A problem of thermo-magnetoelasticity for a system of parallel electrical conductors by Cartesian harmonic polynomials and rational functions

2021 ◽  
pp. 108128652110392
Author(s):  
S. M. El Sheshtawy ◽  
H. A. Abdusalam ◽  
M. S. Abou-Dina ◽  
E. K. Rawy
Keyword(s):  
Cross Sections ◽  
Power Plants ◽  
Practical Importance ◽  
Practical Interest ◽  
Transversely Isotropic ◽  
Rational Functions ◽  
Magnetic Vector Potential ◽  
Harmonic Polynomials ◽  
Thermal Boundary Conditions ◽  
Electrical Conductors

A method proposed earlier, relying on the use of harmonic Cartesian polynomial and rational functions, is extended here to find a semi-analytical solution to the uncoupled, two-dimensional problem of thermo-magnetoelasticity for a system of long parallel, non-intersecting, transversely isotropic elastic cylindrical electrical conductors. Results are presented for two conductors of equal circular normal cross-sections carrying currents of equal densities flowing along the same direction, subjected to Robin-type thermal boundary conditions. Quantities of practical interest are represented graphically and discussed. Consideration of a system of electrical conductors is of practical importance in power plants and in various technological instruments, where it is required to assess the interaction between conductors. The obtained formulas for the magnetic vector potential may be of importance for the determination of the coefficients of self- and mutual inductance of long electric conductors, otherwise difficult to calculate by standard methods. Comparing the results with those of a single conductor allows us to assess the interaction between conductors.

Semi-analytical solution by Cartesian harmonic polynomials for a problem of deformation of a long, current-carrying elastic cylindrical conductor

2020 ◽  
Vol 25 (10) ◽  
pp. 1943-1964
Author(s):  
SM El Sheshtawy ◽  
A-SF Obada ◽  
MS Abou-Dina ◽  
AF Ghaleb
Keyword(s):  
Analytical Solution ◽  
Cross Sections ◽  
Power Plants ◽  
Practical Interest ◽  
Transversely Isotropic ◽  
Rational Functions ◽  
Elastic Cylinder ◽  
Transverse Magnetic ◽  
Harmonic Polynomials ◽  
Cross Sectional

Harmonic Cartesian polynomial and rational functions are shown to provide a simple way of obtaining a semi-analytical solution to the uncoupled, two-dimensional problem of thermomagnetoelasticity for a long, transversely isotropic, elastic cylinder carrying an axial, steady electric current. The proposed method involves the solution of a difficult inhomogeneous biharmonic equation for the stress function, and may be invariably used for general geometries of the normal cross-section of the cylinder, for various thermal and mechanical boundary conditions, and also to solve the problem of a long non-conducting cylinder in a transverse magnetic field. At all stages of the solution, there is no need to smoothen the cross-sectional contour in the presence of singular points, as for other methods. Results are provided for the elliptic and rectangular normal cross-sections under the Dirichlet thermal condition and prescribed uniform normal boundary displacement. Quantities of practical interest are represented graphically and discussed. The results may be of interest in determining the deformations occurring in current-carrying metallic parts of structures and machines, and in the central regions of busbars in electric power plants.

Stresses and Deformations of Toroidal Shells of Elliptical Cross Section: With Applications to the Problems of Bending of Curved Tubes and of the Bourdon Gage

1952 ◽  
Vol 19 (1) ◽  
pp. 37-48
Author(s):  
R. A. Clark ◽  
T. I. Gilroy ◽  
E. Reissner
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Practical Interest ◽  
Closed Shell ◽  
Open Shell ◽  
Elliptical Cross Section ◽  
Axially Symmetric ◽  
Elliptical Cross ◽  
Two Parameters ◽  
Toroidal Shells

Abstract This paper is concerned with the application of the theory of thin shells to several problems for toroidal shells with elliptical cross section. These problems are as follows: (a) Closed shell subjected to uniform normal wall pressure. (b) Open shell subjected to end bending moments. (c) Combination of the results for the first and second problems in such a way as to obtain results for the stresses and deformations in Bourdon tubes. In all three problems the distribution of stresses is axially symmetric but only in the first problem are the displacements axially symmetric. The magnitude of stresses and deformations for given loads depends in all three problems on the magnitude of the two parameters bc/ah and b/c where b and c are the semiaxes of the elliptical section, a is the distance of the center of the section from the axis of revolution, and h is the thickness of the wall of the shell. For sufficiently small values of bc/ah trigonometric series solutions are obtained. For sufficiently large values of bc/ah asymptotic solutions are obtained. Numerical results are given for various quantities of practical interest as a function of bc/ah for the values 2, 1, 1/2, 1/4 of the semiaxes ratio b/c. It is suggested that the analysis be extended to still smaller values of b/c and to cross sections other than elliptical.

Recuperators in Gas Turbine Systems

1998 ◽  
Author(s):  
Esa Utriainen ◽  
Bengt Sundén
Keyword(s):  
Research And Development ◽  
Gas Turbine ◽  
Cross Sections ◽  
Heat Exchangers ◽  
Power Plants ◽  
Pressure Ratio ◽  
Compact Heat Exchangers ◽  
Thermodynamic Cycles ◽  
Large Pressure ◽  
Gas Turbine Cycle

The application of recuperators in advanced thermodynamic cycles is growing due to stronger demands of low emissions of pollutants and the necessity of improving the cycle efficiency of power plants to reduce the fuel consumption. This paper covers applications and types of heat exchangers used in gas turbine units. The trends of research and development are brought up and the future need for research and development is discussed. Material aspects are covered to some extent. Attempts to achieve compact heat exchangers for these applications are also discussed. With the increasing pressure ratio in the gas turbine cycle, large pressure differences between the hot and cold sides exist. This has to be accounted for. The applicability of CFD (Computational Fluid Dynamics) is discussed and a CFD–approach is presented for a specific recuperator. This recuperator has narrow wavy ducts with complex cross-sections and the hydraulic diameter is so small that laminar flow prevails. The thermal-hydraulic performance is of major concern.

scholarly journals Interaction in quasibinary systems based on TlSbP2Se6 and compounds of the Tl2Se-Sb2Se3 system

2019 ◽  
Vol 85 (3) ◽  
pp. 20-26
Author(s):  
Viktoria Sabov ◽  
Мaria Potorij ◽  
Iwan Kityk ◽  
Mykhailo Filep ◽  
Marian Sabov
Keyword(s):  
Cross Sections ◽  
Near Infrared ◽  
Practical Interest ◽  
Infrared Range ◽  
Thermally Stable ◽  
Quaternary Compound ◽  
Metal Compounds ◽  
Temperature Method ◽  
The Family ◽  
Near Infrared Range

Complex chalcogenides display semiconductor properties. In particular, heavy metal compounds that are formed in the Tl2Se-Sb2Se3 system are good thermoelectric materials. At the same time TlSbP2Se6 compound belongs to the family of hexaseleno-hypodiphosphates, which representatives have a number of interesting properties (optoelectric, non-linear, etc.) in the near infrared range. The combination of these properties in one material causes some scientific and practical interest, therefore our research was aimed to study the nature of the interaction between TlSbP2Se6 and the thermally stable phases of the Tl2Se-Sb2Se3 system in order to find new promising candidate for applications in electronic devices. The alloys were prepared from corresponding binary, ternary compounds and quaternary TlSbP2Se6 by a direct one-temperature method in evacuated quartz ampoules at temperatures above the melting point of the initial and final products. The initial compounds were synthesized by the reaction of their high purity component elements in stoichiometric proportion. According to the results of the research, it was found that cross-sections based on TlSbP2Se6 and the thermally stable compounds of the Tl2Se-Sb2Se3 section are quasibinary: Sb2Se3–TlSbP2Se6 and TlSbSe2–TlSbP2Se6. Tl9SbSe6 – TlSbP2Se6 and Tl2Se - TlSbP2Se6 systems are not quasibinary, instead quasibinary sections Tl2Se-Tl4P2Se6 and Tl9SbSe6-Tl4P2Se6 which crossing their. The phase equilibrium in Sb2Se3 – TlSbP2Se6 and TlSbSe2 – TlSbP2Se6 systems were studied by common differential thermal analysis (DTA), X-ray powder diffraction (XRD) and microstructure analysis. The eutectic interactions are observed in both systems. The invariant points coordinates are: 77 mol.% TlSbP2Se6, 709 K (system Sb2Se3 – TlSbP2Se6) and 45 mol.% TISbSe2, 680 K (system TlSbSe2 – TlSbP2Se6). Significant boundary solid solutions are formed on the basis of the quaternary compound. Their region extends up to 10 mol% in the system Sb2Se3 – TlSbP2Se6 and to about 18 mol.% in the system TlSbSe2 –TlSbP2Se6 at annealing temperature (573 К). Near the Sb2Se3 and TlSbSe2, the solubility limits do not exceed several mol.%.

A shear center demonstration model using 3D-printing

2021 ◽  
pp. 030641902110574
Author(s):  
Lawrence N Virgin
Keyword(s):  
3D Printing ◽  
Cross Section ◽  
Cross Sections ◽  
Principal Axis ◽  
Practical Importance ◽  
Bending Moment ◽  
Shear Center ◽  
Cross Sectional ◽  
Thin Walls ◽  
Section Profile

Locating the shear, or flexural, center of non-symmetric cross-sectional beams is a key element in the teaching of structural mechanics. That is, establishing the point on the plane of the cross-section where an applied load, generating a bending moment about a principal axis, results in uni-directional deflection, and no twisting. For example, in aerospace structures it is particularly important to assess the propensity of an airfoil section profile to resist bending and torsion under the action of aerodynamic forces. Cross-sections made of thin-walls, whether of open or closed form are of special practical importance and form the basis of the material in this paper. The advent of 3D-printing allows the development of tactile demonstration models based on non-trivial geometry and direct observation.

LOCAL STUDIES OF ICE COVER EFFECTS ON DAM GATES

2021 ◽  
Vol 11 (2) ◽  
pp. 62-66
Author(s):  
Sergey V. EVDOKIMOV ◽  
Alexey A. ROMANOV ◽  
Boris G. IVANOV
Keyword(s):  
Power Plants ◽  
Practical Interest ◽  
Full Scale ◽  
Hydroelectric Power Station ◽  
Hydroelectric Power ◽  
Power Stations ◽  
Operation Rules ◽  
Static Operation ◽  
Technical Operation ◽  
Scale Data

The experience of operation of surface emergency gates in ice-breaking conditions at a number of hydroelectric power plants has shown the insuffi cient eff ectiveness of the methods used to combat freezing of structures. The rules for technical operation of spillway dam gates in winter provide for heating of structures by slots, threshold and skin in conjunction with measures to maintain mines before construction. However, measures to heat gates and build mines are not always suffi ciently justifi ed and justifi ed. In order to obtain full-scale data and scientifi c information for the development of recommendations on operating and accounting modes during design, full-scale studies of stresses and defl ections in the load-bearing elements of the watershed gate of the hydroelectric power station were carried out. This article presents the results of fi eld studies in comparison with calculated values. As a result of the studies, information on the static operation of fl at gates in winter conditions is obtained, which is of theoretical and practical interest. The materials can be used to clarify technical operation rules and to clarify regulatory documents for the design of hydromechanical equipment at hydroelectric power stations.

Recent Investigations in Plastic Torsion

1937 ◽  
Vol 4 (4) ◽  
pp. A163-A169
Author(s):  
C. W. MacGregor ◽  
J. A. Hrones
Keyword(s):  
Shear Stress ◽  
Cross Sections ◽  
Maximum Shear Stress ◽  
Practical Interest ◽  
Modulus Of Rupture ◽  
Double Shear ◽  
Annealed Steel ◽  
Shearing Strain ◽  
Splined Shaft ◽  
Single Set

Abstract Tension, double-shear, and torsion tests on cast iron, S.A.E. 1045 annealed steel, and S.A.E. 1112 annealed steel are described in which the quantitative relations between the so-called modulus of rupture, double shear strength, and actual maximum shear stress in the bar at fracture are given for each material. The shear stress distribution over the cross section of each bar at fracture is also determined. Further, the data obtained from tension and torsion tests on the two steels are plotted on a single set of coordinates, namely the octahedral shearing stress τn and the octahedral shearing strain γn. A reasonable check is obtained between the two curves when the shear strain is less than that corresponding to the tensile strength. Finally, there is described a series of plastic-torsion tests on bars of mild steel with various new cross sections of practical interest, namely, the splined shaft, the circular shaft with two shallow rectangular keyways, double- and four-lipped drills, and I-beams. In these tests, the regions of initial yielding are determined by means of the Fry etching method.

scholarly journals Absolute cross section measurements of 238U(n,f) and 237Np(n,f) in the neutron energy range 1-2.4 MeV

2019 ◽  
Vol 211 ◽  
pp. 03009
Author(s):  
Paula Salvador-Castiñeira ◽  
Franz-Josef Hambsch ◽  
Alf Göök ◽  
Marzio Vidali ◽  
Nigel P. Hawkes ◽  
...  
Keyword(s):  
Cross Section ◽  
Neutron Energy ◽  
Cross Sections ◽  
Energy Region ◽  
Power Plants ◽  
National Physical Laboratory ◽  
Absolute Cross Section ◽  
Neutron Energy Range ◽  
Physical Laboratory ◽  
Low Energies

New standard (n,f) cross sections other than 235U are important to study the relevant cross sections for Generation-IV power plants. A specific need for such standards is for performing new experiments with quasimonoenergetic neutron beams, such as those produced by Van de Graaf accelerators. Neutrons down-scattered to low energies in the experimental environment, so called room-return, become relevant for this type of measurements. Hence, a standard (n,f) cross section with a fission threshold is of great interest, in order to suppress the contribution from room-return background. For this reason we have performed two experiments at the VDG of the National Physical Laboratory to measure absolutely the (n,f) cross sections of 235U, 238U and 237Np in the fast neutron energy region. Our preliminary results are in agreement with the most up-to-date evaluations.

A Variational Method for Fully Developed Laminar Heat Transfer in Ducts

1959 ◽  
Vol 81 (2) ◽  
pp. 157-164 ◽  
Author(s):  
E. M. Sparrow ◽  
R. Siegel
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Variational Method ◽  
Cross Section ◽  
Cross Sections ◽  
Axial Direction ◽  
Circular Sector ◽  
Thermal Boundary Conditions ◽  
Temperature Distributions ◽  
Good Agreement

A variational method is presented for determining fully developed velocity and temperature distributions for laminar flow in noncircular ducts. The heat addition to the fluid is taken to be uniform in the axial direction, but a variety of thermal boundary conditions are considered around the periphery of the duct cross section. Several illustrative examples are given, and comparisons are made which show good agreement with available exact solutions. These examples include ducts of rectangular and circular-sector cross sections.

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