Analysis of temporal and spatial temperature gradients at pronouncedly fluctuating cooling conditions

2004 ◽  
Vol 120 ◽  
pp. 529-535
Author(s):  
A. Galović ◽  
M. Andrassy ◽  
S. Mudrinić
Keyword(s):  
Control Volume ◽  
High Sensitivity ◽  
Cooling Capacity ◽  
Temperature Changes ◽  
Probe Diameter ◽  
Cooling Conditions ◽  
Calculation Results ◽  
Volume Method ◽  
Cooling Velocity ◽  
Very High

Realised cooling velocities of a probe (cylinder) at discrete radius points during cooling at pronouncedly fluctuating cooling conditions are presented. Submerging the probe into an air-corundum (Al2O3) particles fluidised system of insufficient cooling capacity imposes the fluctuating cooling conditions. The particles have an average granulation of 95 m; the cylindrical probe diameter is 50 mm and its height 175 mm. The probe surface temperature and the temperature 1.5 mm beneath its surface are measured with built-in thermocouples. The thermocouples have a very high sensitivity, which enables temperature variation recording according to the cooling dynamics. The relevant cooling time is 125 seconds. The temperature changes in discrete points of the cylinder radius are determined by the control volume method. The calculation results indicate a shift of the maximum cooling velocity towards the interior of the cylinder.

scholarly journals Numerical Simulation of Intrachamber Processes in the Power Plant

2021 ◽  
Vol 11 (11) ◽  
pp. 4990
Author(s):  
Boris Benderskiy ◽  
Peter Frankovský ◽  
Alena Chernova
Keyword(s):  
Numerical Simulation ◽  
Power Plant ◽  
Flow Structure ◽  
Power Plants ◽  
Control Volume ◽  
Conjugate Problem ◽  
Topological Features ◽  
Gas Dynamic ◽  
Calculation Results ◽  
Volume Method

This paper considers the issues of numerical modeling of nonstationary spatial gas dynamics in the pre-nozzle volume of the combustion chamber of a power plant with a cylindrical slot channel at the power plant of the mass supply surface. The numerical simulation for spatial objects is based on the solution conjugate problem of heat exchange by the control volume method in the open integrated platform for numerical simulation of continuum mechanics problems (openFoam). The calculation results for gas-dynamic and thermal processes in the power plant with a four-nozzle cover are presented. The analysis of gas-dynamic parameters and thermal flows near the nozzle cover, depending on the canal geometry, is given. The topological features of the flow structure and thermophysical parameters near the nozzle cap were studied. For the first time, the transformation of topological features of the flow structure in the pre-nozzle volume at changes in the mass channel’s geometry is revealed, described, and analyzed. The dependence of the Nusselt number in the central point of stagnation on the time of the power plants operation is revealed.

Research on the Design Process of Bellmouth Suction Passage of Vertical Pumping System

2009 ◽  
Author(s):  
Li Cheng ◽  
Chao Liu
Keyword(s):  
Design Process ◽  
Control Volume ◽  
Control Volume Method ◽  
Turbulent Model ◽  
Pumping System ◽  
Different Types ◽  
Calculation Results ◽  
Simplec Algorithm ◽  
Pump Sump ◽  
Volume Method

There are different types of suction box of vertical pumping system. In order to understand their relations and differences, the control volume method was used to simulate flow pattern of different suction boxes. The standard k-ε turbulent model and SIMPLEC algorithm were applied in solving the N-S equations. The steady calculation results indicated that the flow patterns of different suction boxes of vertical pumping system were similar to each other. The different kinds of suction boxes were evolved from the pump sump. They can be united if they have essentially the same controlled parameters. It is a useful idea for the design of suction box of vertical pumping system.

scholarly journals A New Formulation of Maxwell’s Equations

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 868
Author(s):  
Simona Fialová ◽  
František Pochylý
Keyword(s):  
Numerical Methods ◽  
Maxwell’S Equations ◽  
Maxwell's Equations ◽  
Control Volume ◽  
Control Volume Method ◽  
Integral Forms ◽  
New Formulation ◽  
Electrical Induction ◽  
Volume Method ◽  
Integral Identities

In this paper, new forms of Maxwell’s equations in vector and scalar variants are presented. The new forms are based on the use of Gauss’s theorem for magnetic induction and electrical induction. The equations are formulated in both differential and integral forms. In particular, the new forms of the equations relate to the non-stationary expressions and their integral identities. The indicated methodology enables a thorough analysis of non-stationary boundary conditions on the behavior of electromagnetic fields in multiple continuous regions. It can be used both for qualitative analysis and in numerical methods (control volume method) and optimization. The last Section introduces an application to equations of magnetic fluid in both differential and integral forms.

scholarly journals Effective Method for Diagnosing Continuous Welded Track Condition Based on Experimental Research

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2889
Author(s):  
Jacek Kukulski ◽  
Piotr Gołębiowski ◽  
Jacek Makowski ◽  
Ilona Jacyna-Gołda ◽  
Jolanta Żak
Keyword(s):  
Experimental Research ◽  
Thermal Stresses ◽  
Longitudinal Force ◽  
Climatic Conditions ◽  
Traffic Load ◽  
Empirical Formulas ◽  
Correct Operation ◽  
Temperature Changes ◽  
Track Condition ◽  
Very High

The correct operation of the continuous welded track requires diagnosing its condition and preparation of track metrics requiring measurements of displacements of rail under operation. This is required as there are additional thermal stresses in the rails with values depending on the temperature changes of the rails. Therefore, the climatic conditions are important. This paper presents the original effective analytical method for diagnosing the condition of continuous welded track based on experimental research. The method allows for an appropriate repair or maintenance recommendation. In the experimental research, the authors considered track diagnostic conditions for two conditions: track under load and track without load. This paper presents empirical formulas for calculating rail temperature and longitudinal force based on ambient temperature, developed from long-term measurements. The formulas were developed for a track located on a straight section—both for a rail loaded and unloaded with a passing train under the following conditions: 60E1 rail, not on an engineering structure, conventional surface, wooden sleepers and very high train traffic load. The obtained results in the value of the correlation coefficient R2 ≥ 0.995 attest to very high accuracy of the calculations performed with the method proposed by the authors.

Very high sensitivity optical modulators based on band filling effect in GaInAs quantum wells

1990 ◽  
Author(s):  
T.Y. Chang ◽  
J.E. Zucker ◽  
K.L. Jones ◽  
N.J. Sauer ◽  
B. Tell ◽  
...  
Keyword(s):  
Quantum Wells ◽  
High Sensitivity ◽  
Optical Modulators ◽  
Band Filling ◽  
Very High

Numerical prediction of the performance of gas-lubricated spiral groove thrust bearings

1997 ◽  
Vol 211 (2) ◽  
pp. 117-128 ◽  
Author(s):  
Y Yue ◽  
T. A. Stolarski
Keyword(s):  
Control Volume ◽  
Numerical Procedure ◽  
Operating Conditions ◽  
Hydrodynamic Bearings ◽  
Thrust Bearings ◽  
Flow Balance ◽  
Control Volumes ◽  
Volume Method ◽  
Spiral Angle ◽  
Spiral Grooves

The objective of this paper is to develop an accurate numerical procedure for the analysis of nominally flat contacts with spiral grooves lubricated by gases. The numerical procedure, which is based on the control-volume method, enables the solutions of the non-linear Reynolds equation to be obtained without limitation in geometry and operating conditions. Satisfactory flow balance was achieved on the control volumes as well as on the whole boundary and the method was proved to be very accurate. Convergence of the method was quick for any compressibility number. Three types of contact with spiral grooves were analysed. They were hydrodynamic bearings without interior chambers, hydrodynamic bearings with interior chambers and hybrid bearings. The effects of spiral angle, groove geometry (length, depth and width) and compressibility on performances were investigated for all possible designs.

Effect of Periodic Imposed Heat Flux on Three-Dimensional Natural Convection in a Partially Heated Cubical Enclosure

2016 ◽  
Vol 831 ◽  
pp. 83-91
Author(s):  
Lahoucine Belarche ◽  
Btissam Abourida
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Study ◽  
Control Volume ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Cubical Enclosure ◽  
Simplec Algorithm ◽  
Volume Method

The three-dimensional numerical study of natural convection in a cubical enclosure, discretely heated, was carried out in this study. Two heating square sections, similar to the integrated electronic components, are placed on the vertical wall of the enclosure. The imposed heating fluxes vary sinusoidally with time, in phase and in opposition of phase. The temperature of the opposite vertical wall is maintained at a cold uniform temperature and the other walls are adiabatic. The governing equations are solved using Control volume method by SIMPLEC algorithm. The sections dimension ε = D / H and the Rayleigh number Ra were fixed respectively at 0,35 and 106. The average heat transfer and the maximum temperature on the active portions will be examined for a given set of the governing parameters, namely the amplitude of the variable temperatures a and their period τp. The obtained results show significant changes in terms of heat transfer, by proper choice of the heating mode and the governing parameters.

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