is a function of rigid body orientation, with the more significant influence occurring in the vertical positions. Furthermore, the degree of this effect is directional, depending on whether the axial loading is compressive or tensile. The results elude to a possible simple, approximation approach for modeling complex multilink systems subject to gravitational loading. In addition, the presented analysis approach has been experimentally validated where the theoretical results have been shown to agree very well with the experimental findings.

Gravitational Effects on Two Link. Flexible Multibody Systems

1995 ◽  
Author(s):  
David W. Smart ◽  
Gloria J. Wiens
Keyword(s):  
Theoretical Model ◽  
Multibody Systems ◽  
Axial Component ◽  
Axial Loads ◽  
Space Applications ◽  
Ground Testing ◽  
Gravitational Loading ◽  
Flexible Multibody ◽  
Theoretical Results ◽  
Elastic Characteristics

Abstract Few flexible multibody studies have been conducted in which gravity is included in the analysis and of these, none include the axial component of the gravitational loading. However, as multibody systems become increasingly more flexible, the axial loads induced by gravity are playing an increasingly more important role in the elastic characteristics of multibody systems, especially in the ground testing of those for space applications. In an effort to minimize the unreliable aspects in ground testing, the research presented here provides a relatively simple theoretical model based on the quasi-dynamics of two link multibody systems with an arbitrary orientation within the gravitational field. The theoretical model has shown gravity does play a significant role in predicting accurate first and second frequencies and the static deflections of such systems. Experimental verification of the theoretical results is presented.

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