Journal articles on the topic 'Transient thermal simulations'
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1
Hahn, Luzia, and Peter Eberhard. "Transient Dynamical-Thermal-Optical System Modeling and Simulation." EPJ Web of Conferences 238 (2020): 12001. http://dx.doi.org/10.1051/epjconf/202023812001.
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In this work, methods and procedures are investigated for the holistic simulation of the dynamicalthermal behavior of high-performance optics like lithography objectives. Flexible multibody systems in combination with model order reduction methods, finite element thermal analysis and optical system analyses are used for transient simulations of the dynamical-thermal behavior of optical systems at low computational cost.
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Julianto, Eko, Waluyo Adi Siswanto, and Pebli Hardi. "Thermal Transient and Thermal Stress on Radiated Heat Float Glass." JSE Journal of Science and Engineering 1, no. 1 (January 31, 2020): 1–6. http://dx.doi.org/10.30650/jse.v1i1.150.
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To conduct an experiment of thermal radiation. The researchers conducted a simulation to study the behavior of the damage float glass using Mecway 10 FEA software. The ambient time and temperature on the first float glass sheet sustaining thermal transient and thermal stress are the most important parameters to find out the part of float glass. Analyzing the results of all simulations of radiant heat and convection in transient thermal simulations on the surface of float glass to be crack and knowing the estimated time until cracked float glass with thermal stress analysis. Giving heat radiation to the exposed glass surface, to be assumed by heat exposure from 0 to 20 minutes which is 32º to 600ºC with 19 mm glass thickness using Mecway 10 FEA software. Then did a comparison of the radiation heat value convection flow rate and so that the glass experiences a thermal crack. In this process, the results of the comparison will also be reviewed and discussed at the limit of the amount of heat radiation so that the cracked glass or thermal crack. The difference in temperature and stress will increase with adding radiation heat on the glass. Critical time and temperature differences are given as reference values to predict Thermal stress in computerized applications.
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Faucher, Margaux, Davide Mancusi, and Andrea Zoia. "MULTI-PHYSICS TRANSIENT SIMULATIONS WITH TRIPOLI-4®." EPJ Web of Conferences 247 (2021): 07019. http://dx.doi.org/10.1051/epjconf/202124707019.
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In this work, we present the first dynamic calculations performed with the Monte Carlo neutron transport code TRIPOLI-4R with thermal-hydraulics feedback. For this purpose, the Monte Carlo code was extended for multi-physics capabilities and coupled to the thermal-hydraulics subchannel code SUBCHANFLOW. As a test case for the verification of transient simulation capabilities, a 3x3-assembly mini-core benchmark based on the TMI-1 reactor is considered with a pin-by-pin description. Two reactivity excursion scenarios initiated by control-rod movement are simulated starting from a critical state and compared to analogous simulations performed using the Serpent 2 Monte-Carlo code. The time evolution of the neutron power, fuel temperature, coolant temperature and coolant density are analysed to assess the multi-physics capabilities of TRIPOLI-4. The stabilizing e_ects of thermal-hydraulics on the neutron power appear to be well taken into account. The computational requirements for massively parallel calculations are also discussed.
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Huang, Yaren, Benedikt Lechner, and Gerhard Wachutka. "Comparative Numerical Analysis of the Robustness of Si and SiC PiN Diodes Against Cosmic Radiation-Induced Failure." Materials Science Forum 1004 (July 2020): 1088–96. http://dx.doi.org/10.4028/www.scientific.net/msf.1004.1088.
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This work aims at extending the predictive simulation technique for cosmic ray-induced failure analysis from Si PiN diodes [1] to SiC PiN diodes. Accurate 3D cylindrical-symmetric transient simulations were performed with a minimum mesh size of 20nm at the center track of the impinging ion and a maximum time step of 0.1ps during the development of the ion-induced transient current. We made a comparative study between a SiC PiN diode and a Si PiN diode with the same blocking voltage of 1.5kV, using the same heavy ion transportation models. In the simulation, we observed different ion-induced current transients, differing not only in the peak value of the current, but also in its duration. Due to different physical mechanisms, the dependence of the ion-induced current on the reverse pre-bias voltage and the numerical mesh adaptations are also different. Eventually, we brieflydiscuss electro-thermal simulations, which indicate once more that the ion-induced transient current in the SiC PiN diodes under consideration is primarily drift current and involves only negligible impact ionization.
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Holdampf, Sydney A., Andrew G. Osborne, and Mark R. Deinert. "Method to Estimate Thermal Transients in Reactors and Determine Their Parameter Sensitivities without a Forward Simulation." Energies 15, no. 19 (September 24, 2022): 7027. http://dx.doi.org/10.3390/en15197027.
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Thermal response time is an important parameter for the control of fast reactors. Modern thermal hydraulic codes allow for the modeling of transient responses and can also be used to understand the dominant factors that affect them. However, simulations can be computationally expensive, particularly for performing parametric analyses of how thermophysical properties affect transient behavior. Here, we present a method for using linear stability analysis to estimate thermal response time and determine the key parameters that affect transient behavior without performing a forward simulation. The approach can also be used to corroborate simulation results and is tested against simulation results produced with a 2D finite difference model. The results show that this approach produces time-dependent temperature profiles that are within 2 × 10−5–0.1% of the numerical results for a single node perturbation. Changes in temperature have the greatest effect on thermal response time, followed by changes to thermal conductivity.
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Vasilev, Aleksandr, Tommy Lorenz, and Cornelia Breitkopf. "Thermal Conductivity of Polyisoprene and Polybutadiene from Molecular Dynamics Simulations and Transient Measurements." Polymers 12, no. 5 (May 9, 2020): 1081. http://dx.doi.org/10.3390/polym12051081.
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The thermal conductivities of untreated polyisoprene and polybutadiene were calculated by molecular dynamics (MD) simulations using a Green-Kubo approach between −10 °C and 50 °C at atmospheric pressure. For comparison, the thermal conductivities of untreated polyisoprene with a molecular weight of 54,000 g/mol and untreated polybutadiene with a molecular weight of 45,000 g/mol were measured by the transient hot wire method in similar conditions. The simulation results of both polymers are in good agreement with the experimental data. We observed that the MD simulations slightly overestimate the thermal conductivity due to the chosen force field description. Details are discussed in the paper.
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Baddour, R. E. "Computer simulation of ice control with thermal-bubble plumes — line source configuration." Canadian Journal of Civil Engineering 17, no. 4 (August 1, 1990): 509–13. http://dx.doi.org/10.1139/l90-058.
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Thermal-bubble plumes in a freshwater environment are studied to determine their ice control capabilities. A computer model is developed to optimize the operation of thermal-bubble installations when designed to control ice. Steady-state and transient simulations of ice control are presented. It is conceivable to fully computerize the operation of thermal-bubble installations by combining data acquisition, data analysis, computer simulation, and control automation. Key words: ice control, ice management, thermal-bubble plume, computer simulation.
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Abdi, Ammar, Youcef Ouazir, Georges Barakat, and Yacine Amara. "Transient quasi-3D magneto-thermal analytical solution in PM induction heating device." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 39, no. 5 (May 23, 2020): 1131–44. http://dx.doi.org/10.1108/compel-01-2020-0054.
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Purpose This paper aims to develop a new quasi-three dimensional (3D) analytical model devoted to the study of nonlinear transient magneto-thermal coupled problems in permanent magnet (PM) transverse flux induction heating device (TFIHD). Design/methodology/approach The presented work is based on analytical development of strongly coupled problem, including electromagnetic and thermal boundary problems. The electromagnetic problem is first solved by using the separation variables method to evaluate the induced currents in the nonmagnetic plate and the resulting power density loss distribution. The plate temperature profile is then obtained thanks to strong involvement of this magnetic model in a new analytical thermal model combining the separation of variables method and the Green’s functions transient regime analysis method. The coupled model is then used in a simulation procedure of the magneto-thermal process allowing taking into account the workpiece electrothermal nonlinear properties. The developed coupled model is validated by computing the performances of the studied PM TFIHD and comparing them to those obtained by finite element simulations. Finding An efficient transient quasi-3D magneto-thermal analytical model is developed allowing rapid analysis of PM induction heating for core heating of parallelepiped parts. The developed model also allows fast and accurate simulations of nonlinear and transient three dimensional (3D) magneto-thermal phenomena for planar induction heaters. Research limitations implications The developed quasi-3D magneto-thermal analytical model is limited to design induction heating devices of planar structure with PM inductors. Originality/value A new transient quasi-3D magneto-thermal analytical model accounts for non-linearity and edge effect and helps to fast study and fast design of linear permanent magnet induction heating device.
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Reis, Patrícia A. L., Antonella L. Costa, Claubia Pereira, Maria Auxiliadora F. Veloso, and Amir Z. Mesquita. "Simulation of a TRIGA Reactor Core Blockage Using RELAP5 Code." Science and Technology of Nuclear Installations 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/354163.
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Cases of core coolant flow blockage transient have been simulated and analysed for the TRIGA IPR-R1 research reactor using the RELAP5-MOD3.3 code. The transients are related to partial and to total obstruction of the core coolant channels. The reactor behaviour after the loss of flow was analysed as well as the changes in the coolant and fuel temperatures. The behaviour of the thermal hydraulic parameters from the transient simulations was analysed. For a partial blockage, it was observed that the reactor reaches a new steady state operation with new values for the thermal hydraulic parameters. The total core blockage brings the reactor to an abnormal operation causing increase in core temperature.
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Hua, Yu-Chao, and Bing-Yang Cao. "Transient in-plane thermal transport in nanofilms with internal heating." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2186 (February 2016): 20150811. http://dx.doi.org/10.1098/rspa.2015.0811.
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Wide applications of nanofilms in electronics necessitate an in-depth understanding of nanoscale thermal transport, which significantly deviates from Fourier's law. Great efforts have focused on the effective thermal conductivity under temperature difference, while it is still ambiguous whether the diffusion equation with an effective thermal conductivity can accurately characterize the nanoscale thermal transport with internal heating. In this work, transient in-plane thermal transport in nanofilms with internal heating is studied via Monte Carlo (MC) simulations in comparison to the heat diffusion model and mechanism analyses using Fourier transform. Phonon-boundary scattering leads to larger temperature rise and slower thermal response rate when compared with the heat diffusion model based on Fourier's law. The MC simulations are also compared with the diffusion model with effective thermal conductivity. In the first case of continuous internal heating, the diffusion model with effective thermal conductivity under-predicts the temperature rise by the MC simulations at the initial heating stage, while the deviation between them gradually decreases and vanishes with time. By contrast, for the one-pulse internal heating case, the diffusion model with effective thermal conductivity under-predicts both the peak temperature rise and the cooling rate, so the deviation can always exist.
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Oukaira, Aziz, Amrou Zyad Benelhaouare, Dariush Amirkhani, Jamal Zbitou, and Ahmed Lakhssassi. "Silicon Die Transient Thermal Peak Prediction Approach." ITM Web of Conferences 48 (2022): 02007. http://dx.doi.org/10.1051/itmconf/20224802007.
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It is well known that Field Programmable Gate Arrays (FPGA) are good platforms for implementing embedded systems because of their configurable nature. However, the temperature of FPGAs is becoming a serious concern. Improvements in manufacturing technology led to increased logic density in integrated circuits as well as higher clock frequencies. As logic density increases, so do power density, which in turn increases the temperature, FPGAs follow the same path. A prediction of the thermal state of the Altera Cyclone V System-on-Chip (SoC) is presented in this work. The prediction study employs a numerical technique called Finite Element Method (FEM), which is a discretization method to approximate the real solution of the Partial Differential Equation (PDE) for heat transfer around the board's critical sources. The DE1 5CSEMA5F31C6N board was simulated using the COMSOL Multiphysics® tool for predicting thermal peaks during 13 hours of normal operation. Using the NISA tool, we obtained very similar results to those previously obtained with a margin of error of 2 %. As a result, a Verilog code implementation that describes the same approach used by the last two simulation tools is uploaded to the FPGA to verify the results of these simulations. This paper provides a more accurate vision of the level of operating stability of our FPGA board, which are currently the most important source for prototyping and designing the world's largest systems.
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Wang, Tae Joong, Duk Sang Kim, and Tae Shik Ahn. "Simulation study on improving the selective catalytic reduction efficiency by using the temperature rise in a non-road transient cycle." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, no. 6 (August 29, 2016): 810–27. http://dx.doi.org/10.1177/0954407016664620.
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In this study, the transient nitrogen oxide reduction performance of a urea selective catalytic reduction system installed on a non-road diesel engine was tested on an engine dynamometer bench over a scheduled non-road transient cycle mode. Based on the measurement results, the characteristics of the transient selective catalytic reduction behaviours of nitrogen oxide reduction were evaluated. Also, in this study, the effects of several thermal management strategies for improving the selective catalytic reduction efficiency was investigated by transient selective catalytic reduction simulations. The kinetic parameters of the current simulation code for selective catalytic reduction were calibrated and validated by comparison with the measurement data. As a result of this study, it was found that a thermal management strategy utilizing a partial temperature rise in the transient time domain can be an efficient approach for improving the transient selective catalytic reduction efficiency, in comparison with the temperature rise over the entire cycle period. Furthermore, this study can provide some guideline data for the magnitude and the duration of the temperature rise required to obtain the target selective catalytic reduction efficiency over the non-road transient cycle mode. In the last part of this study, the impact of the variation in the space velocity on the transient selective catalytic reduction efficiency was assessed using transient selective catalytic reduction simulations.
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Tauveron, Nicolas, Manuel Saez, Muriel Marchand, Thierry Chataing, Geneviève Geffraye, and Christophe Bassi. "Transient thermal–hydraulic simulations of direct cycle gas cooled reactors." Nuclear Engineering and Design 235, no. 23 (December 2005): 2527–45. http://dx.doi.org/10.1016/j.nucengdes.2005.05.033.
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Degen, Denise, and Mauro Cacace. "Effects of transient processes for thermal simulations of the Central European Basin." Geoscientific Model Development 14, no. 3 (March 26, 2021): 1699–719. http://dx.doi.org/10.5194/gmd-14-1699-2021.
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Abstract. Transient processes play a major role in geophysical applications. In this paper, we quantify the significant influence arising from transient processes for conductive heat transfer problems for sedimentary basin systems. We demonstrate how the thermal properties are affected when changing the system from a stationary to a non-stationary (transient) state and what impact time-dependent boundary conditions (as derived from paleoclimate information) have on the system's overall response. Furthermore, we emphasize the importance of the time-stepping approach adopted to numerically solve for the transient case and the overall simulation duration since both factors exert a direct influence on the sensitivities of the thermal properties. We employ global sensitivity analyses to quantify not only the impact arising from the thermal properties but also their parameter correlations. Furthermore, we showcase how the results of such sensitivity analysis can be used to gain further insights into the complex Central European Basin System in central and northern Europe. This computationally very demanding workflow becomes feasible through the construction of high-precision surrogate models based on the reduced basis (RB) method.
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Soares, Humberto V., Ivan D. Aronne, Antonella L. Costa, Claubia Pereira, and Maria Auxiliadora F. Veloso. "Analysis of Loss of Flow Events on Brazilian Multipurpose Reactor Using the Relap5 Code." International Journal of Nuclear Energy 2014 (June 3, 2014): 1–12. http://dx.doi.org/10.1155/2014/186189.
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This work presents the thermal hydraulic simulation of the Brazilian multipurpose reactor (RMB) using a RELAP5/MOD3.3 model. Beyond steady state calculations, three transient cases of loss of flow accident (LOFA) in the primary cooling system have been simulated. The RELAP5 simulations demonstrate that after all initiating events, the reactor reaches a safe new steady state keeping the integrity and safety of the core. Moreover, a sensitivity study was performed to verify the nodalization behavior due to the variation of the thermal hydraulic channels in the reactor core. Transient calculations demonstrate that both nodalizations follow approximately the same behavior.
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Saavedra, J., G. Paniagua, and S. Lavagnoli. "On the transient response of the turbulent boundary layer inception in compressible flows." Journal of Fluid Mechanics 850 (July 12, 2018): 1117–41. http://dx.doi.org/10.1017/jfm.2018.502.
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The behavioural characteristics of thermal boundary layer inception dictate the efficiency of heat exchangers and the operational limits of fluid machinery. The specific time required by the thermal boundary layer to be established is vital to optimize flow control strategies, as well as the thermal management of systems exposed to ephemeral phenomena, typically on the millisecond scale. This paper presents the time characterization of the momentum and thermal boundary layer development in transient turbulent compressible air flows. We present a new framework to perform such estimations based on detailed unsteady Reynolds averaged Navier–Stokes simulations that may be extended to higher fidelity simulations. First of all, the aerodynamic boundary layer initiation is described using adiabatic simulations. Additional numerical calculations were then performed by setting the isothermal wall condition to evaluate the additional time required by the thermal boundary layer to establish after the aerodynamic boundary layer reaches its steady state. Finally, full conjugate simulations were executed to compute the warm up effect of the solid during the blowdown of a hot fluid over a colder metallic test model. The transient performance of the turbulent thermal and momentum boundary layers is quantified through numerical simulations of air blowdown over a flat plate for different mainstream flow conditions. The effects of Reynolds number, free stream velocity, transient duration, test article length and free stream temperature were independently assessed, to then define a mathematical expression of the momentum boundary layer settlement. This paper presents a novel numerical correlation of the additional time required by the thermal boundary layer to be stablished after the settlement of the momentum boundary layer. The time scales of the aerodynamic and thermal boundary layers are presented as a function of relevant non-dimensional numbers, as well as the description of the response of the near wall flow to sudden free stream changes. The characterization of the boundary layer mechanisms discussed in this paper contribute to the establishment of an evidence-based foundation for advances in the field of flow control.
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Eguía Oller, Pablo, José María Alonso Rodríguez, Ángeles Saavedra González, Elena Arce Fariña, and Enrique Granada Álvarez. "Improving transient thermal simulations of single dwellings using interpolated weather data." Energy and Buildings 135 (January 2017): 212–24. http://dx.doi.org/10.1016/j.enbuild.2016.11.030.
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Ivanov, Martin, and Sergey Mijorski. "Assessment of Transient CFD Techniques for Virtual Thermal Manikins’ Breathing Simulations." Environmental Processes 6, no. 1 (January 22, 2019): 241–51. http://dx.doi.org/10.1007/s40710-019-00351-4.
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Hulse, R. J., R. L. Rowley, and W. V. Wilding. "Transient Nonequilibrium Molecular Dynamic Simulations of Thermal Conductivity: 1. Simple Fluids." International Journal of Thermophysics 26, no. 1 (January 2005): 1–12. http://dx.doi.org/10.1007/s10765-005-2349-z.
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Bousquet, Jeremy, Romain Henry, and Armin Seubert. "3-D TRANSIENT COUPLED SIMULATION OF SUPERPHENIX WITH PARCS/ATHLET." EPJ Web of Conferences 247 (2021): 06034. http://dx.doi.org/10.1051/epjconf/202124706034.
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Most safety criteria for Sodium cooled Fast Reactors (SFR) are local core parameters. Thus, application of 3-D neutron kinetic and thermal-hydraulic coupled codes including detailed modelling of core expansion effects is mandatory for best estimate evaluations of safety margins. A recently published benchmark based on measurements performed at the Superph´enix (SPX) reactor offers the opportunity to validate codes and methods for SFR safety assessment. In this paper, the SPX core is modelled in ATHLET and PARCS. Explicit models for axial and radial core expansion effects for 3-D coupled calculations were recently implemented in PARCS. In ATHLET, axial thermal expansion of structures (strongback, vessel, control rod drive line) influencing the relative position of the control rod in the active core is modelled. The newly implemented models are tested on a transient initiated by a reactivity insertion of -50 pcm. A point kinetic simulation is also performed to compare with the 3D solution. Both ATHLET-point kinetic model and ATHLET-PARCS simulations deliver similar power responses during the transient but with an offset. By analysing the different feedbacks in the point kinetic model, it can be concluded that models of expansion of the different structures are well implemented. In the future further analysis of different transients of the benchmark are planned.
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Wang, Rui, Dong Feng Li, Xin Li Han, and Jianxun Zhang. "Experimental and Numerical Study of Transient Distortion in Titanium Alloy Tig Welding." Applied Mechanics and Materials 137 (October 2011): 403–7. http://dx.doi.org/10.4028/www.scientific.net/amm.137.403.
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In this paper, the convex distortion and transient distortion characteristics of TIG welding for a titanium alloy with finite dimensional thin plate were investigated experimentally and numerically. A three dimensional thermal-mechanical finite element method (FEM) was adopted to predict the characteristics of Transient distortion by taking the initial shape, gravity loading and restriction conditions into account. The simulation results were validated by the experimental results. The results show that the numerical simulations could provide accurate prediction on the Transient temperature and distortion processing. The temperature gradient through thickness, the dimension of plate and the clamping were main factors governing the distortion during welding.
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Noetzli, J., and S. Gruber. "Transient thermal effects in Alpine permafrost." Cryosphere Discussions 2, no. 2 (April 2, 2008): 185–224. http://dx.doi.org/10.5194/tcd-2-185-2008.
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Abstract. In high mountain areas, permafrost is important because it influences natural hazards and construction practices, and because it is an indicator of climate change. The modeling of its distribution and evolution over time is complicated by steep and complex topography, highly variable conditions at and below the surface, and varying climatic conditions. This paper presents a systematic investigation of effects of climate variability and topography that are important for subsurface temperatures in Alpine permafrost areas. The effects of both past and projected future ground surface temperature variations on the thermal state of Alpine permafrost are studied based on numerical experimentation with simplified mountain topography. For this purpose, we use a surface energy balance model together with a subsurface heat conduction scheme. The past climate variations that essentially influence the present-day permafrost temperatures at depth are the last glacial period and the major fluctuations in the past millennium. The influence of projected future warming was assessed to cause even larger transient effects in the subsurface thermal field because warming occurs on shorter time scales. Results further demonstrate the accelerating influence of multi-lateral warming in Alpine topography for a temperature signal entering the subsurface. The effects of thermal properties, porosity, and freezing characteristics were examined in sensitivity studies. A considerable influence of latent heat due to water in low-porosity bedrock was only shown for simulations over shorter time periods (i.e., decades to centuries). Finally, as an example of a real and complex topography, the modeled transient three-dimensional temperature distribution in the Matterhorn (Switzerland) is given for today and in 200 years.
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Singh, Vir, Masataka Tanaka, and Morinobu Endo. "Element free Galerkin method for transient thermal analysis of carbon nanotube composites." Thermal Science 12, no. 2 (2008): 39–48. http://dx.doi.org/10.2298/tsci0802039s.
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This paper deals with the transient thermal analysis of carbon nanotube composites via meshless element free Galerkin method. A three-dimensional representative volume element containing single nanotube has been taken as model for these simulations. Essential boundary conditions have been enforced via penalty approach. Simulations using continuum mechanics have been carried out for two different values of nanotube length. Backward difference and Galerkin approaches have been utilized for time approximation, and the results obtained by backward difference method are compared with those obtained by Galerkin approach. .
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Wüest, Thomas, Philipp Schuetz, and Andreas Luible. "Outdoor Test Cell Modelling with Modelica." Buildings 9, no. 10 (September 25, 2019): 209. http://dx.doi.org/10.3390/buildings9100209.
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The experimental setup implements a simplified PASSYS test cell construction, which is combined with a detailed simulation to reduce measurement effort. To analyze the cell’s dynamic behavior, the test cell was closely monitored with thermal sensors, and different static and dynamic heating modes were applied during a three-week calibration period. Co-heating tests were performed for steady-state measurements and cyclic heating periods account for the transient behavior of the test cell. The cells response was compared to the results of transient simulations with the software packet Modelica. The equation based Modelica framework allowed a detailed transient thermal simulation of the test cell’s dynamic to be set up that shows close agreement with the measurements. In addition, the flexibility of Modelica allowed unforeseen events affecting the experimental setup to be replicated, thereby ensuring an uninterrupted heat flow history of all surfaces. More than 96% of the predicted air temperatures (1 min resolution) match the experimental values within an error band of ±1.5 K, and 90% of all predictions are within ±1.0 K.
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Noetzli, J., and S. Gruber. "Transient thermal effects in Alpine permafrost." Cryosphere 3, no. 1 (April 27, 2009): 85–99. http://dx.doi.org/10.5194/tc-3-85-2009.
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Abstract. In high mountain areas, permafrost is important because it influences the occurrence of natural hazards, because it has to be considered in construction practices, and because it is sensitive to climate change. The assessment of its distribution and evolution is challenging because of highly variable conditions at and below the surface, steep topography and varying climatic conditions. This paper presents a systematic investigation of effects of topography and climate variability that are important for subsurface temperatures in Alpine bedrock permafrost. We studied the effects of both, past and projected future ground surface temperature variations on the basis of numerical experimentation with simplified mountain topography in order to demonstrate the principal effects. The modeling approach applied combines a distributed surface energy balance model and a three-dimensional subsurface heat conduction scheme. Results show that the past climate variations that essentially influence present-day permafrost temperatures at depth of the idealized mountains are the last glacial period and the major fluctuations in the past millennium. Transient effects from projected future warming, however, are likely larger than those from past climate conditions because larger temperature changes at the surface occur in shorter time periods. We further demonstrate the accelerating influence of multi-lateral warming in steep and complex topography for a temperature signal entering the subsurface as compared to the situation in flat areas. The effects of varying and uncertain material properties (i.e., thermal properties, porosity, and freezing characteristics) on the subsurface temperature field were examined in sensitivity studies. A considerable influence of latent heat due to water in low-porosity bedrock was only shown for simulations over time periods of decades to centuries. At the end, the model was applied to the topographic setting of the Matterhorn (Switzerland). Results from idealized geometries are compared to this first example of real topography, and possibilities as well as limitations of the model application are discussed.
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Hribernik, Ales, and John J. Moskwa. "Transient Response of a Cross-Flow Charge Air Intercooler and Its Influence on Engine Operation." Journal of Dynamic Systems, Measurement, and Control 122, no. 3 (June 16, 1998): 483–89. http://dx.doi.org/10.1115/1.1286683.
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To examine the influence of intercooler thermal inertia on transient engine operation, a 2D model of an air-to-air, cross-flow heat exchanger has been developed. Finned passages of heat exchanger core have been subdivided into separate channels of charge and cooling air, respectively. A two-step Lax-Wendroff differential method has been used to solve one-dimensional, nonhomentropic, unsteady, compressible fluid flow in each channel. Simultaneously, the Saul’yev explicit method has been applied to compute the 2D temperature distribution along the dividing plate. The Wieting correlation has been used to compute the local convection heat transfer coefficient and friction factor. The model has been verified against steady-state experimental data and then incorporated into an engine cycle simulation program based on “Filling-Emptying” method. Two engine transients have been simulated; the acceleration of the engine from idle to rated engine speed at constant load, and deceleration from rated power to rated torque by increasing the load torque. The first example shows the warming up of the intercooler, while in the second example intercooler temperatures are decreasing. The results have been compared with the predictions of an additional set of simulations, where the NTU-effectiveness method has been used to simulate the intercooler, and the thermal inertia of intercooler has been neglected. The results of both sets of simulations are discussed in the paper. [S0022-0434(00)02003-7]
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Horr, Amir M. "Computational Evolving Technique for Casting Process of Alloys." Mathematical Problems in Engineering 2019 (May 8, 2019): 1–15. http://dx.doi.org/10.1155/2019/6164092.
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The challenging task of bringing together the advanced computational models (with high accuracy) with reasonable computational time for the practical simulation of industrial process applications has promoted the introduction of innovative numerical methods in recent decades. The time and efforts associated with the accurate numerical simulations of manufacturing processes and the sophisticated multiphysical and multiscale nature of these processes have historically been challenging for mainstream industrial numerical tools. In particular, the numerical simulations of industrial continuous and semicontinuous casting processes for light metal alloys have broadly been reinvigorated to investigate the optimization of casting processes. The development of advanced numerical techniques (e.g., multiscale/physical, finite zoning, and evolving domain techniques) for industrial process simulations including the transient melt flow, heat transfer, and evolution of stress/strain and damage during continuous casting processes have endeavored many new opportunities. However, smarter and broader improvements are needed to capture the underlying physical/chemical phenomena including multiscale/physical transient fluid-thermal-mechanical coupling and dynamic heat-transfer changes during these processes. Within this framework, the cooling system including its fluid flow and its characteristic heat transfer has to be modelled. In the research work herein, numerical studies of a novel transient evolving technique including the thermal-mechanical phenomena and Heat Transfer Coefficient (HTC) estimation using empirical and reverse analyses are presented. The phase change modeling during casting process including liquid/solid interface and also the implementation of dynamic HTC curves are also considered. One of the main contributions of this paper is to show the applicability and reliability of the newly developed evolving numerical simulation approach for in-depth investigations of continuous casting processes.
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Hung, Chin Yuan, Yunn Lin Hwang, Wei Hsin Gau, and Kun Nan Chen. "Vibrothermographical Simulation of Cracked Structures." Key Engineering Materials 823 (September 2019): 97–104. http://dx.doi.org/10.4028/www.scientific.net/kem.823.97.
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This research performs finite element simulations of cracked structures undergoing the vibrothermography process, which is an experimental technique gaining popularity for structural damage identification. In vibrothermography, a vibration shaker is used to excite the test structure. If the structure has cracks or defects, frictional heat will be generated at those cracks and thermal images can be recorded by an infrared camera. The vibrothermographical simulation includes modal analysis, transient vibration and transient thermal analysis. Two simulated examples are presented in this work: the first one is an aluminum-alloy plate with a hairline crack; the second example is a brake rotor with a hairline crack on one of the bolt-hole surfaces. Although higher modes are usually more difficult to excite, they may be used in vibrothermography to detect structural cracks more efficiently.
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Shen, Xiaobin, Huanfa Wang, Guiping Lin, Xueqin Bu, and Dongsheng Wen. "Unsteady simulation of aircraft electro-thermal deicing process with temperature-based method." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 2 (August 2, 2019): 388–400. http://dx.doi.org/10.1177/0954410019866066.
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Considering the mass and energy sources carried by the accumulated ice layer, an unsteady heat and mass transfer model of the runback water film on the deicing surface is established to simulate aircraft electro-thermal deicing process. With the extension of the freezing coefficient to the transient calculation, the coupled heat transfer of the runback water and the solid skin is solved at each time step by a temperature-based method. Unsteady numerical simulation is carried out for the electro-thermal deicing system of a NACA 0012 airfoil. The temperature variations with time are in acceptable agreement with the literature data, and the unsteady temperature-based deicing model is verified. The calculation results of temperature, runback water flux and ice thickness on the deicing surface are analyzed at different time points, and it is shown that the unsteady electro-thermal deicing model can capture the main features of the icing, ice melting and re-freezing processes in the transient deicing simulations.
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Królikowski, Igor P., and Jerzy Cetnar. "Neutronic and thermal-hydraulic coupling for 3D reactor core modeling combining MCB and fluent." Nukleonika 60, no. 3 (September 1, 2015): 531–36. http://dx.doi.org/10.1515/nuka-2015-0097.
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Abstract Three-dimensional simulations of neutronics and thermal hydraulics of nuclear reactors are a tool used to design nuclear reactors. The coupling of MCB and FLUENT is presented, MCB allows to simulate neutronics, whereas FLUENT is computational fluid dynamics (CFD) code. The main purpose of the coupling is to exchange data such as temperature and power profile between both codes. Temperature required as an input parameter for neutronics is significant since cross sections of nuclear reactions depend on temperature. Temperature may be calculated in thermal hydraulics, but this analysis needs as an input the power profile, which is a result from neutronic simulations. Exchange of data between both analyses is required to solve this problem. The coupling is a better solution compared to the assumption of estimated values of the temperatures or the power profiles; therefore the coupled analysis was created. This analysis includes single transient neutronic simulation and several steady-state thermal simulations. The power profile is generated in defined points in time during the neutronic simulation for the thermal analysis to calculate temperature. The coupled simulation gives information about thermal behavior of the reactor, nuclear reactions in the core, and the fuel evolution in time. Results show that there is strong influence of neutronics on thermal hydraulics. This impact is stronger than the impact of thermal hydraulics on neutronics. Influence of the coupling on temperature and neutron multiplication factor is presented. The analysis has been performed for the ELECTRA reactor, which is lead-cooled fast reactor concept, where the coolant fl ow is generated only by natural convection
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Zaversky, Fritz, Javier García-Barberena, Marcelino Sánchez, and David Astrain. "Transient molten salt two-tank thermal storage modeling for CSP performance simulations." Solar Energy 93 (July 2013): 294–311. http://dx.doi.org/10.1016/j.solener.2013.02.034.
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Maier, W. "Erwärmung von Kugelgewindetrieben*/Heating of ball screws - Time- and position-dependent heat sources in thermal simulations and experiments." wt Werkstattstechnik online 105, no. 07-08 (2015): 475–81. http://dx.doi.org/10.37544/1436-4980-2015-07-08-33.
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In diesem Fachaufsatz wird die Entwicklung eines thermischen „Matlab Simscape“-Modells vorgestellt. Das geometrisch und zeitlich thermisch transiente Modell „SimTherm“ erlaubt die Berechnung der Erwärmung und Ausdehnung eines Kugelgewindetriebs. Das Modell wird anhand experimenteller Untersuchungen bezüglich der Temperaturverteilung validiert. Die Temperaturen der Kugelgewindetrieb-Spindel werden hierbei ortsvariabel mittels eines Infrarot (IR)-Sensors lokal auf der Spindeloberfläche ermittelt. This paper presents the development of a thermal “Matlab Simscape“ model. The geometrically and timewise thermal-transient model called “SimTherm“ makes it possible to calculate the temperature and the expansion of ball screws. The model is validated with experimental temperature tests. The temperature of the ball screw spindle is established locally on the spindle surface by using an infrared sensor.
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Naik, Korra Nanda, K. R. Balasubramanian, and M. Vasudevan. "Finite Element Simulation of A-TIG Welding of Duplex Stainless Steel 2205 Using SYSWELD." Applied Mechanics and Materials 592-594 (July 2014): 374–79. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.374.
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Bead on plate activated tungsten inert gas (A-TIG) welding of duplex stainless steel (DSS) 2205 was performed to determine the thermal history, temperature distribution and the weld bead geometry. Finite element (FE) simulations were carried out using the software, SYSWELD considering the temperature dependent thermal and mechanical properties of the base material. A 3D double ellipsoidal heat source was employed for the non-linear thermal analysis. The transient temperature distribution, weld bead profile, weld bead dimensions, depth of penetration and bead width were calculated by FE simulation. The simulated weld bead profile was compared with the experimentally measured profile and found to be in agreement.
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Boucheffa, Noureddine, Elhadj Abdellah, and Redha Rebhi. "Two dimensional plasma thermal jet simulations with substrate interaction." Thermal Science, no. 00 (2020): 212. http://dx.doi.org/10.2298/tsci190722212b.
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This paper presents plasma thermal jet simulations with substrate interaction. In this work, two dimensional plasma thermal jet simulations will be presented using the ANSYS-CFX code with taking into account the interaction fluid-substrate during thermal spraying. Two models of turbulence are used such as the shear stress transport K-? (SST- K-?) and Re-Normalization Group (RNG- K-?). The governing parameters of the problem under study are the plasma gas power, the nozzle exit temperature and velocity profiles, the plasma jet temperature and velocity fields and the substrate temperature. The experimental and numerical results are presented in order to carry out a comparison between these results. Moreover, transient simulations will be also treated for different x-positions and different values of time. The distribution of temperature of the substrate will be also presented.
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Zhang, Bo Yi, and Wei Qiang Liu. "Thermal-Structure Coupling Numerical Simulation of a Special-Type Plug Nozzle." Advanced Materials Research 217-218 (March 2011): 1510–15. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.1510.
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Two-dimensional transient heat transfer model of the plug of regenerative cooling plug nozzle is built. Based on the convective heat-transfer coefficient and the radiation heat flux obtained using analytic method and axisymmetric unstructured Delaunay grid applied to mesh the simplified physical model, numerical simulations of transient temperature field and thermal distortion are carried out by finite element method combined with thermal-structure coupling theory. Not only the results of numerical calculation under working conditions with and without regenerative cooling, but the results under low and high working conditions are compared. The results shows that thermal distortion can be reduced effectively when regenerative cooling method is adopted in the throat and combustion chamber that have the most serious thermal condition.
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Avagianos, Ioannis, Dimitrios Rakopoulos, Sotirios Karellas, and Emmanouil Kakaras. "Review of Process Modeling of Solid-Fuel Thermal Power Plants for Flexible and Off-Design Operation." Energies 13, no. 24 (December 14, 2020): 6587. http://dx.doi.org/10.3390/en13246587.
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Since the widespread deployment of non-dispatchable, intermittent, and highly variable power production from renewable energy sources (RES), the demand for flexible power production has been steadily growing. As new-built dispatchable power plants have not been very quickly adapted to the emerging flexible operation, this task has been addressed by existing plants as well. Existing solid-fuel thermal power plants have undergone an extensive study to increase their flexible operation. Thermodynamic process-modeling tools have been extensively used for plant modeling. Steady- and transient-state simulations have been performed under various operating regimes, supplying valuable results for efficient power-plant operation. Flexibility aspects regarding low-load operation and steady operational conditions are mostly investigated with steady-state simulations. Flexibility aspects related to variation over time such as ramping rates are investigated with transient simulations. The off-design operation is mainly attributed to the existing fleet of power plants, struggling to balance between their former operational schemes as base and/or medium-load plants. However, off-design operation is also considered for new plants in the design phase and is included as a simulation aspect. Process modeling turns out to be a proven tool for calculating plant flexibility and predicting extreme operating conditions, defining further steps for a new operational scheme, drafting accident mitigation control procedures or, furthermore, provisioning more complex and cross-field future tasks. A review of the off-design aspect as a simulation approach is undertaken and presented in this work. Finally, challenges and future perspectives for this aspect of solid-fuel thermal power plants are discussed.
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Horka, Lucie, and Jiri Hirs. "Transient simulation study of floor heating systems." International Review of Applied Sciences and Engineering 10, no. 1 (June 2019): 35–41. http://dx.doi.org/10.1556/1848.2019.0006.
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This case study is aimed at transient simulation of floor heating systems. There is comparison of surface floor temperatures and heat fluxes changes of different systems over time. The first studied system is a dry floor heating system which consists of system boards made from insulation material, spreader plates, and it is covered by cement fiber boards. The second examined system is heavy wet concrete floor heating system whose heating power is set identically as heating power of dry floor heating system. Mean temperature of heating water is investigated. All simulations, both time steady-state and transient, are performed in software CalA. Reduction of duration and computational performance of simulation is achieved by creation of a surrogate model. The surrogate model evinces identical surface temperatures and heat fluxes. Total number of computational grid is reduced and therefore lower number of equations is solved. Results show that dry floor heating system has faster response than concreate floor heating system. It is caused by lower weight and lower thermal capacity of this system.
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Azzam, H. "Mathematical networks for thermal transient and non-transient progressive fatigue of engine components." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 212, no. 2 (February 1, 1998): 125–36. http://dx.doi.org/10.1243/0954410981532199.
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Engine components can experience varying centrifugal loads, gas loads, oxidation, micro- structure transformation at high temperatures and stresses induced by temperature gradients. The life consumption of hot engine components depends not only on these factors but also on the time spent at constant-amplitude loads. The damage mechanism of engine components is therefore complex and requires formidable models. These models are not suitable for fatigue management or on-board systems because of their high computational costs. There is a need for efficient simulations that can accurately portray this complex damage mechanism and, at the same time, can be embedded in fatigue management and on-board systems. Mathematical networks were developed to fulfil this need and successfully synthesized the fatigue damage of aircraft structural components from flight parameters. In this paper, the feasibility of training the mathematical networks to synthesize fatigue of engine components is demonstrated. The mathematical attributes of the networks were based on information supplied by Rolls-Royce. The networks’ training mechanism was targeted at the minimization of errors in synthesized accumulative damage values. The mathematical networks synthesized the accumulative fatigue damage of three engine components successfully. One component was subject to non-thermal transient stresses and two components were subject to thermal transient stresses.
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Franchetta, M., K. O. Suen, and T. G. Bancroft. "Pseudo-transient computational fluid dynamics analysis of an underbonnet compartment during thermal soak." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 221, no. 10 (October 1, 2007): 1209–20. http://dx.doi.org/10.1243/09544070jauto555.
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Underbonnet simulations are proving to be crucially important within a vehicle development programme, reducing test work and time-to-market. While computational fluid dynamics (CFD) simulations of steady forced flows have been demonstrated to be reliable, studies of transient convective flows in engine compartments are not yet carried out owing to high computing demands and lack of validated work. The present work assesses the practical feasibility of applying the CFD tool at the initial stage of a vehicle development programme for investigating the thermally driven flow in an engine bay under thermal soak. A computation procedure that enables pseudo time-marching CFD simulations to be performed with significantly reduced central processing unit (CPU) time usage is proposed. The methodology was initially tested on simple geometries and then implemented for investigating a simplified half-scale underbonnet compartment. The numerical results are compared with experimental data taken with thermocouples and with particle image velocimetry (PIV). The novel computation methodology is successful in efficiently providing detailed and time-accurate time-dependent thermal and flow predictions. Its application will extend the use of the CFD tool for transient investigations, enabling improvements to the component packaging of engine bays and the refinement of thermal management strategies with reduced need for in-territory testing.
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Łuczyński, Piotr, Matthias Giesen, Thomas-Sebastian Gier, and Manfred Wirsum. "Uncoupled CFD-FEA Methods for the Thermo-Structural Analysis of Turbochargers." International Journal of Turbomachinery, Propulsion and Power 4, no. 4 (November 28, 2019): 39. http://dx.doi.org/10.3390/ijtpp4040039.
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In turbocharger design, the accurate determination of thermally induced stresses is of particular importance for life cycle predictions. An accurate, transient, thermal finite element analysis (FEA) of turbocharger components requires transient conjugate heat transfer (CHT) analysis. However, due to the vastly different timescales of the heat transfer mechanisms in fluid and in solid states, unsteady CHT simulations are burdened by high computational costs. Hence, for design iterations, uncoupled CFD and FEA approaches are needed. The quality of the uncoupled thermal analysis depends on the local heat transfer coefficients (HTC) and reference fluid temperatures. In this paper, multiple CFD-FEA methods known from literature are implemented in a numerical model of a turbocharger. In order to describe the heat transfer and thermal boundary layer of the fluid, different definitions of heat transfer coefficients and reference fluid temperatures are investigated with regard to calculation time and accuracy. For the transient simulation of a long heating process, the combination of the CFD-FEA methods with the interpolation FEA approach is examined. Additionally, a structural-mechanical analysis is conducted. The results of the developed methods are evaluated against experimental data and the results of the extensive unsteady CHT numerical method.
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Laurence, S. J., S. Karl, J. Martinez Schramm, and K. Hannemann. "Transient fluid-combustion phenomena in a model scramjet." Journal of Fluid Mechanics 722 (March 28, 2013): 85–120. http://dx.doi.org/10.1017/jfm.2013.56.
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AbstractAn experimental and numerical investigation of the unsteady phenomena induced in a hydrogen-fuelled scramjet combustor under high-equivalence-ratio conditions is carried out, focusing on the processes leading up to unstart. The configuration for the study is the fuelled flow path of the HyShot II flight experiment. Experiments are performed in the HEG reflected-shock wind tunnel, and results are compared with those obtained from unsteady numerical simulations. High-speed schlieren and OH∗ chemiluminescence visualization, together with time-resolved surface pressure measurements, allow links to be drawn between the experimentally observed flow and combustion features. The transient flow structures signalling the onset of unstart are observed to take the form of an upstream-propagating shock train. Both the speed of propagation and the downstream location at which the shock train originates depend strongly on the equivalence ratio. The physical nature of the incipient shock system, however, appears to be similar for different equivalence ratios. Both experiments and computations indicate that the primary mechanism responsible for the transient behaviour is thermal choking, though localized boundary-layer separation is observed to accompany the shock system as it moves upstream. In the numerical simulations, the global choking behaviour is dictated by the limited region of maximum heat release around the shear layer between the injected hydrogen and the incoming air flow. This leads to the idea of ‘local’ thermal choking and results in a lower choking limit than is predicted by a simple integral analysis. Such localized choking makes it possible for new quasi-steady flow topologies to arise, and these are observed in both experiments and simulation. Finally, a quasi-unsteady one-dimensional analytical model is proposed to explain elements of the shock-propagation behaviour.
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Giuntini, Sabrina, Antonio Andreini, Bruno Facchini, Marco Mantero, Marco Pirotta, and Sven Olmes. "Transient 2D FEM-fluid network coupling for thermo-mechanical whole gas turbine engine simulations: modelling features and applications." E3S Web of Conferences 197 (2020): 10012. http://dx.doi.org/10.1051/e3sconf/202019710012.
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In order to control the thermo-mechanical stresses that large heavy-duty power generation turbines have to face nowadays in their frequent operational transients, the analysis of the heat transfer between main flow, secondary air systems and structural components has to consider multi-physics coupled interactions, and has to be carried out with a whole engine modelling approach, simulating the entire machine in the real operating conditions. This is fundamental to guarantee a reliable assessment of life timing consumption and optimize clearances and temperature picks, through an efficient secondary air system design. It is here proposed a comprehensive description of modelling features and assumptions needed for the transient thermo-mechanical characterization of the whole engine through the application of a FEM-fluid network coupling methodology developed in collaboration with Ansaldo Energia and based on the open source code CalculiX®. In the present work the transient thermal modelling capability of the procedure will be verified through its application to a real whole engine geometry under a realistic transient cycle, comparing results with those of a reference FEM code.
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XU, FENG, JOHN C. PATTERSON, and CHENGWANG LEI. "Transient natural convection flows around a thin fin on the sidewall of a differentially heated cavity." Journal of Fluid Mechanics 639 (October 7, 2009): 261–90. http://dx.doi.org/10.1017/s0022112009990991.
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Transient natural convection flows around a thin fin on the sidewall of a differentially heated cavity, which includes a lower intrusion under the fin, a starting plume bypassing the fin and a thermal flow entrained into the vertical thermal boundary layer downstream of the fin in a typical case, are investigated using a scaling analysis and direct numerical simulations. The obtained scaling relations show that the thickness and velocity of the transient natural convection flows around the fin are determined by different dynamic and energy balances, which can be either a buoyancy-viscous balance or a buoyancy-inertial balance, depending on the Rayleigh number, the Prandtl number and the fin length. A time scale of the transition from a buoyancy-viscous flow regime to a buoyancy-inertial flow regime is obtained. The major scaling relations quantifying the transient natural convection flows are also validated by direct numerical simulations. In general, there is a good agreement between the scaling predictions and the corresponding numerical results.
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Pascal, V., Y. Gorsse, N. Alpy, K. Ammar, M. Anderhuber, AM Baudron, G. Campioni, et al. "MULTIPHYSICS MODELISATION OF AN UNPROTECTED LOSS OF FLOW TRANSIENT IN A SODIUM COOLED FAST REACTORS USING A NEUTRONIC-THERMAL-HYDRAULIC COUPLING SCHEME." EPJ Web of Conferences 247 (2021): 07001. http://dx.doi.org/10.1051/epjconf/202124707001.
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Sodium cooled fast neutron reactors (SFR) are one of the selected reactor concepts in the framework of the Generation IV International Forum. In this concept, unprotected loss of cooling flow transients (ULOF), for which the non-triggering of backup systems is postulated, are regarded as potential initiators of core melting accidents. During an ULOF transient, spatial distributions of fuel, structure and sodium temperatures are affected by the core cooling flow decrease, which will modify the spatial and energy distribution of neutron in the core due to the spatial competition of neutron feedback effects. As no backup systems are triggered, sodium may reach its boiling temperature at some point, leading to local sodium density variations and making the transient fluctuate in a two-phase flow physics where thermal-hydraulics and neutronics may interact with each other. The transient phenomenology involves several physic disciplines at different time and spatial scales, such as core neutronics, coolant thermal-hydraulics and fuel thermo-mechanics. This paper presents the results of thermal-hydraulic/neutronic coupled simulations of an ULOF transient on the SFR project ASTRID. These coupled calculations are based on the supervisor platform SALOME to link the neutron code APOLLO3® to the system thermal-hydraulic code CATHARE3. The physical approach used by the coupling to describe the neutron kinetic is a quasi-static adiabatic one, updating the normalized spatial power distribution periodically by performing static neutron calculations, while a point kinetic model associated to a neutron feedback model calculates the power amplitude variations.
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Kumar, Chandan, and Nilamber Kumar Singh. "Responses of Aluminium Alloy Pistons under Mechanical and Thermal Loads." Materials Science Forum 969 (August 2019): 231–36. http://dx.doi.org/10.4028/www.scientific.net/msf.969.231.
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A comparative study of three different aluminium alloys, Al2618, Al4032 and Al6061 made internal combustion engine pistons is done on their responses under mechanical and thermal loads using finite element methods. In this study, a 3D solid model of piston is created in CATIA and the simulations of the static structural analysis, steady-state thermal analysis and transient thermal analysis are carried out in ANSYS. Stress and temperature distributions on critical areas of piston are pointed out for appropriate modification in piston design. The temperature and heat flux variations with time are presented in transient thermal analysis. Taguchi method and topological optimization are applied to optimize the process parameters and to select the appropriate material for the piston.
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Asifa, Khurram, Hong Li, Li Li, and Shehzad Khurram. "Parametric Study of Welding Temperature Distribution in T-Joint Fillet Weld Using FEM." Advanced Materials Research 328-330 (September 2011): 492–96. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.492.
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This paper presents FE simulation of Arc welding process using nonlinear transient thermal analysis to study the effect of process parameters on temperature distributions in T-joint fillet welds. An APDL (ANSYS Parametric Design Language) program is developed to define moving surface heat source model with Gaussian distribution into simulations by using commercially available FE code ANSYS. The transient temperature distribution in fillet weld during welding process are predicted and subsequently validated with published experimental results. Influence of heat energy input, electrode angle, welding speed and plate thickness on temperature distribution was further explored. The present work provides a basis for prediction of welding residual stresses and distortions in fillet joints.
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Franz, Daniel, Maximilian Schneider, Michael Richter, and Stephan Rinderknecht. "Thermal Behavior of a Magnetically Levitated Spindle for Fatigue Testing of Fiber Reinforced Plastic." Actuators 8, no. 2 (May 3, 2019): 37. http://dx.doi.org/10.3390/act8020037.
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This article discusses the critical thermal behavior of a magnetically levitated spindle for fatigue testing of cylinders made of fiber reinforced plastic. These cylinders represent the outer-rotor of a kinetic energy storage. The system operates under vacuum conditions. Hence, even small power losses in the rotor can lead to a high rotor temperature. To find the most effective way to keep the rotor temperature under a critical limit in the existing system, first, transient electromagnetic finite element simulations are evaluated for the active magnetic bearings and the electric machine. Using these simulations, the power losses of the active components in the rotor can be derived. Second, a finite element simulation characterizes the thermal behavior of the rotor. Using the power losses calculated in the electromagnetic simulation, the thermal simulation provides the temperature of the rotor. These results are compared with measurements from an experimental spindle. One effective way to reduce rotational losses without major changes in the hardware is to reduce the bias current of the magnetic bearings. Since this also changes the characteristics of the magnetic bearings, the dynamic behavior of the rotor is also considered.
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Fan, Youping, Peng Zhang, Ben Shang, Dianlang Wang, Wen’an Li, Dongjian Zhuang, Zihan Chen, Zhaoyi Zhang, and Wu Wen. "Thermal Characteristic Simulation Study of Multicolumn Parallel Zinc Oxide Arresters under Extreme Operating Conditions." Electronics 12, no. 1 (December 26, 2022): 100. http://dx.doi.org/10.3390/electronics12010100.
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The arrester plays an important role in the protection of the DC transmission system, and its thermal characteristics under different operating conditions greatly affect its performance. To study the thermal characteristics of multicolumn parallel arresters under extreme operating conditions in a DC system, considering the influence of SF6 fluid, the structural parameters of the ±500 kV Niu Cong DC transmission project were applied for this research. Firstly, a 3D model of the four-column parallel zinc oxide arrester installed on the neutral bus of the ±500 kV Niu Cong DC transmission project was built in ANSYS to analyze its thermal conduction. Then, the electromagnetic transient model of the Niu Cong DC transmission system was established in PSCAD to study the withstood energy of a four-column parallel zinc oxide arrester under 22 typical fault conditions in three operation modes. Based on the extreme operating conditions obtained, simulations of steady-state and transient thermal characteristics were performed considering the influence of SF6 fluid flow on the heat dissipation of the arrester. Finally, the field-test temperature test on the four-column parallel zinc oxide arrester was carried out to validate the effectiveness of the proposed simulation model and calculation method, with simulation data matching well with the field-test data. The results also conclude the thermal characteristics findings to reveal the thermal conduction of multicolumn arresters under extreme operating conditions.
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Nagy, Balázs, and Elek Tóth. "Finite Element Analysis of Composite Ceramic-Concrete Slab Constructions Exposed to Fire." Applied Mechanics and Materials 861 (December 2016): 88–95. http://dx.doi.org/10.4028/www.scientific.net/amm.861.88.
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In this research, conjugated thermal and fluid dynamics simulations are presented on a modern hollow clay slab blocks filled pre-stressed reinforced concrete beam slab construction. The simulation parameters were set from Eurocode standards and calibrated using data from standardized fire tests of the same slab construction. We evaluated the temperature distributions of the slabs under transient conditions against standard fire load. Knowing the temperature distribution against time at certain points of the structure, the loss of load bearing capacity of the structure is definable at elevated temperatures. The results demonstrated that we could pre-establish the thermal behavior of complex composite structures exposed to fire using thermal and CFD simulation tools. Our results and method of fire resistance tests can contribute to fire safety planning of buildings.
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Nyberg, Karen L., Kenneth R. Diller, and Eugene H. Wissler. "Model of Human/Liquid Cooling Garment Interaction for Space Suit Automatic Thermal Control." Journal of Biomechanical Engineering 123, no. 1 (October 13, 2000): 114–20. http://dx.doi.org/10.1115/1.1336147.
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The Wissler human thermoregulation model was augmented to incorporate simulation of a space suit thermal control system that includes interaction with a liquid cooled garment (LCG) and ventilation gas flow through the suit. The model was utilized in the design process of an automatic controller intended to maintain thermal neutrality of an exercising subject wearing a liquid cooling garment. An experimental apparatus was designed and built to test the efficacy of specific physiological state measurements to provide feedback data for input to the automatic control algorithm. Control of the coolant inlet temperature to the LCG was based on evaluation of transient physiological parameters that describe the thermal state of the subject, including metabolic rate, skin temperatures, and core temperature. Experimental evaluation of the control algorithm function was accomplished in an environmental chamber under conditions that simulated the thermal environment of a space suit and transient metabolic work loads typical of astronaut extravehicular activity (EVA). The model was also applied to analyze experiments to evaluate performance of the automatic control system in maintaining thermal comfort during extensive transient metabolic profiles for a range of environmental temperatures. Finally, the model was used to predict the efficacy of the LCG thermal controller for providing thermal comfort for a variety of regimens that may be encountered in future space missions. Simulations with the Wissler model accurately predicted the thermal interaction between the subject and LCG for a wide range of metabolic profiles and environmental conditions and matched the function of the automatic temperature controller for inlet cooling water to the LCG.