scholarly journals Influence of Cross-Wind on CO2 Arc Welding of Carbon Steel

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1677
Author(s):  
Shinichi Tashiro ◽  
Ngoc Quang Trinh ◽  
Tetsuo Suga ◽  
Natsume Matsuda ◽  
Naotaka Tsurumaru ◽  
...  
Keyword(s):  
Nozzle Exit ◽  
Gas Flow ◽  
Cfd Simulation ◽  
Shielding Effect ◽  
Shielding Gas ◽  
Effective Parameters ◽  
Wind Resistance ◽  
Welding Torch ◽  
The Cross ◽  
Gas Flow Velocity

The purpose of this study is to develop a novel welding torch with high wind resistance, which can be used for welding outside a building under strong cross-wind. In this paper, a parametric study was carried out using different torch nozzle designs and shield gas flow rates for their optimization. The gas flow around the torch nozzle exit was visualized through the shadowgraph method to evaluate the interaction between the shielding gas flow and the cross-wind. Nitrogen fraction in a weld bead was measured for confirming the shielding effect. Furthermore, CFD simulation was also carried out for obtaining shielding gas flow velocity at the torch nozzle exit. From the result of the above experiments and simulation, effective parameters for improving the shielding effect against the cross-wind were comprehensively discussed. As a result, the nitrogen fraction was found to be decreased by increasing the averaged vertical gas velocity at the torch nozzle exit. For achieving this, it is especially effective to decrease the nozzle diameter or increase the gas flow rate.

scholarly journals Numerical Simulation of the Behavior of Hydrogen Source in a Novel Welding Process to Reduce Diffusible Hydrogen

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1619 ◽  
Author(s):  
Shinichi Tashiro ◽  
Naoki Mukai ◽  
Yoshihide Inoue ◽  
Anthony B. Murphy ◽  
Tetsuo Suga ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Arc Welding ◽  
Gas Flow ◽  
Operating Conditions ◽  
Shielding Gas ◽  
Diffusible Hydrogen ◽  
Welding Torch ◽  
Deposited Metal ◽  
Suction Nozzle ◽  
Gas Nozzle

This study aims to reduce the diffusible hydrogen content in deposited metal during gas metal arc welding (GMAW) and flux-cored arc welding (FCAW) which induces cold cracking. To achieve this, a novel welding torch with a dual gas nozzle has been developed. This special welding torch decreases the hydrogen source gas evaporated from a welding wire by the suction from the inner gas nozzle. In order to improve the suction efficiency of this evaporated gas, precise control of the suction gas flow is indispensable. In this paper, a simplified numerical simulation model of this process has been described. This model can take account of the evaporation of the hydrogen source gas from the wire while simulating the behavior of the shielding gas and the arc. Using this model, the effect of suction nozzle structure and torch operating conditions on suction gas flow pattern and suction efficiency was also investigated to understand the process mechanism. Furthermore, the diffusible hydrogen content in deposited metal was measured by chromatography as a validation step. Results show that some of the shielding gas introduced from a shielding nozzle was drawn inward and also branched into an upward flow that was sucked into the suction nozzle and a downward flow to a base metal. This branching height was defined as the suction limit height, which decisively governed the suction efficiency. As a result, in order to reduce the diffusible hydrogen, it was suggested that the suction limit height should be controlled towards below the wire position, where the evaporation rate of the hydrogen source gas peaks through optimization of the suction nozzle design and the torch operating conditions.

scholarly journals CFD Simulation of Dry Pressure Drop in a Cross-Flow Rotating Packed Bed

2021 ◽  
Vol 11 (21) ◽  
pp. 10099
Author(s):  
Chao Zhang ◽  
Weizhou Jiao ◽  
Youzhi Liu ◽  
Guisheng Qi ◽  
Zhiguo Yuan ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Gas Flow ◽  
Cfd Simulation ◽  
Complex Structure ◽  
Scale Up ◽  
Cross Flow ◽  
Packed Bed ◽  
Rotating Packed Bed ◽  
Porous Media Model ◽  
The Cross

The cross-flow rotating packed bed (RPB) has attracted wide attention in recent years because of its advantages of large gas capacity, low pressure drop and lack of flooding limitation. However, the complex structure of the packing makes it difficult to obtain the gas flow characteristics in the cross-flow RPB by experiments. In this study, the dry pressure drop in the cross-flow RPB was investigated by computational fluid dynamics (CFD). The packing was modeled by the porous media model and the rotation of the packing was simulated by the sliding mesh model. The simulation results obtained by three turbulence models were compared with experimental results, and the RNG k-ε model was found to best describe the turbulence behaviors in the cross-flow RPB. Then, the effects of gas flow rate and rotating speed on dry pressure drop in different parts of the cross-flow RPB were analyzed. The results of this study can provide important insights into the design and scale-up of cross-flow RPB.

Limitations of the Schlieren technique for shielding gas flow visualization in arc welding processes

2021 ◽  
Author(s):  
Mateus Barancelli Schwedersky ◽  
Álisson Fernandes da Rosa ◽  
Marcelo Pompermaier Okuyama ◽  
Régis Henrique Gonçalves e Silva
Keyword(s):  
Flow Visualization ◽  
Arc Welding ◽  
Gas Flow ◽  
Shielding Gas ◽  
Schlieren Technique ◽  
Welding Processes

scholarly journals Strategies to Reduce Porosity in Al-Mg WAAM Parts and Their Impact on Mechanical Properties

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 524
Author(s):  
Maider Arana ◽  
Eneko Ukar ◽  
Iker Rodriguez ◽  
Amaia Iturrioz ◽  
Pedro Alvarez
Keyword(s):  
Mechanical Properties ◽  
Gas Flow ◽  
Bottom Layer ◽  
Local Heat ◽  
High Porosity ◽  
Shielding Gas ◽  
Heat Accumulation ◽  
High Mechanical Property ◽  
Building Conditions ◽  
Static Tensile

With the advent of disruptive additive manufacturing (AM), there is an increasing interest and demand of high mechanical property aluminium parts built directly by these technologies. This has led to the need for continuous improvement of AM technologies and processes to obtain the best properties in aluminium samples and develop new alloys. This study has demonstrated that porosity can be reduced below 0.035% in area in Al-Mg samples manufactured by CMT-based WAAM with commercial filler metal wires by selecting the correct shielding gas, gas flow rate, and deposition strategy (hatching or circling). Three phase Ar+O2+N2O mixtures (Stargold®) are favourable when the hatching deposition strategy is applied leading to wall thickness around 6 mm. The application of circling strategy (torch movement with overlapped circles along the welding direction) enables the even build-up of layers with slightly thicker thickness (8 mm). In this case, Ar shielding gas can effectively reduce porosity if proper flow is provided through the torch. Reduced gas flows (lower than 30 Lmin) enhance porosity, especially in long tracks (longer than 90 mm) due to local heat accumulation. Surprisingly, rather high porosity levels (up to 2.86 area %) obtained in the worst conditions, had a reduced impact on the static tensile test mechanical properties, and yield stress over 110 MPa, tensile strength over 270 MPa, and elongation larger than 27% were achieved either for Ar circling, Ar hatching, or Stargold® hatching building conditions. In all cases anisotropy was lower than 11%, and this was reduced to 9% for the most appropriate shielding conditions. Current results show that due to the selected layer height and deposition parameters there was a complete re-melting of the previous layer and a thermal treatment on the prior bottom layer that refined the grain size removing the original dendritic and elongated structure. Under these conditions, the minimum reported anisotropy levels can be achieved.

scholarly journals GMAW Shielding Gas Flow Optimisation by Refinement of Nozzle Geometry

PRICM ◽  
2013 ◽  
pp. 2131-2137
Author(s):  
S.W. Campbell ◽  
A.M. Galloway ◽  
N.A. McPherson
Keyword(s):  
Gas Flow ◽  
Nozzle Geometry ◽  
Shielding Gas

An analysis of the shielding gas flow from a coaxial conical nozzle during high power CO2laser welding

2006 ◽  
Vol 39 (3) ◽  
pp. 563-574 ◽  
Author(s):  
Antonio Ancona ◽  
Teresa Sibillano ◽  
Pietro Mario Lugarà ◽  
Giuseppe Gonnella ◽  
Giuseppe Pascazio ◽  
...  
Keyword(s):  
High Power ◽  
Gas Flow ◽  
Conical Nozzle ◽  
Shielding Gas

Analysis of a Virtual Prototype First-Stage Rotor Blade Using Integrated Computer-Based Design Tools

2006 ◽  
Author(s):  
Michel Arnal ◽  
Christian Precht ◽  
Thomas Sprunk ◽  
Tobias Danninger ◽  
John Stokes
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Thermal Loading ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Life Assessment ◽  
Element Analysis ◽  
Pressure Losses ◽  
Cooling Channels ◽  
Internally Cooled

The present paper outlines a practical methodology for improved virtual prototyping, using as an example, the recently re-engineered, internally-cooled 1st stage blade of a 40 MW industrial gas turbine. Using the full 3-D CAD model of the blade, a CFD simulation that includes the hot gas flow around the blade, conjugate heat transfer from the fluid to the solid at the blade surface, heat conduction through the solid, and the coolant flow in the plenum is performed. The pressure losses through and heat transfer to the cooling channels inside the airfoil are captured with a 1-D code and the 1-D results are linked to the three-dimensional CFD analysis. The resultant three-dimensional temperature distribution through the blade provides the required thermal loading for the subsequent structural finite element analysis. The results of this analysis include the thermo-mechanical stress distribution, which is the basis for blade life assessment.

scholarly journals Visualisation of alternating shielding gas flow in GTAW

2016 ◽  
Vol 91 ◽  
pp. 424-431 ◽  
Author(s):  
I. Bitharas ◽  
S.W. Campbell ◽  
A.M. Galloway ◽  
N.A. McPherson ◽  
A.J. Moore
Keyword(s):  
Gas Flow ◽  
Shielding Gas

scholarly journals Influence of Laser Energy Input and Shielding Gas Flow on Evaporation Fume during Laser Powder Bed Fusion of Zn Metal

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2677
Author(s):  
Yu Qin ◽  
Jinge Liu ◽  
Yanzhe Chen ◽  
Peng Wen ◽  
Yufeng Zheng ◽  
...  
Keyword(s):  
Energy Input ◽  
Gas Flow ◽  
Evaporation Rate ◽  
Laser Energy ◽  
Circulation System ◽  
Powder Bed Fusion ◽  
Shielding Gas ◽  
Laser Powder Bed Fusion ◽  
Conservation Of Energy ◽  
Powder Bed

Laser powder bed fusion (LPBF) of Zn-based metals exhibits prominent advantages to produce customized biodegradable implants. However, massive evaporation occurs during laser melting of Zn so that it becomes a critical issue to modulate laser energy input and gas shielding conditions to eliminate the negative effect of evaporation fume during the LPBF process. In this research, two numerical models were established to simulate the interaction between the scanning laser and Zn metal as well as the interaction between the shielding gas flow and the evaporation fume, respectively. The first model predicted the evaporation rate under different laser energy input by taking the effect of evaporation on the conservation of energy, momentum, and mass into consideration. With the evaporation rate as the input, the second model predicted the elimination effect of evaporation fume under different conditions of shielding gas flow by taking the effect of the gas circulation system including geometrical design and flow rate. In the case involving an adequate laser energy input and an optimized shielding gas flow, the evaporation fume was efficiently removed from the processing chamber during the LPBF process. Furthermore, the influence of evaporation on surface quality densification was discussed by comparing LPBF of pure Zn and a Titanium alloy. The established numerical analysis not only helps to find the adequate laser energy input and the optimized shielding gas flow for the LPBF of Zn based metal, but is also beneficial to understand the influence of evaporation on the LPBF process.

The Features of Measuring the Gas Flow Velocity in Pipes by an Ultrasonic Correlation Method

2021 ◽  
Vol 67 (2) ◽  
pp. 216-221
Author(s):  
A. D. Mansfeld ◽  
G. P. Volkov ◽  
R. V. Belyaev ◽  
A. G. Sanin ◽  
P. R. Gromov ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Gas Flow ◽  
Correlation Method ◽  
Gas Flow Velocity
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