scholarly journals Influence of the Variable Cross-Section Stator Ventilation Structure on the Temperature of an Induction Motor

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5249
Author(s):  
Junci Cao ◽  
Hua Yan ◽  
Dong Li ◽  
Yu Wang ◽  
Weili Li
Keyword(s):  
Induction Motor ◽  
Cross Section ◽  
Temperature Rise ◽  
High Speed ◽  
Heat Dissipation ◽  
Variable Cross Section ◽  
Variable Cross ◽  
High Speed Train ◽  
Cross Sectional ◽  
Ventilation Hole

The performance of an induction motor, a core component of the high-speed train, is of critical importance to the safety of the train. As a result of limited space in the train and the motor’s high-power density, motor heating poses a grave threat to its service life and operational safety. In this study, a 600-kW high-speed train induction motor model was established and its temperature field calculated by the finite volume method. To optimize the heat dissipation and further reduce the motor temperature rise, a variable cross-section stator ventilation hole was proposed and its influence on the wind velocity and temperature rise comprehensively studied. After comparing the cooling effect of the linear and nonlinear variable cross-section of the ventilation hole, the influence of the cross-sectional diameter and the radial position of the ventilation hole on the temperature rise was explored. Finally, the most favorable scheme for motor heat dissipation was determined.

Longitudinal oscillation of a rod with a variable cross section

2019 ◽  
Vol 14 (2) ◽  
pp. 138-141
Author(s):  
I.M. Utyashev
Keyword(s):  
Cross Section ◽  
Natural Frequencies ◽  
Liouville Problem ◽  
Variable Cross Section ◽  
Variable Cross ◽  
Longitudinal Vibrations ◽  
Cross Sectional ◽  
Independent Functions ◽  
The Cross ◽  
The Right

Variable cross-section rods are used in many parts and mechanisms. For example, conical rods are widely used in percussion mechanisms. The strength of such parts directly depends on the natural frequencies of longitudinal vibrations. The paper presents a method that allows numerically finding the natural frequencies of longitudinal vibrations of an elastic rod with a variable cross section. This method is based on representing the cross-sectional area as an exponential function of a polynomial of degree n. Based on this idea, it was possible to formulate the Sturm-Liouville problem with boundary conditions of the third kind. The linearly independent functions of the general solution have the form of a power series in the variables x and λ, as a result of which the order of the characteristic equation depends on the choice of the number of terms in the series. The presented approach differs from the works of other authors both in the formulation and in the solution method. In the work, a rod with a rigidly fixed left end is considered, fixing on the right end can be either free, or elastic or rigid. The first three natural frequencies for various cross-sectional profiles are given. From the analysis of the numerical results it follows that in a rigidly fixed rod with thinning in the middle part, the first natural frequency is noticeably higher than that of a conical rod. It is shown that with an increase in the rigidity of fixation at the right end, the natural frequencies increase for all cross section profiles. The results of the study can be used to solve inverse problems of restoring the cross-sectional profile from a finite set of natural frequencies.

Analysis of the Variable Cross-Section Duct and Straightening Device Geometry Effects on the Hydrogen Combustion Process

2021 ◽  
pp. 62-71
Author(s):  
O.V. Guskov ◽  
V.S. Zakharov ◽  
Minko
Keyword(s):  
Combustion Chamber ◽  
Cross Section ◽  
High Speed ◽  
Power Plants ◽  
Combustion Process ◽  
Variable Cross Section ◽  
Hydrogen Combustion ◽  
Variable Cross ◽  
Calculation Methods ◽  
Transition Channel

The development and research of high-speed aircrafts and their individual parts is an urgent scientific task. In the scientific literature there is information about the integral characteristics of aircrafts of this type, but there is no detailed consideration of such an important part as the transition channel between the air intake and the combustion chamber. The article considers several flow path configurations. The numerical simulation results of hydrogen combustion in the channels of variable cross section using a detailed kinetic mechanism are presented. Based on the analysis of the data obtained, the models of the transition channel and the combustion chamber showing the best characteristics were selected. The impulse and the fuel combustion efficiency are used as criteria for comparing the flow paths. The difference in the application of two calculation methods is described. The presented results and calculation methods can be used at the stage of computational research of the working processes in advanced power plants.

scholarly journals Theoretical and Experimental Research of The Stability of The Eccentrically Loaded Steel Columns with Variable Cross–Section

2018 ◽  
Vol 7 (3.2) ◽  
pp. 458
Author(s):  
Gennady Trusov ◽  
Vladimir Ruban
Keyword(s):  
Cross Section ◽  
Research Work ◽  
Variable Cross Section ◽  
Suggested Method ◽  
National Standards ◽  
Discrete Models ◽  
Practical Calculation ◽  
Variable Cross ◽  
Cross Sectional ◽  
Steel Columns

The article deals with the problem of determining the ultimate load for the eccentrically loaded steel columns with variable-cross section.The purpose of the research work is to offer an evaluation technique and practical calculation of load-bearing ability of the beam-columns with variable cross-section on the basis of numerical research, which will allow to consider the true form of element deflection curve, the effect of cross-section form, physical nonlinearity of the material, and variety of element boundary conditions. The distinctive characteristic of the suggested method is usage of the discrete models for cross-sectional parts, for the true stress-strain curves of the materials, and for the other input data. The method was tested and the results were compared to known theoretical solutions and national standards. To establish the reliability of the developed method, the experimental study of steel columns with variable cross-section was conducted. The suggested method allows to obtain column curves tables of lowering coefficients for these elements, that can be used in practice of civil engineering, and are convenient with national standards and Eurocode. 

The Changes of Internal Forces and the Reliability of Curved Bridge Taking the Cross-Sectional Design of Axial Symmetrical

2014 ◽  
Vol 587-589 ◽  
pp. 1631-1636
Author(s):  
Zheng Jiu Zhao ◽  
Jing Hong Gao
Keyword(s):  
Cross Section ◽  
Variable Cross Section ◽  
Radius Of Curvature ◽  
Variable Cross ◽  
Cross Sectional ◽  
Box Girder ◽  
Curved Bridge ◽  
The Cross ◽  
Cross Sectional Design ◽  
Bridge Models

Taking a bridge of 160m long variable cross-section prestressed continuous curved box-girder as the research object and analyzing the cross-sectional design of axis with axial symmetrical or axial non-symmetrical to research the structure forces change of the upper part of bridge in different curvature. In order to test and verify the variable cross-section of prestressed continuous curved box-girder bridge is safe and reliable via cross-sectional design with axial symmetrical instead of axial non-symtrical within a radius of curvature of the interval. Creating the straight bridge and curved bridge models with different radius of curvature in same span by Midas/Civil to compare their structure forces.

Solar Concentrator Structural Optimization: A Variable Beam Cross Section Design

2017 ◽  
Author(s):  
Moucun Yang ◽  
Yuezhao Zhu ◽  
Wei Fu ◽  
Garth Pearce ◽  
Robert A. Taylor
Keyword(s):  
Structural Optimization ◽  
Cross Section ◽  
Cost Savings ◽  
Variable Cross Section ◽  
Variable Cross ◽  
Maximum Displacement ◽  
Cross Sectional ◽  
Optical Efficiency ◽  
Box Structure ◽  
Section Design

The design and construction of solar concentrators heavily affects their cost, heat utilization and optical efficiency. Current trough concentrators support the reflector with an equivalent uniform beam configured from a metal grid sub-structure. Under gravity and wind loads, the support-structure stress distribution varies as a function of position of the structure and the tracking angle. In the conventional design, there is ample surplus stiffness and strength designed into some beams of the structure, which increases the overall weight and cost of the structure. This paper describes an approach towards structural optimization of trough concentrators (with the Eurotrough design taken as an example, that means that the safety factors and structure is similar with Eurotrough design) using a variable cross section beam. The main improvement of this approach comes from keeping the beams rigid and strong near the two ends (at the torque box structure) while allowing the middle of the structure to be relatively weak. Reducing the cross-sectional area of the central beams not only reduces amount of material needed for the structure but also reduces the deflection of the reflector. The simulated results show that the concentrator’s structural weight (including the torque box, endplates and cantilever arms) and the maximum displacement of the reflector are reduced about 15.3% (about 151.2kg per 12-metre long element) and 15.5%, respectively. This represents a meaningful capital and installation cost savings while at the same time improving the optical efficiency.

scholarly journals A well-balanced solver for the Saint Venant equations with variable cross-section

2015 ◽  
Vol 23 (2) ◽  
Author(s):  
Raul Borsche
Keyword(s):  
Numerical Method ◽  
Cross Section ◽  
Variable Cross Section ◽  
Test Cases ◽  
Variable Cross ◽  
Bottom Slope ◽  
Cross Sectional ◽  
Analytical Properties ◽  
Saint Venant Equations ◽  
Numerical Solver

AbstractIn this paper we construct a numerical solver for the Saint Venant equations. Special attention is given to the balancing of the source terms, including the bottom slope and variable cross-sectional profiles. Therefore a special discretization of the pressure law is used, in order to transfer analytical properties to the numerical method. Based on this approximation awell-balanced solver is developed, assuring the C-property and depth positivity. The performance of this method is studied in several test cases focusing on accurate capturing of steady states.

Transmission Loss of Variable Cross Section Apertures

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
J. Li ◽  
L. Zhou ◽  
X. Hua ◽  
D. W. Herrin
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Sound Propagation ◽  
Transmission Loss ◽  
Element Model ◽  
Variable Cross Section ◽  
Variable Cross ◽  
Cross Sectional ◽  
Radiation Impedance ◽  
The Cross

Openings in enclosures or walls are frequently the dominant path for sound propagation. In the current work, a transfer matrix method is used to predict the transmission loss of apertures assuming that the cross-sectional dimensions are small compared with an acoustic wavelength. Results are compared with good agreement to an acoustic finite element approach in which the loading on the source side of the finite element model (FEM) is a diffuse acoustic field applied by determining the cross-spectral force matrix of the excitation. The radiation impedance for both the source and termination is determined using a wavelet algorithm. Both approaches can be applied to leaks of any shape and special consideration is given to apertures with varying cross section. Specifically, cones and abrupt area changes are considered, and it is shown that the transmission loss can be increased by greater than 10 dB at many frequencies.

Analysis of Singly Symmetric Oval Rings with Variable Cross Section

1970 ◽  
Vol 14 (03) ◽  
pp. 143-152
Author(s):  
J. E. Flaherty ◽  
W. P. Vafakos
Keyword(s):  
Cross Section ◽  
Variable Cross Section ◽  
Experimental Results ◽  
Variable Cross ◽  
Cross Sectional ◽  
Shear Loads ◽  
Good Agreement

An analysis of singly symmetric oval rings with variable cross-sectional properties, subjected to arbitrary radial and shear loads, is presented. The flange stresses in nonuniform reinforcing rings of ring-stiffened oval cylinders are obtained by assuming that such cylinders behave as composite rings. The stresses are shown to be in good agreement with available theoretical and experimental results.

Partially Vaned Diffuser With Variable Cross-Section for Centrifugal Fans

2017 ◽  
Author(s):  
Tore Fischer ◽  
Sebastian Burgmann ◽  
Manuel Rudersdorf ◽  
Joerg R. Seume
Keyword(s):  
Cross Section ◽  
Pressure Ratio ◽  
Variable Cross Section ◽  
Cross Sectional Area ◽  
Variable Cross ◽  
Centrifugal Fan ◽  
Sectional Area ◽  
Cross Sectional ◽  
Vaned Diffuser ◽  
Part Load

The present research focuses on the efficiency improvement at part-load of a centrifugal fan for a 30 kW fuel cell combined heat and power (CHP) unit. For this purpose, the fan stage is equipped with a partially vaned diffuser with a variable cross-sectional area using a moving backplate. The design and the performance of the partially vaned diffuser with a variable cross-sectional area are described in the first part of this paper. The performance results are compared to measurements of the same centrifugal fan with a vaneless diffuser carried out for the previous investigation. For the second part, the influence of the variable cross-sectional area on the diffuser flow field is investigated using optical PIV (Particle Image Velocimetry) measurements and CFD (Computational Fluid Dynamics) simulations. The combination of a variable cross-section, partially vaned diffuser was able to achieve a 10 percent increase in pressure ratio, a 5 percentage points increase in part-load efficiency while maintaining the whole operating range of the vaneless, constant cross section reference design.

scholarly journals Re-Reflection Effect On Shock Waves in Two-Phase Flows through a Tube of Variable Cross-Section

2018 ◽  
Vol 3 (12) ◽  
pp. 67-73
Author(s):  
Kanti Pandey
Keyword(s):  
Cross Section ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Variable Cross Section ◽  
Variable Cross ◽  
Reflection Effect ◽  
Two Phase Flows ◽  
Particle Volume ◽  
Two Phase ◽  
Cross Sectional

In present paper Re-reflection  effect on  shock –waves in two-phase flows through a tube of variable cross-section is considered when particle  volume fraction appeared as an additional variable .It is concluded that re-reflected effects reduce the cross sectional  area .For two-phase flows when equilibrium is eventually established , presence of particle volume fraction , further reduce  the cross – sectional area. One dimensional area relation for a non – uniform , steady flow ahead of a shock   is obtained and concluded that  all the results are valid for the case   when  direction of the shock motion and the gas flow ahead of the  shock is same  .  In preparation of graphs Mathematica 7 is used .

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