Estimation of time-dependent thermal boundary conditions and online reconstruction of transient temperature field for boiler membrane water wall

Author(s):  
Cai Lv ◽  
Guangjun Wang ◽  
Hong Chen
2013 ◽  
Vol 779-780 ◽  
pp. 958-964
Author(s):  
You Liu ◽  
Jing Jing Liu ◽  
Xiao Chen

By means of ANSYS, piston finite element model is constructed to attain transient numerical simulation and explore the characteristics of surface temperature. On the basis of experimental design, the correlation is analyzed between major boundary conditions and temperature of feature points, thus revealing the corresponding correlation of quantity. Transient calculation method is proved to be scientific and paves way to defining boundary conditions. And furthermore there forms a theoretical foundation for positioning test point in piston temperature field.


Author(s):  
Pingping Liu ◽  
Huijie Zhang ◽  
Guang Wen ◽  
Fangjun Zuo ◽  
Meiwei Jia

Abstract The hot-press fusing process of a laser printer is one of the principal causes for paper folding and bending deformation. In order to predict and control the deformation of paper, first, the following analysis method is proposed for the transient temperature field analysis of the continuous moving paper: discretizing the thermal analysis process, replacing the moving paper model with the moving heat source, and simulating the movement speed of paper by setting the flow boundary conditions. Second, taking the steady-state thermal calculation results of the printer in the standby mode as initial conditions, the temperature distribution characteristics of paper during the movement are obtained with the paper model placed in a whole-machine environment to analyze the transient temperature field. Third, using the method of multi-field coupling, the transient temperature field results of paper are taken as the external load of its static analysis to analyze the deformation of paper during the fusing process; therefore, the quantitative deformation results and deformation characteristics of paper after fusing are obtained. According to the results, more precise boundary conditions can be achieved by calculating the temperature field of paper in a whole-machine environment. The method of transient temperature field analysis for continuous moving objects proposed in this study can effectively simulate the movement process of paper. The results reveal the mechanism of paper wrinkle and bending deformation in the fusing process, which can be used to predict the conveying performance of paper and guide the design work of the printer.


2021 ◽  
Author(s):  
Ninh The Nguyen ◽  
John H Chujutalli

Abstract FEA-based Gaussian density heat source models were developed to study the effect of convective and radiative heat sinks on the transient temperature field predicted by the available approximate analytical solution of the purely conduction-based Goldak’s heat source. A new complex 3D Gaussian heat source model, incorporating all three modes of heat transfer, i.e., conduction, convection and radiation, has been developed as an extension of the Goldak heat source. Its approximate transient analytical solutions for this 3-D moving heat source were derived and numerically benchmarked with the available measured temperature & weld pool geometry data by Matlab programming with ~5 to 6 times faster than FEA-based simulation. The new complex 3D Gaussian heat source model and its approximate solution could significantly reduce the computing time in generating the transient temperature field and become an efficient alternative to extensive FEA-based simulations of heating sequences, where virtual optimisation of a melting heat source (i.e. used in welding, heating, cutting or other advanced manufacturing processes) is desirable for characterisation of material behaviour in microstructure evolution, melted pool, microhardness, residual stress and distortions.


2012 ◽  
Vol 538-541 ◽  
pp. 1837-1842 ◽  
Author(s):  
Long Zhi Zhao ◽  
Zi Wang ◽  
Xin Yan Jiang ◽  
Jian Zhang ◽  
Ming Juan Zhao

According to the characteristics of laser melt injection, a numerical model for a simplified 3D transient temperature field in molten pool was established using FLUENT software in this paper. In the model, many factors were considered such as liquid metal turbulence, latent heat of phase transformation and material thermo physical properties depending on temperature. The results show that the model can be developed well by FLUENT software. And the results also show that the driving force of the liquid metal flow mechanism.


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