Numerical investigation of gas-disperse jet flows created by coaxial nozzles during the laser direct material deposition

Ковалев, О. Б.; Kovaleva, I. O.; Smurov, I.

doi:10.1016/j.jmatprotec.2017.05.041

Cited by 66 publications

(26 citation statements)

References 21 publications

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“…Similar observations could appear with Nozzles B and C for very high powder flow rates. Considering this, new simulations were performed with an inelastic rebound on the axis of symmetry of nozzle A with 30% of velocity loss after the impact [20]. Results show a much better agreement with experimental results, even if the stream diameter at the focal plane is still slightly over-estimated by numerical results (Figure 7b).…”

mentioning

confidence: 83%

“…Arrizubieta et al [19] underlined the formation of an asymmetric powder jet for a coaxial nozzle tilt higher than 30 • relative to the vertical axis, which has a significant impact on the direction dependence of the process. The typical patterns of powder density and particle temperature distributions were found to be dependent on the coaxial nozzle type by Kovalev et al [20]. Considering all these works, it can clearly be established that the nozzle design and gas parameters have a strong impact on the powder flow density, speed and trajectory, and hence directly influence the powder stream characteristics and the clad efficiency [21].…”

Section: Experimental Conditionsmentioning

confidence: 94%

“…Collisions between particles were neglected due to their low volume fraction (< 10%) and no heat transfer between gas and particles was considered so that all particles remained solid during their time-of-flight. Finally, inelastic rebounds of particles on the nozzle walls were considered as a 10% loss of the incident particle velocity during rebound [20].…”

Section: Modelling Of the Secondary Particle Phasementioning

confidence: 99%

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Experimental and Numerical Analysis of Gas/Powder Flow for Different LMD Nozzles

Ferreira

Dal

Colin

et al. 2020

Metals

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The Laser Metal Deposition (LMD) process is an additive manufacturing method, which generates 3D structures through the interaction of a laser beam and a gas/powder stream. The stream diameter, surface density and focal plan position affect the size, efficiency and regularity of the deposit tracks. Therefore, a precise knowledge of the gas/powder streams characteristics is essential to control the process and improve its reliability and reproducibly for industrial applications. This paper proposes multiple experimental techniques, such as gas pressure measurement, optical and weighting methods, to analyze the gas and particle velocity, the powder stream diameter, its focal plan position and density. This was carried out for three nozzle designs and multiple gas and powder flow rates conditions. The results reveal that (1) the particle stream follows a Gaussian distribution while the gas velocity field is closer to a top hat one; (2) axial, carrier and shaping gas flow significantly impact the powder stream’s focal plan position; (3) only shaping gas, powder flow rates and nozzle design impact the powder stream diameter. 2D axisymmetric models of the gas and powder streams with RANS turbulent model are then performed on each of the three nozzles and highlight good agreements with experimental results but an over-estimation of the gas velocity by pressure measurements.

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confidence: 83%

Section: Experimental Conditionsmentioning

confidence: 94%

Section: Modelling Of the Secondary Particle Phasementioning

confidence: 99%

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Experimental and Numerical Analysis of Gas/Powder Flow for Different LMD Nozzles

Ferreira

Dal

Colin

et al. 2020

Metals

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“…Numerical and analytical models with varying depths of detail, scopes and assumptions for the mathematical definition of the powder-gas jet forming behind the nozzle tip are described in the literature. In most cases, the powder-gas jet is described numerically with the standard k-ε turbulence model for turbulent two-phase flows [31][32][33][34][35]. The k-ε model is a transport equation for a viscous vortex model in which the turbulent flow is described with the two parameters k for the turbulent kinetic energy and ε for the dissipation rate.…”

Section: Modelling Of the Powder-gas Jet Or Powder Particle Density Dmentioning

confidence: 99%

Statistical/Numerical Model of the Powder-Gas Jet for Extreme High-Speed Laser Material Deposition

et al. 2020

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Extreme high-speed laser material deposition, known by its German acronym EHLA, is a new variant of laser material deposition (LMD) with powdered additives. This variant’s process control is unlike that of LMD, where the powder melts as it contacts the melt pool. In the EHLA process, the laser beam melts the powder above the surface of the substrate to deliver a liquid to the melt pool. At a given intensity distribution in a laser beam, the heating of powder particles in the beam path depends largely on the three-dimensional powder particle density distribution (PDD) and the relative position within the laser beam caustic. As a key element of a comprehensive numerical process model for EHLA, this paper presents a statistical/numerical model of the powder-gas jet, as previously published in Experimentelle und modelltheoretische Untersuchungen zum Extremen Hochgeschwindigkeits-Laserauftragschweißen. The powder-gas jet is characterized experimentally and described with a mathematical model. This serves to map the PDD of the powder-gas flow—and particularly the particle trajectories for different grain fractions—as well as the powder mass flows and carrier and inert gas settings, to a theoretical model. The result is a numerical description of the particle trajectories that takes into account the measured particle size distribution with calculations made on the assumption of a constant particle velocity and linear trajectories of the particles.

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“…Um elevado volume de gás, tanto o de proteção quanto o de transporte, pode resultar em uma menor densidade de pó metálico na poça de fusão, o que diminui a eficiência do processo. A otimização dos parâmetros, referente ao fluxo de gás de proteção e ao fluxo de gás de transporte, possui uma importante influência na diminuição da quantidade de porosidade no material depositado, assim como ajuda na prevenção de respingos que podem danificar a lente óptica laser[87,115,116].…”

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Desenvolvimento de um processo de soldagem a ponto por resistência elétrica utilizando manufatura aditiva.

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For several decades, the electric resistance spot welding process has been widely used in the manufacture of sheet metal structures mainly in automotive bodies. It has been noted that during this period there was no significant development for this welding process. However, in the last few years, in order to meet the demand for lighter, more economical, safer and lower cost vehicles due to environmental requirements, the automotive manufacturing industry is undergoing a revolution in the use of combinations of steel sheets with high mechanical resistance, different chemical compositions and thicknesses. Within this context, the present work will be focused on the study and development of a new spot welding technology using additive manufacturing in zinc coated and uncoated steel sheets employed in the automotive industry. By way of comparison, a spot welding by the conventional process was also performed. In order to find the optimal welding parameters, weldability diagrams were made.Subsequently, using the optimized parameters, the mechanical properties were analyzed through tensile tests (tensile shear test, pull test and cross tension test) and fatigue tests in cyclic loads. In order to understand the phenomena occurred during welding, the behaviors of the dynamic resistances, the magnitudes of the welding electric energies, the force between the electrodes and the thermal expansion of the weld spot were studied and analyzed. For the analysis of the geometrical dimensions and the metallurgical phenomena of the weld spot, macrographs, micrographs, chemical composition and Vickers microhardness tests were performed. Corrosion tests were also carried out in salt spray on painted plates according to the automotive industry process. What stands out among the results is that the spot welding process using additive manufacturing (AMSW), through the optimized parameters, compared to the conventional spot welding process (RSW) showed higher efficiency in heat energy generation, lower force between the electrodes, higher maximum tensile stress in relation to the tests of: shear, pull and cross-tension (tensile perpendicular to the weld point).It was also observed that the fatigue limits showed no significant differences and that in the salt spray tests no corrosion was observed for both spot welding processes.

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Numerical investigation of gas-disperse jet flows created by coaxial nozzles during the laser direct material deposition

Cited by 66 publications

References 21 publications

Experimental and Numerical Analysis of Gas/Powder Flow for Different LMD Nozzles

Experimental and Numerical Analysis of Gas/Powder Flow for Different LMD Nozzles

Statistical/Numerical Model of the Powder-Gas Jet for Extreme High-Speed Laser Material Deposition

Desenvolvimento de um processo de soldagem a ponto por resistência elétrica utilizando manufatura aditiva.

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