Transient, Three-Dimensional Numerical Model of a Laser Cutting Process With Phase Change Consideration

2004 ◽  
Author(s):  
Gustavo Gutie´rrez ◽  
Juan Guillermo Araya
Keyword(s):  
Temperature Field ◽  
Laser Beam ◽  
Phase Change ◽  
Numerical Models ◽  
Three Dimensional ◽  
Phase Changes ◽  
Ceramic Surface ◽  
Numerical Predictions ◽  
Physical Shape ◽  
Finite Volume Approach

Phase change problems are encountered in several manufacturing and material processing applications. Such problems are computationally challenging because it is necessary to solve a non-linear heat conduction equation and take into considerations the conditions needed to produce material ablation, varying continuously the heat source position, thermo physical properties and physical shape of the domain. This research presents a numerical simulation of the temperature field and the removed material resulting from the impingement of a moving laser beam on a ceramic surface. A finite volume approach has been developed to predict the temperature field including phase changes generated during the process. The model considers heat losses by convection and radiation due to the high temperatures involved and uses a coordinate system affixed to the workpiece; therefore no quasi-steady conditions are assumed, as in the majority of previous works. Numerical predictions were compared with former three-dimensional numerical models considering a semi-infinite solid and from experimental data found in the literature. This study gives insight into the interactions between the laser beam and a silicon nitride workpiece during the cutting.

scholarly journals Three-Dimensional Temperature Distribution Produced by a Moving Laser Beam

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
R. Uyhan
Keyword(s):  
Temperature Field ◽  
Theoretical Model ◽  
Temperature Distribution ◽  
Laser Beam ◽  
Three Dimensional ◽  
Constant Speed ◽  
Unsteady Temperature ◽  
Unsteady Temperature Field ◽  
Absorbing Layer

An axisymmetric laser beam, moving with constant speed, heats a thin infrared absorbing layer sandwiched between two plastic sheets. We use a simplified theoretical model to study the three-dimensional unsteady temperature field produced by the moving laser beam.

scholarly journals Mine Backfilling in the Permafrost, Part I: Numerical Prediction of Thermal Curing Conditions within the Cemented Paste Backfill Matrix

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 165 ◽  
Author(s):  
Fabrice Beya ◽  
Mamert Mbonimpa ◽  
Tikou Belem ◽  
Li Li ◽  
Ugo Marceau ◽  
...  
Keyword(s):  
Temperature Field ◽  
Numerical Models ◽  
Three Dimensional ◽  
Equilibrium Temperature ◽  
Cemented Paste Backfill ◽  
Thermal Curing ◽  
Curing Conditions ◽  
Permafrost Rock ◽  
Thermal Boundary Conditions ◽  
Paste Backfill

The mechanical behavior of cemented paste backfill (CPB) in permafrost regions may depend on the thermal curing conditions. However, few experimental data are available for calibrating and validating numerical models used to predict these conditions. To fill this gap, a three-dimensional (3D) laboratory heat transfer test was conducted on CPB placed in an instrumented barrel and cured under a constant temperature of −11 °C. Results were used to calibrate and validate a numerical model built with COMSOL Multiphysics®. The model was then used to predict the evolution of the temperature field for CPB cured under the thermal boundary conditions for a backfilled mine stope in the permafrost (at −6 °C). Numerical results indicated that the CPB temperature gradually decreased with time such that the entire CPB mass was frozen about five years after stope backfilling. However, the permafrost equilibrium temperature of −6 °C was not reached throughout the entire CPB mass even after 20 years of curing. In addition, the evolution of the temperature field in the permafrost rock showed that the thickness of the thawed portion reached about 1 m within 120 days. Afterwards, the temperature continues to drop over time and the thawed portion of the permafrost refreezes after 365 days.

Modeling of Titanium Oxide Layer Growth Produced by Fiber Laser Beam

2013 ◽  
Vol 336 ◽  
pp. 11-18 ◽  
Author(s):  
Farida Hamadi ◽  
El Hachemi Amara ◽  
Djamila Bennaceur-Doumaz ◽  
R. Boutaka ◽  
H. Kellou ◽  
...  
Keyword(s):  
Temperature Field ◽  
Laser Beam ◽  
Film Growth ◽  
Three Dimensional ◽  
Layer Growth ◽  
Heat Diffusion ◽  
Metallic Surface ◽  
Heat Diffusion Equation ◽  
Computational Procedures ◽  
Volume Method

In this paper, we study the oxidation process during the heating of a titanium metallic surface by a Nd-YAG fiber pulsed laser beam under air environment. For this, we adopted an approach that considers a three-dimensional heat diffusion model coupled with an oxidation parabolic law (oxidation kinetics). The heat diffusion equation solved numerically, gives the temperature field. The oxide film growth is simulated by implementing a dynamic mesh technique. We developed computational procedures UDFs (User Defined Function) running interactively with the Fluent fluid dynamics software [ that implements the finite volume method. These UDFs are developed to insert the oxidation law, the temperature field, the specific boundary conditions and the mesh deformation into the calculation.

Two Numerical Models for Prediction of an Industrial Concasting Process

2003 ◽  
Author(s):  
Frantisek Kavicka ◽  
Josef Stetina ◽  
Karel Stransky ◽  
Jana Dobrovska ◽  
Vera Dobrovska ◽  
...  
Keyword(s):  
Temperature Field ◽  
Numerical Model ◽  
Numerical Models ◽  
Three Dimensional ◽  
Crystallization Rate ◽  
Dendritic Segregation ◽  
Distribution Of Elements ◽  
Technological Impact ◽  
The Mean ◽  
Constituent Elements

This paper introduces the application of two three-dimensional (3D) numerical models of the temperature field of a caster. The first model simulates the temperature field of a caster—either as a whole, or any of its parts. Experimental research and data acquisition take place simultaneously with the numerical computation in order to enhance the numerical model and to perfect it in the course of the process. In order to apply the second original numerical model—a model of dendritic segregation of elements—it is necessary to analyze the heterogeneity of samples of the constituent elements and impurities in characteristic places of the solidifying slab. The samples are taken from places, which provide information on the distribution of elements under both standard and extreme conditions for solidification, where the mean solidification (crystallization) rate is known for points between the solidus and liquidus curves. Using this method, it is possible to forecast the occurrence of the critical points of a slab from the viewpoint of its susceptibility to crack and fissure. Verification of the technological impact of optimization, resulting from both models, is conducted on a real industrial caster.

scholarly journals Investigation of a Temperature Field of the Steel Billet 150x150 mm Continuously Cast

2020 ◽  
Vol 328 ◽  
pp. 03002
Author(s):  
František Kavička ◽  
Jaroslav Katolický ◽  
Josef Štětina ◽  
Tomáš Mauder ◽  
Lubomír Klimeš
Keyword(s):  
Mass Transfer ◽  
Temperature Field ◽  
Numerical Models ◽  
Three Dimensional ◽  
Cast Billet ◽  
Operational Parameters ◽  
Measurement Results ◽  
Simultaneous Heating ◽  
Continuously Cast Billet ◽  
Continuously Cast

The solidification and cooling of a continuously cast billet and the simultaneous heating of the mold is a very complicated problem of three-dimensional (3D) transient heat and mass transfer. The solving of uch a problem is impossible without numerical models of the temperature field of the concasting itself which it is being processed through the concasting machine (caster). The application of the numerical model requires systematic experimentation and measurement of operational parameters on a real caster as well as in the laboratory. The measurement results, especially temperatures, serve not only for the verification of the exactness of the model, but mainly for optimization of the process procedure. The most important part of the investigation is the measurement of the temperatures in the walls of the mold and the surface of the slab in the zones of secondary and tertiary cooling.

Numerical modeling of hybrid laser welding taking into account phase change of material

2017 ◽  
Vol 36 (2) ◽  
pp. 417-426 ◽  
Author(s):  
Ivo Doležel ◽  
Václav Kotlan ◽  
Roman Hamar ◽  
David Pánek
Keyword(s):  
Laser Beam ◽  
Laser Welding ◽  
Phase Change ◽  
3D Model ◽  
Three Dimensional ◽  
Physical Parameters ◽  
Saturation Curve ◽  
Plasma Cloud ◽  
Content Type ◽  
Liquid Phases

Purpose This paper aims to present a three-dimensional (3D) model of hybrid laser welding of a steel plate. Before welding, the plate is pre- and/or post-heated by induction to avoid mechanical stresses in material due to high gradients of temperature. Welding itself is realized by laser beam without welding rod. The model takes into account existence of both solid and liquid phases in the weld. Design/methodology/approach Presented is the complete mathematical model of the above heat treatment process, taking into account all relevant nonlinearities (saturation curve of the processed steel material and temperature dependences of its physical parameters). Its numerical solution is realized by the finite element method. Some important results are compared with experimental data. Findings In comparison with the former model developed by the authors that did not take into account the phase change, the results are more realistic and exhibit a better accordance with measurements. On the other hand, they strongly depend on sufficiently accurate knowledge of material parameters in both solid and liquid levels (that represent the input data). Research limitations/implications The quality of calculated results strongly depends on the material properties and their temperature dependencies. In case of alloys (whose chemical composition may vary in some range), such data are often unavailable and must be estimated on the basis of experiments. Another quantity that has to be calibrated is the time dependence of power delivered by the laser beam, which is due to the production of a plasma cloud above the exposed spot. Practical implications The presented model and methodology of its solution may represent a basis for design of the complete technology of laser welding with induction pre-heating and/or post-heating. Originality/value Fully 3D model of hybrid laser welding (supplemented with pre- and/or post-heating by magnetic induction) taking into account both solid and liquid phases of welded metal and influence of the plasma cloud is presented.

Thermal and Dimensional Process Characteristics in Laser-Aided Rapid Manufacturing

2000 ◽  
Author(s):  
Franz-Josef Kahlen ◽  
Aravinda Kar
Keyword(s):  
Laser Beam ◽  
Three Dimensional ◽  
Emission Spectra ◽  
Phase Changes ◽  
Process Characteristics ◽  
Melt Pool ◽  
Plume Temperature ◽  
Solid Liquid ◽  
Melt Pool Characteristics ◽  
Deposition Height

Abstract Three-dimensional cylindrical and wall-like structures of copper, Ti-6Al-4V, aluminum, and stainless steel 304 were fabricated by melting the powders of these materials with a CO2 laser beam. A vapor-plasma plume is generated at the top of the melt layer. The emission spectra of the plume were recorded using an optical multichannel analyzer, and the plume temperatures are determined to be in the range of 4920 K to 6720 K. A one-dimensional model is developed to calculate the plume temperature, deposition geometry and melt pool characteristics. The model accounts for the transmission of the laser beam through the plume, energy transfer in the molten phase and the phase changes at the solid-liquid and liquid-vapor interfaces. The surface temperature at the molten surface is found to exceed the normal boiling temperature causing the pressure to be higher than one atmospheric pressure. The calculated plume temperatures are in good agreement with the values obtained from the spectral data. Also, the model predictions for remelt layer depth, deposition height and plasma height compare well with experimental data.

scholarly journals Thermal and hydraulic performance analysis of a heat sink with corrugated channels and nanofluids

2020 ◽  
Author(s):  
Benyamin Naranjani ◽  
Ehsan Roohi ◽  
Amin Ebrahimi
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Three Dimensional ◽  
Hydraulic Performance ◽  
Heat Sinks ◽  
Maximum Temperature ◽  
Thermally Induced ◽  
Numerical Predictions ◽  
Overall Performance ◽  
Finite Volume Approach

Abstract Cooling of electronic devices is one of the critical challenges that the electronics industry is facing towards sustainable development. Aiming at lowering the surface temperature of the heat sink to limit thermally induced deformations, corrugated channels and nanofluids are employed to improve the thermal and hydraulic performances of a heat sink. Three-dimensional simulations based on the finite-volume approach are carried out to study conjugated heat transfer in the heat sink. Water-based nanofluids containing $$\hbox {Al}_{2}\hbox {O}_{3}$$ Al 2 O 3 nanoparticles with two different particle sizes (29 nm and 40 nm) and volume fractions less than 4% are employed as the coolant, and their influence on the thermal and hydraulic performance of the heat sink is compared with the base fluid (i.e. water). An empirical model is utilised to approximate the effective transport properties of the nanofluids. Employing corrugated channels instead of straight channels in the heat sink results in an enhancement of 24–36% in the heat transfer performance at the cost of 20–31% increase in the required pumping power leading to an enhancement of 16–24% in the overall performance of the heat sink. Additionally, the numerical predictions indicate that the overall performance of the proposed heat sink design with corrugated channels and water–$$\hbox {Al}_{2}\hbox {O}_{3}$$ Al 2 O 3 nanofluids is 22–40% higher than that of the water-cooled heat sink with straight channels. It is demonstrated that the overall performance of the heat sink cooled with water–$$\hbox {Al}_{2}\hbox {O}_{3}$$ Al 2 O 3 nanofluids increases with reducing the average nanoparticle size. Additionally, the maximum temperature rise in the heat sinks is determined for different thermal loads.

Influence of Metal Substitution on the Pressure-Induced Phase Change in Flexible Zeolitic Imidazolate Frameworks

2018 ◽  
Author(s):  
C. Michael McGuirk ◽  
Tomče Runčevski ◽  
Julia Oktawiec ◽  
Ari Turkiewicz ◽  
mercedes K. taylor ◽  
...  
Keyword(s):  
Phase Change ◽  
Single Crystal ◽  
Gas Adsorption ◽  
High Capacity ◽  
Phase Changes ◽  
Zeolitic Imidazolate Frameworks ◽  
Metal Substitution ◽  
Heat Management ◽  
Metal Organic ◽  
First Time

<p>Metal–organic frameworks that display step-shaped adsorption profiles arising from discrete pressure-induced phase changes are promising materials for applications in both high-capacity gas storage and energy-efficient gas separations. The thorough investigation of such materials through chemical diversification, gas adsorption measurements, and <i>in situ </i>structural characterization is therefore crucial for broadening their utility. We examine a series of isoreticular, flexible zeolitic imidazolate frameworks (ZIFs) of the type M(bim)<sub>2</sub> (SOD; M = Zn<sup> </sup>(ZIF-7), Co (ZIF-9), Cd (CdIF-13); bim<sup>–</sup> = benzimidazolate), and elucidate the effects of metal substitution on the pressure-responsive phase changes and the resulting CO<sub>2</sub> and CH<sub>4</sub> step positions, pre-step uptakes, and step capacities. Using ZIF-7 as a benchmark, we reexamine the poorly understood structural transition responsible for its adsorption steps and, through high-pressure adsorption measurements, verify that it displays a step in its CH<sub>4 </sub>adsorption isotherms. The ZIF-9 material is shown to undergo an analogous phase change, yielding adsorption steps for CO<sub>2</sub> and CH<sub>4</sub> with similar profiles and capacities to ZIF-7, but with shifted threshold pressures. Further, the Cd<sup>2+</sup> analogue CdIF-13 is reported here for the first time, and shown to display adsorption behavior distinct from both ZIF-7 and ZIF-9, with negligible pre-step adsorption, a ~50% increase in CO<sub>2</sub> and CH<sub>4</sub> capacity, and dramatically higher threshold adsorption pressures. Remarkably, a single-crystal-to-single-crystal phase change to a pore-gated phase is also achieved with CdIF-13, providing insight into the phase change that yields step-shaped adsorption in these flexible ZIFs. Finally, we show that the endothermic phase change of these frameworks provides intrinsic heat management during gas adsorption. </p>

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