scholarly journals COMPARATIVE ANALYSIS OF GAS VELOCITY INFLUENCE ON THE TEMPERATURE FIELD AND HYDRODYNAMIC LOSSES IN THE EXCHANGER SECTION OF THE COMPACT EXHAUST BOILER

2017 ◽  
pp. 77-85
Author(s):  
Denis Igorevich Bevza ◽  
Sergey Nikolaevich Valiulin ◽  
Oleg Petrovich Shuraev
Keyword(s):  
Boundary Condition ◽  
Temperature Field ◽  
Cross Section ◽  
Gas Dynamics ◽  
Geometrical Model ◽  
Dynamic Resistance ◽  
Gas Velocity ◽  
Gas Dynamic ◽  
Temperature Mode ◽  
Original Calculation

The analysis of the numerical modeling results of gas dynamics in the ducts of the compact exhaust boiler is continued. Currently, there have been done three calculations for the same geometrical model; these calculations have different input speed values, as well as different methods of setting speed. It’s confirmed that in case of continuation of the original calculation with changed boundary condition (speed) in the inlet cross section the results coincide with results of calculation where originally set speed was the same. Thus, it becomes possible to perform several variants of calculations with the same geometry, but with different speed in one session (with minimum correction of initial data). So, the time of setting new temperature mode and the value of gas-dynamic resistance is reduced. Therefore, the time for preparing and carrying out the numerical experiment can be reduced. The influence of input speed on temperature field and hydrodynamic losses in exhaust boiler have been analyzed.

scholarly journals Three-Dimensional Electro-Thermal Analysis of a New Type Current Transformer Design for Power Distribution Networks

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1792
Author(s):  
Bingbing Dong ◽  
Yu Gu ◽  
Changsheng Gao ◽  
Zhu Zhang ◽  
Tao Wen ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Temperature Field ◽  
Temperature Gradient ◽  
Field Distribution ◽  
Distribution Network ◽  
Current Transformer ◽  
Internal Temperature ◽  
Temperature Field Distribution ◽  
Type Design ◽  
New Type

In recent years, the new type design of current transformer with bushing structure has been widely used in the distribution network system due to its advantages of miniaturization, high mechanical strength, maintenance-free, safety and environmental protection. The internal temperature field distribution is an important characteristic parameter to characterize the thermal insulation and aging performance of the transformer, and the internal temperature field distribution is mainly derived from the joule heat generated by the primary side guide rod after flowing through the current. Since the electric environment is a transient field and the thermal environment changes slowly with time as a steady field under the actual conditions, it is more complex and necessary to study the electrothermal coupling field of current transformer (CT). In this paper, a 3D simulation model of a new type design of current transformer for distribution network based on electric-thermal coupling is established by using finite element method (FEM) software. Considering that the actual thermal conduction process of CT is mainly by conduction, convection and radiation, three different kinds of boundary conditions such as solid heat transfer boundary condition, heat convection boundary condition and surface radiation boundary condition are applied to the CT. Through the model created above, the temperature rise process and the distribution characteristics of temperature gradient of the inner conductor under different current, different ambient temperatures and different core diameters conditions are studied. Meanwhile, the hottest temperature and the maximum temperature gradient difference are calculated. According to this, the position of weak insulation of the transformer is determined. The research results can provide a reference for the factory production of new type design of current transformer.

An analytical solution of a two-dimensional temperature field in a hollow cylinder under a time periodic boundary condition using Fourier series

2009 ◽  
Vol 223 (8) ◽  
pp. 1889-1901 ◽  
Author(s):  
G Atefi ◽  
M A Abdous ◽  
A Ganjehkaviri ◽  
N Moalemi
Keyword(s):  
Boundary Condition ◽  
Temperature Field ◽  
Fourier Series ◽  
Temperature Distribution ◽  
Analytical Solution ◽  
Hollow Cylinder ◽  
Periodic Boundary Condition ◽  
Periodic Boundary ◽  
Separation Of Variables ◽  
Two Dimensional

The objective of this article is to derive an analytical solution for a two-dimensional temperature field in a hollow cylinder, which is subjected to a periodic boundary condition at the outer surface, while the inner surface is insulated. The material is assumed to be homogeneous and isotropic with time-independent thermal properties. Because of the time-dependent term in the boundary condition, Duhamel's theorem is used to solve the problem for a periodic boundary condition. The periodic boundary condition is decomposed using the Fourier series. This condition is simulated with harmonic oscillation; however, there are some differences with the real situation. To solve this problem, first of all the boundary condition is assumed to be steady. By applying the method of separation of variables, the temperature distribution in a hollow cylinder can be obtained. Then, the boundary condition is assumed to be transient. In both these cases, the solutions are separately calculated. By using Duhamel's theorem, the temperature distribution field in a hollow cylinder is obtained. The final result is plotted with respect to the Biot and Fourier numbers. There is good agreement between the results of the proposed method and those reported by others for this geometry under a simple harmonic boundary condition.

scholarly journals Isospectrals of non-uniform Rayleigh beams with respect to their uniform counterparts

2018 ◽  
Vol 5 (2) ◽  
pp. 171717 ◽  
Author(s):  
Srivatsa Bhat K ◽  
Ranjan Ganguli
Keyword(s):  
Boundary Condition ◽  
Cross Section ◽  
Natural Frequencies ◽  
Rectangular Cross Section ◽  
Beam Equation ◽  
The Finite Element Method ◽  
Rayleigh Beam ◽  
Uniform Beam ◽  
Governing Differential Equation ◽  
The Given

In this paper, we look for non-uniform Rayleigh beams isospectral to a given uniform Rayleigh beam. Isospectral systems are those that have the same spectral properties, i.e. the same free vibration natural frequencies for a given boundary condition. A transformation is proposed that converts the fourth-order governing differential equation of non-uniform Rayleigh beam into a uniform Rayleigh beam. If the coefficients of the transformed equation match with those of the uniform beam equation, then the non-uniform beam is isospectral to the given uniform beam. The boundary-condition configuration should be preserved under this transformation. We present the constraints under which the boundary configurations will remain unchanged. Frequency equivalence of the non-uniform beams and the uniform beam is confirmed by the finite-element method. For the considered cases, examples of beams having a rectangular cross section are presented to show the application of our analysis.

Rotational Temperature Measurement in Multicomponent Gases Using Raman Scattering Spectroscopy

1976 ◽  
Vol 30 (2) ◽  
pp. 179-183 ◽  
Author(s):  
R. S. Hickman ◽  
A. E. Kassem ◽  
L. H. Liang
Keyword(s):  
Temperature Field ◽  
Raman Scattering ◽  
Temperature Measurement ◽  
Cross Section ◽  
Room Temperature ◽  
Rotational Temperature ◽  
Raman Scattering Spectroscopy ◽  
Scattering Experiment ◽  
Cross Section Area ◽  
Section Area

The rotational temperature at pressures near 1 atm and at room temperature has been successfully measured using spectra obtained in an intracavity Raman scattering experiment. The accuracy of the method is sufficient to allow local temperature measurement of multicomponent gases with no disturbance in the temperature field. The advantage of the method lies in the fact that it does not require knowledge of the relative scattering cross-section area of the component gases.

The Pressure Field at the Output From a Low Pressure Exhaust Hood and Condenser Neck of the 1090 MW Steam Turbine: Experimental and Numerical Research

2018 ◽  
Author(s):  
Michal Hoznedl ◽  
Antonín Živný ◽  
Aleš Macálka ◽  
Robert Kalista ◽  
Kamil Sedlák ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Steam Turbine ◽  
Cross Section ◽  
Static Pressure ◽  
Cooling Water ◽  
Low Pressure ◽  
Maximum Temperature ◽  
Angle Distribution ◽  
Exhaust Hood ◽  
Last Stage

The paper presents the results of measurements of flow parameters behind the last stage of a 1090 MW nominal power steam turbine in a nuclear power plant. The results were obtained by traversing a pneumatic probe at a distance of about 100 mm from the trailing edges of the LSB (Last Stage Blade). Furthermore, both side walls as well as the front wall of one flow of the LP (Low Pressure) exhaust hood were fitted with a dense net of static pressure taps at the level of the flange of the turbine. A total of 26 static pressures were measured on the wall at the output from the LP exhaust hood. Another 14 pressures were measured at the output from the condenser neck. The distribution of static pressures in both cross sections for full power and 600 and 800 MW power is shown. Another experiment was measured pressure and angle distribution using a ball pneumatic probe in the condenser neck area in a total of four holes at a distance up to 5 metres from the neck wall. The turbine condenser is two-flow design. In one direction perpendicular to the axis of the turbine cold cooling water comes, it heats partially. It then reverses and it heats to the maximum temperature again. The different temperature of cooling water in the different parts of the output cross section should influence the distribution of the output static pressure. Differences in pressures may cause problems with uneven load of the tube bundles of the condenser as well as problems with defining the influential edge output condition in CFD simulations of the flow of the cold end of the steam turbine Due to these reasons an extensive 3D CFD computation, which includes one stator blade as well as all moving blades of the last stage, a complete diffuser, the exhaust hood and the condenser neck, has been carried out. Geometry includes all reinforcing elements, pipes and heaters which could influence the flow behaviour in the exhaust hood and its pressure loss. Inlet boundary conditions were assumed for the case of both computations from the measurement of the flow field behind the penultimate stage. The outlet boundary condition was defined in the first case by an uneven value of the static pressure determined by the change of the temperature of cooling water. In the second case the boundary condition in accordance with the measurement was defined by a constant value of the static pressure along all the cross section of the output from the condenser neck. Results of both CFD computations are compared with experimental measurement by the distribution of pressures and other parameters behind the last stage.

scholarly journals Calculation of degassing networks taking into account the accumulation of the liquid phase

2019 ◽  
Vol 109 ◽  
pp. 00063
Author(s):  
Leonid Novikov ◽  
Oleksandr Bokii
Keyword(s):  
Liquid Phase ◽  
Cross Section ◽  
Liquid Surface ◽  
Geometric Parameters ◽  
Interfacial Friction ◽  
Gas Mixture ◽  
Dynamic Parameters ◽  
Fluid Accumulation ◽  
Gas Dynamic ◽  
Resistance Coefficients

The issue of accounting for the accumulation of liquid in the mine degassing network during gas-dynamic calculations is considered. Geometry of fluid accumulation in the cross section of degassing pipeline and the formulas for geometric parameters are presented. A scheme of wave generation on the liquid surface is considered. Dependence for the coefficient of resistance to interfacial friction on the liquid surface is proposed. Formulas for calculation of gas-dynamic parameters on the pipeline section are given. The results calculation of the resistance coefficients in the place accumulation of liquid, changes in flow and pressure of the gas mixture are presented. Calculations carried out for pipelines with accumulations of liquid.

Modeling for 3-D Temperature Field of Oil-Immersed Transformer

2011 ◽  
Vol 199-200 ◽  
pp. 1487-1491
Author(s):  
Su Xiang Qian ◽  
Ju Wu Xu ◽  
Xiao Jun Gu
Keyword(s):  
Temperature Field ◽  
Heat Exchange ◽  
Flow Field ◽  
Computer Experiment ◽  
Geometrical Model ◽  
Actual Situation ◽  
Traditional Methods ◽  
Ansys Cfx

The knowledge of temperature field of oil-filled transformer directly related to the judgment of overheated fault. There are mainly heat exchange, convection and their coupling in the transformer. Lot of traditional methods are not enough direct-viewing, and ignore the actual situation. The geometrical model of the transformer first modeled by Solidworks, and then ANSYS CFX is used to simulate the temperature field and flow field. Get a set of computer experiment result which can be reference. This computer experiment bring forth the method and effect of the simulate using that software, and make a foundation for the research of transformer overheated fault.

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