On the Reduction of Wall Temperature Non-Uniformity of a Three-Dimensional Experimental Apparatus

2009 ◽  
Author(s):  
P. Y. C. Lee ◽  
W. H. Leong
Keyword(s):  
Heat Source ◽  
Temperature Difference ◽  
Mathematical Analysis ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Measured Temperature ◽  
Uniform Temperature ◽  
Original Design ◽  
Experimental Apparatus ◽  
Detailed Mathematical Analysis

This paper presents a detailed analysis that was performed for the design of a “uniform” temperature boundary condition imposed on a boundary of a three-dimensional cubical experimental apparatus for benchmark natural convection heat transfer study. The three-dimensional experimental apparatus was constructed with plates which were assembled to act as boundary conditions to the enclosure walls. Test measurements revealed that temperature non-uniformity along one of the plates (boundary) was significant enough that the benchmark study could not be carried out to the desired accuracy of about 1% error. A subsequent detailed mathematical analysis revealed that the temperature non-uniformity on the plate was a result of the effect of thermal spreading/constriction resistance. Modifications to the original design of the apparatus were made to reduce the temperature non-uniformity on the plate by adding a heat source around the plate where the uniform temperature setting was desired. Before the addition of this heat source, a careful mathematical analysis shows a significant reduction in temperature non-uniformity from about 4% (based on the initial design) to less than 1% (for the modified design). By examining the temperature difference between two locations on the plate, the predicted temperature difference obtained through mathematical analyses show excellent agreement with the measured temperature difference.

Final Design Parameter Settings for a Physically-Realizable Uniform Temperature Boundary Condition Specification on a Wall of an Enclosure

2013 ◽  
Author(s):  
P. Y. C. Lee ◽  
W. H. Leong
Keyword(s):  
Boundary Condition ◽  
Natural Convection ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Design Parameters ◽  
Uniform Temperature ◽  
Original Design ◽  
Temperature Boundary ◽  
Contact Width ◽  
Temperature Boundary Condition

Design parameters based on a three-dimensional internal natural convection heat transfer in a cubical apparatus are presented so that a uniform temperature boundary condition specification on a wall of the apparatus can be physically achieved. Preliminary temperature measurements based on the initial design of the apparatus where the uniform boundary condition was prescribed revealed that a temperature non-uniformity existed in the excess of 4% error. In order to complete the objective of the benchmark internal natural convection study, the apparatus had to be modified so that the temperature non-uniformity can be reduced to less than 1% error. It was decided that the original design be modified by simply adding two auxiliary heaters in the vicinity of the wall where the uniform temperature profile was desired. Before the implementation of the auxiliary heaters onto the apparatus, a detailed mathematical analysis was conducted to determine the position and the contact width of the heaters, and to establish an appropriate heat flux required to reduce the temperature non-uniformity to less than 1% along the wall of the apparatus. This analysis was achieved by using the approximate analytical temperature solution obtained from the boundary value problem of a plate (which is one part of the apparatus) with boundary conditions prescribed to model the auxiliary heaters. Previously, a specific set of design parameters were used that reduced the temperature non-uniformity to less than 1% along a wall of the modified cubical apparatus. As an extension to the previous work, this paper presents a generalized set of design parameters that can equally prescribe a physically-realizable uniform temperature setting along a wall of an enclosure to within 1% error. With the range of design parameters, this would enable any designer with the flexibility in choosing what parameters can be allocated based on their need.

Numerical Simulation to the Temperature Distribution of the Laser Cladding

2014 ◽  
Vol 800-801 ◽  
pp. 843-846 ◽  
Author(s):  
Liang Zhou ◽  
Xi Chen ◽  
Bo Zhu
Keyword(s):  
Numerical Simulation ◽  
Heat Source ◽  
Laser Cladding ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Transient Temperature ◽  
Main Technique ◽  
Dimensional Finite Element ◽  
Laser Heat Source ◽  
Three Dimensional Finite Element

Numerical simulation to the temperature of laser cladding can simulate the process of its technique, which can also optimize the parameters of the technique and predict the defects of the cladding. In this paper, a three-dimensional finite element powder-feed laser single cladding model of the transient temperature field was built based on APDL in ANSYS, where the Gaussian distribution of heat source, forced convection heat transfer and the motion of laser heat source are simulated .The results reveal how the main technique parameters affect the distribution of the temperature, and make a prepare for the experiment of laser cladding.

Heat Transfer in a Horizontal Water Layer with Radiative Heating

1972 ◽  
Vol 1 (4) ◽  
pp. 213-218 ◽  
Author(s):  
R.R. Gilpin
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Convection Heat Transfer ◽  
Water Layer ◽  
Short Wave ◽  
Horizontal Layer ◽  
Heat Fluxes ◽  
Radiative Heating ◽  
Temperature Boundary ◽  
Experimental Apparatus

The effect of short-wave radiative heating on the temperature distribution and heat fluxes in a horizontal layer of water was studied. A power law expression was developed for modelling the form of the distributed heat source produced by the absorbed radiation. Also an experimental apparatus was devised in which predictions based on the assumed form of the heat source could be compared with measured values. In the cases studied steady state conditions existed with prescribed temperature boundary conditions. Both conduction and convection heat transfer were found to be important in the water layer.

Density waves in disk galaxies

1967 ◽  
Vol 31 ◽  
pp. 313-317 ◽  
Author(s):  
C. C. Lin ◽  
F. H. Shu
Keyword(s):  
Mathematical Analysis ◽  
Spiral Structure ◽  
Stellar System ◽  
Collective Modes ◽  
Disk Galaxies ◽  
Spiral Pattern ◽  
Density Waves ◽  
The Galaxy ◽  
Detailed Mathematical Analysis

Density waves in the nature of those proposed by B. Lindblad are described by detailed mathematical analysis of collective modes in a disk-like stellar system. The treatment is centered around a hypothesis of quasi-stationary spiral structure. We examine (a) the mechanism for the maintenance of this spiral pattern, and (b) its consequences on the observable features of the galaxy.

scholarly journals Structural Health Monitoring of 2D Plane Structures

2021 ◽  
Vol 11 (5) ◽  
pp. 2000
Author(s):  
Behnam Mobaraki ◽  
Haiying Ma ◽  
Jose Antonio Lozano Galant ◽  
Jose Turmo
Keyword(s):  
Mechanical Properties ◽  
Health Monitoring ◽  
Mathematical Analysis ◽  
Stiffness Matrix ◽  
State Of The Art ◽  
System Of Equations ◽  
Matrix System ◽  
Structural System ◽  
Detailed Mathematical Analysis ◽  
Structural System Identification

This paper presents the application of the observability technique for the structural system identification of 2D models. Unlike previous applications of this method, unknown variables appear both in the numerator and the denominator of the stiffness matrix system, making the problem non-linear and impossible to solve. To fill this gap, new changes in variables are proposed to linearize the system of equations. In addition, to illustrate the application of the proposed procedure into the observability method, a detailed mathematical analysis is presented. Finally, to validate the applicability of the method, the mechanical properties of a state-of-the-art plate are numerically determined.

A Transient Simulation of Heated Soil Vapor Extraction System

Volume 1 ◽  
2004 ◽  
Author(s):  
T. Roy ◽  
R. S. Amano ◽  
J. Jatkar
Keyword(s):  
Heat Source ◽  
Three Dimensional ◽  
Soil Vapor Extraction ◽  
Extraction System ◽  
Vapor Extraction ◽  
Predictive Tool ◽  
Heating Source ◽  
Time Required ◽  
Heated Soil ◽  
Remediation Process

Soil remediation process by heated soil vapor extraction system has drawn considerably attention for the last few years. The areas around chemical companies or waste disposal sites have been seriously contaminated from the chemicals and other polluting materials that are disposed off. Our present study is concentrated on modeling one transient Heated Soil Vapor Extraction System and predicting the time required for effective remediation. The process developed by Advanced Remedial Technology, consists of a heating source pipe and the extraction well embedded in the soil. The number of heat source pipes and the extraction wells depends on the type of soil, the type of pollutants, moisture content of the soil and the size of the area to be cleaned. The heat source heats the soil, which is transported in the interior part of the soil by means of conduction and convection. This heating of soil results in vaporization of the gases, which are then driven out of the soil by the extraction well. The extraction well consists of the blower which would suck the vaporized gases out of the system. A three-dimensional meshed geometry was developed using gambit. Different boundary conditions were used for heating and suction well and for other boundaries. Concentrations of different chemicals were collected from the actual site and this data was used as an initial condition. The analysis uses the species transport and discrete phase modeling to predict the time required to clean the soil under specific conditions. This analysis could be used for predicting the changes of chemical concentrations in the soil during the remediation process. This will give us more insight to the physical phenomena and serve as a numerical predictive tool for more efficient process.

Design of an Intermediate Turbine Duct Downstream of a High Pressure Turbine

2016 ◽  
Author(s):  
Chaoshan Hou ◽  
Hu Wu
Keyword(s):  
High Pressure ◽  
Three Dimensional ◽  
Low Pressure ◽  
Aerodynamic Load ◽  
Duct Flow ◽  
Original Design ◽  
High Pressure Turbine ◽  
Intermediate Turbine Duct ◽  
Low Pressure Turbine ◽  
Inlet Conditions

The flow leaving the high pressure turbine should be guided to the low pressure turbine by an annular diffuser, which is called as the intermediate turbine duct. Flow separation, which would result in secondary flow and cause great flow loss, is easily induced by the negative pressure gradient inside the duct. And such non-uniform flow field would also affect the inlet conditions of the low pressure turbine, resulting in efficiency reduction of low pressure turbine. Highly efficient intermediate turbine duct cannot be designed without considering the effects of the rotating row of the high pressure turbine. A typical turbine model is simulated by commercial computational fluid dynamics method. This model is used to validate the accuracy and reliability of the selected numerical method by comparing the numerical results with the experimental results. An intermediate turbine duct with eight struts has been designed initially downstream of an existing high pressure turbine. On the basis of the original design, the main purpose of this paper is to reduce the net aerodynamic load on the strut surface and thus minimize the overall duct loss. Full three-dimensional inverse method is applied to the redesign of the struts. It is revealed that the duct with new struts after inverse design has an improved performance as compared with the original one.

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