scholarly journals Comparison of Two Models for Radiative Heat Transfer in High Temperature Thermal Plasmas

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Matthieu Melot ◽  
Jean-Yves Trépanier ◽  
Ricardo Camarero ◽  
Eddy Petro
Keyword(s):  
High Temperature ◽  
Radiative Transfer ◽  
Radiative Heat ◽  
Critical Role ◽  
Critical Evaluation ◽  
Thermal Plasmas ◽  
Test Cases ◽  
Circuit Breakers ◽  
Cfd Simulations ◽  
Volume Method

Numerical simulation of the arc-flow interaction in high-voltage circuit breakers requires a radiation model capable of handling high-temperature participating thermal plasmas. The modeling of the radiative transfer plays a critical role in the overall accuracy of such CFD simulations. As a result of the increase of computational power, CPU intensive methods based on the radiative transfer equation, leading to more accurate results, are now becoming attractive alternatives to current approximate models. In this paper, the predictive capabilities of the finite volume method (RTE-FVM) and the P1 model are investigated. A systematic comparison between these two models and analytical solutions are presented for a variety of relevant test cases. Two implementations of each approach are compared, and a critical evaluation is presented.

scholarly journals Benchmark Solutions of Three-Dimensional Radiative Transfer in Nongray Media Using Line-by-Line Integration

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Guilherme C. Fraga ◽  
Hadi Bordbar ◽  
Simo Hostikka ◽  
Francis H. R. França
Keyword(s):  
Radiative Transfer ◽  
Radiative Heat ◽  
Pure Water ◽  
Three Dimensional ◽  
Quality Analysis ◽  
Gas Radiation ◽  
Mesh Independence ◽  
Spectroscopic Database ◽  
Volume Method ◽  
Benchmark Solutions

Abstract Nongray gas radiation calculations are conducted for four three-dimensional benchmarks using line-by-line (LBL) integration with the up-to-date high-resolution spectroscopic database HITEMP 2010. The radiative transfer equation (RTE) is solved using the finite volume method (FVM) over each wavenumber interval of the spectrum. A detailed mesh quality analysis assured the mesh independence of the solution. Accurate results for distributions of volumetric radiative heat source term and wall radiative heat flux are provided for four cases: (i) an isothermal pure water vapor medium at 1000 K; (ii) an isothermal and nonhomogeneous H2O–N2 mixture at 1000 K; (iii) a nonisothermal and homogeneous CO2–H2O–N2 mixture; and (iv) a nonisothermal and nonhomogeneous CO2–H2O–N2 mixture. These data can be useful to assess the accuracy of gas radiative property models.

Analytical Solution Under Two-Flux Approximation to Radiative Heat Transfer in Absorbing Emitting and Anisotropically Scattering Medium

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Xin-Lin Xia ◽  
Dong-Hui Li ◽  
Feng-Xian Sun
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Radiative Transfer ◽  
Analytical Solution ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Thermal Protection ◽  
Isotropic Scattering ◽  
Scattering Media ◽  
Flux Approximation

Radiative transfer in absorbing, emitting, and highly anisotropically scattering media is widely encountered in high temperature applications such as pulverized coal firing furnaces and high temperature thermal protection materials. Efficient and effective solution methods for the transfer process are very crucial, especially in thermal radiation related reverse problems and optimization designs. In this study, the analytical solution for radiative heat transfer in an absorbing, emitting, and anisotropically scattering slab between two parallel gray walls are derived under the two-flux approximation. Explicit expression for the radiative heat flux in a slab is obtained under two-flux approximation. The reliability and adaptability of an analytical solution is examined in case studies by comparing with the Monte Carlo results. Comparative studies indicate that the analytical solution can be used in radiative transfer calculation in an absorbing emitting and anisotropically scattering slab. It is much more applicable in a forward and isotropic scattering slab than in an absorbing one, especially in a forward scattering slab. Because of simplicity and high computing efficiency with the analytical solution, it may be useful in reverse radiative transfer problems, in optimization design, and in developing some numerical schemes on radiative heat transfer.

Line-by-Line Random-Number Database for Monte Carlo Simulations of Radiation in Combustion System

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Tao Ren ◽  
Michael F. Modest
Keyword(s):  
Heat Transfer ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Radiative Heat ◽  
Random Number ◽  
Test Cases ◽  
Combustion System ◽  
Absorption Coefficients ◽  
One Dimensional ◽  
The Monte Carlo Method

With today's computational capabilities, it has become possible to conduct line-by-line (LBL) accurate radiative heat transfer calculations in spectrally highly nongray combustion systems using the Monte Carlo method. In these calculations, wavenumbers carried by photon bundles must be determined in a statistically meaningful way. The wavenumbers for the emitting photons are found from a database, which tabulates wavenumber–random number relations for each species. In order to cover most conditions found in industrial practices, a database tabulating these relations for CO2, H2O, CO, CH4, C2H4, and soot is constructed to determine emission wavenumbers and absorption coefficients for mixtures at temperatures up to 3000 K and total pressures up to 80 bar. The accuracy of the database is tested by reconstructing absorption coefficient spectra from the tabulated database. One-dimensional test cases are used to validate the database against analytical LBL solutions. Sample calculations are also conducted for a luminous flame and a gas turbine combustion burner. The database is available from the author's website upon request.

Study on Superalloy Tube Extrusion Process Using Finite Volume Method

2012 ◽  
Vol 572 ◽  
pp. 267-272
Author(s):  
Yi Lun Mao ◽  
Qing Dong Zhang ◽  
Chao Yang Sun ◽  
Xiao Feng Zhang
Keyword(s):  
Mathematical Model ◽  
High Temperature ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Extrusion Process ◽  
Equivalent Strain ◽  
High Temperature Alloy ◽  
Squeeze Pressure ◽  
Tube Extrusion ◽  
Volume Method

In this paper, complexity of the process of high temperature alloy tubing extrusion is studied using the Finite Volume Method (FVM). We establish mathematical model of high temperature alloy tube extrusion process by using the Finite Volume Method. We develop the simulation program by the control equation of the Finite Volume Method and numerical simulation of the key technologies of the axisymmetric problem in cylindrical coordinates. Inconel690 high temperature alloy tubing extrusion process, for example, we got the squeeze pressure in the steady-state extrusion, Velocity field and the corresponding equivalent strain rate field. By comparing the results obtained by the finite volume method and simulation results from Finite Element Method (FEM) software on DEFORM-2D, we find our mathematical model on high temperature alloy tubing extrusion process is reasonable and correct.

scholarly journals Evaluation of Upper Indus Near-Surface Climate Representation by WRF in the High Asia Refined Analysis

2019 ◽  
Vol 20 (3) ◽  
pp. 467-487 ◽  
Author(s):  
David M. W. Pritchard ◽  
Nathan Forsythe ◽  
Hayley J. Fowler ◽  
Greg M. O’Donnell ◽  
Xiao-Feng Li
Keyword(s):  
Regional Climate ◽  
Critical Role ◽  
Critical Evaluation ◽  
Longwave Radiation ◽  
Indus Basin ◽  
Shortwave Radiation ◽  
Cold Bias ◽  
Near Surface ◽  
High Asia ◽  
High Bias

Abstract Data paucity is a severe barrier to the characterization of Himalayan near-surface climates. Regional climate modeling can help to fill this gap, but the resulting data products need critical evaluation before use. This study aims to extend the appraisal of one such dataset, the High Asia Refined Analysis (HAR). Focusing on the upper Indus basin (UIB), the climatologies of variables needed for process-based hydrological and cryospheric modeling are evaluated, leading to three main conclusions. First, precipitation in the 10-km HAR product shows reasonable correspondence with most in situ measurements. It is also generally consistent with observed runoff, while additionally reproducing the UIB’s strong vertical precipitation gradients. Second, the HAR shows seasonally varying bias patterns. A cold bias in temperature peaks in spring but reduces in summer, at which time the high bias in relative humidity diminishes. These patterns are concurrent with summer overestimation (underestimation) of incoming shortwave (longwave) radiation. Finally, these seasonally varying biases are partly related to deficiencies in cloud, snow, and albedo representations. In particular, insufficient cloud cover in summer leads to the overestimation of incoming shortwave radiation. This contributes to the reduced cold bias in summer by enhancing surface warming. A persistent high bias in albedo also plays a critical role, particularly by suppressing surface heating in spring. Improving representations of cloud, snow cover, and albedo, and thus their coupling with seasonal climate transitions, would therefore help build upon the considerable potential shown by the HAR to fill a vital data gap in this immensely important basin.

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