Modeling of GMA Weld Pools With Consideration of Droplet Impact

1998 ◽  
Vol 120 (4) ◽  
pp. 313-320 ◽  
Author(s):  
Zhen Ning Cao ◽  
Pingsha Dong
Keyword(s):  
Fluid Flow ◽  
Weld Pool ◽  
Surface Deformation ◽  
Impact Force ◽  
Gma Welding ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Heat Content ◽  
Heat Transfer Process ◽  
Droplet Impact

A three-dimensional weld pool model has been developed to study the fluid flow and heat transfer process during gas metal arc (GMA) welding. Both droplet heat content and impact force were considered in analyzing the effect of droplets on the formation of weld pool. The fluid flow in the weld pool was induced by the presence of surface tension, electromagnetic and buoyancy force. The surface deformation of weld pool was calculated by considering arc pressure and droplet impact force. Computational results under partial and full penetration welding conditions were obtained. The effect of heat flow and fluid flow characteristics on weld pool geometry was discussed, particularly with respect to the presence of droplet heat input and impact force.

A Study on the Three-Dimensional Analysis of Heat and Fluid Flow in Gas Metal Arc Welding Using Boundary-Fitted Coordinates

1994 ◽  
Vol 116 (1) ◽  
pp. 78-85 ◽  
Author(s):  
J.-W. Kim ◽  
S.-J. Na
Keyword(s):  
Surface Tension ◽  
Fluid Flow ◽  
Weld Pool ◽  
Surface Deformation ◽  
Driving Forces ◽  
Gma Welding ◽  
Gas Metal Arc Welding ◽  
Three Dimensional ◽  
Weld Bead ◽  
Surface Boundary

Computer simulation of three-dimensional heat transfer and fluid flow in gas metal arc (GMA) welding has been studied by considering the three driving forces for weld pool convection, that is the electromagnetic force, the buoyancy force, and the surface tension force at the weld pool surface. Molten surface deformation, particularly in the case of GMA welding, plays a significant part in the actual weld size and should be considered in order to accurately evaluate the weld pool convection. The size and profile of the weld pool are strongly influenced by the volume of molten electrode wire, impinging force of the arc plasma, and surface tension of molten metal. In the numerical simulation, difficulties associated with the irregular shape of the weld bead have been successfully overcome by adopting a boundary-filled coordinate system that eliminates the analytical complexity at the weld pool and bead surface boundary. The method used in this paper has the capacity to determine the weld bead and penetration profile by solving the surface equation and convection equations simultaneously.

Arc Behavior Numerical Analysis in GMAW Welding Deposition-Based Rapid Forming

2014 ◽  
Vol 488-489 ◽  
pp. 285-288
Author(s):  
Feng Liang Yin ◽  
Sheng Zhu ◽  
Hong Wei Liu ◽  
Lei Guo
Keyword(s):  
Heat Flux ◽  
Fluid Flow ◽  
Weld Pool ◽  
Numerical Study ◽  
Three Dimensional ◽  
Radial Distance ◽  
Maximum Pressure ◽  
Forming Process ◽  
Arc Behavior ◽  
Gmaw Welding

Metal fluid flow in weld pool would influence final quality of forming part in GMAW welding deposition-based rapid forming process. To numerical study fluid flow in weld pool, heat and force effects on weld pool surface must been made clear firstly. A three-dimensional numerical model has been built to study arc behavior in GMAW welding deposition-based rapid forming process. Solving the model, heat flux and pressure distributions on the cathode were derived. Calculated results show that heat flux from the arc to the cathode is related to arc temperature nearly above the cathode, and is not monotonous about radial distance within 2 mm distance away from arc axis. A maximum pressure with a value of 800 Pa happens at 1mm away from arc axis.

Modeling the Transport Phenomena During Hybrid Laser-MIG Welding Process

2003 ◽  
Author(s):  
Z. Zhou ◽  
W. H. Zhang ◽  
H. L. Tsai ◽  
S. P. Marin ◽  
P. C. Wang ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Weld Pool ◽  
Solid Phase ◽  
Three Dimensional ◽  
Welding Process ◽  
Weld Bead ◽  
Mig Welding ◽  
Multiple Reflections ◽  
Computer Animations ◽  
Solidification Processes

Hybrid laser-MIG welding technology has several advantages over laser welding alone or MIG welding alone. These include the possibility of modifying weld bead shape including the elimination of undercut, the change of weld compositions, and the reduction of porosity formation in the weld. Although the hybrid laser-MIG welding method is becoming popular in industry, its development has been based on the trial-and-error procedure. In this paper, mathematical models and the associated numerical techniques were developed to calculate the heat and mass transfer and fluid flow during the laser-MIG welding process. The continuum formulation was used to handle solid phase, liquid phase, and mushy zone during the melting and solidification processes. The volume-of-fluid (VOF) method was employed to handle free surfaces, and the enthalpy method was used for latent heat. The absorption (Inverse Bremsstrahlung and Fresnel absorption) and the thermal radiation by the plasma in the keyhole, and multiple reflections at the keyhole wall were all considered in the models. The transient keyhole dynamics, interactions between droplets and weld pool, and the shape and composition of the solidified weld bead were all predicted for both the pulsed laser-MIG welding and three-dimensional moving laser-MIG welding. Computer animations showing the fluid flow, weld pool dynamics, and the interaction between droplets and weld pool will be shown in the presentation.

scholarly journals Fluid Flow Characteristics and Weld Formation Quality in Gas Tungsten Arc Welding of a Thick-Sheet Aluminum Alloy Structure by Varying Welding Position

2018 ◽  
Vol 8 (8) ◽  
pp. 1215 ◽  
Author(s):  
Baohua Chang ◽  
Hong Xiao ◽  
Jinle Zeng ◽  
Shuo Yang ◽  
Dong Du ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Molten Metal ◽  
Weld Pool ◽  
Flow Characteristics ◽  
Sheet Thickness ◽  
Thick Sheet ◽  
Weld Formation ◽  
Sheet Aluminum ◽  
Weld Pools ◽  
Welding Position

This study aims to reveal the cause of different weld formation quality for varying welding position in the GTAW (Gas Tungsten Arc Welding) of a thick-sheet aluminum alloy structure. The fluid flow characteristics of weld pools are investigated by CFD (Computational Fluid Dynamic) modeling and high-speed imaging for the climbing and flat welding positions, which correspond to the start and finish ends of the welds of the structure, respectively. Results show that the directions of gravity relative to weld pools may notably affect the fluid flows in weld pools for different welding positions. For flat welding, gravity will accelerate the fluid flow in the direction of sheet thickness only and in turn result in a high velocity downwards, which implies a good penetrating capability. Welds of good formation with smooth surface and consistent width can be produced under flat welding position. In contrast, for climbing welding, gravity will act on the molten metal in both the direction of sheet thickness and the lateral direction of the weld pool. As a result, the velocity in sheet-thickness direction is decreased, which implies a decreased penetrating capability. Meanwhile, the velocity backwards is increased in the top portion of the weld pool, which makes the molten metal apt to flow out of the weld pool. Both the decreased penetrating capability and the accelerated molten metal outflow would render the climbing welding process unstable, and result in welds of poor formation with uneven weld surface and inconsistent weld width. Based on the study, possible methods are proposed that could be used to improve the weld formation quality when welding thick-sheet aluminum alloys structures using various welding positions.

Flow Development and Analysis of MHD Generators and Seawater Thrusters

1992 ◽  
Vol 114 (1) ◽  
pp. 68-72 ◽  
Author(s):  
E. D. Doss ◽  
G. D. Roy
Keyword(s):  
Fluid Flow ◽  
Skin Friction ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Plasma Generator ◽  
Electrical Fields ◽  
Mhd Generator ◽  
Flow Development ◽  
Electrode Wall ◽  
Plasma Generators

The flow characteristics inside magnetohydrodynamic (MHD) plasma generators and seawater thrusters are analyzed and are compared using a three-dimensional computer model that solves the governing partial differential equations for fluid flow and electrical fields. Calculations have been performed for a Faraday plasma generator and for a continuous electrode seawater thruster. The results of the calculations show that the effects caused by the interaction of the MHD forces with the fluid flow are strongly manifested in the case of the MHD generator as compared to the flow development in the MHD thruster. The existence of velocity overshoots over the sidewalls confirm previously published results for MHD generators with strong MHD interaction. For MHD thrusters, the velocity profile is found to be slightly flatter over the sidewall as compared to that over the electrode wall. As a result, distinct enhancement of the skin friction exists over the sidewalls of MHD generators in comparison to that of MHD thrusters. Plots of velocity profiles and skin friction distributions are presented to illustrate and compare the flow development in MHD generators and thrusters.

Three-Dimensional Liquid Sloshing Numerical Analysis on a New Designed Tank Container

2019 ◽  
Author(s):  
Wenjun Yue ◽  
Xu Chen
Keyword(s):  
Fluid Flow ◽  
Carrying Capacity ◽  
Impact Force ◽  
Three Dimensional ◽  
Economic Benefits ◽  
Cylindrical Vessel ◽  
Filling Ratio ◽  
Operating Conditions ◽  
New Type ◽  
Maximum Impact Force

Abstract Based on the conventional tank container which has a cylindrical vessel, a new structure of tank container was designed to improve the carrying capacity of the tank. Fluid flow inside the new tank container under different operating conditions (liquid filling ratio K, braking deceleration a, filling medium, no baffle and with baffles) was studied. A volume-of-fluid (VOF) method and a k-epsilon (k-ε) turbulence model were used to simulate the fluid flow. Results showed that all the factors studied in this work had an influence on the tank. The maximum impact force increased with the increasing of a and K. A clear linear positive correlation was found between the maximum impact force and braking deceleration. Besides, the maximum impact force had a relationship with the density of medium. Compared with the conventional tank container, the carrying capacity of the new type tank container increases by 11.8%, which means the new type tank container has better economic benefits.

Determining the distribution of the heat content of filler metal droplets transferred into gas—metal arc weld pools

1998 ◽  
Vol 212 (7) ◽  
pp. 525-531 ◽  
Author(s):  
C S Wu ◽  
J S Sun
Keyword(s):  
Weld Pool ◽  
Marked Effect ◽  
Filler Metal ◽  
Gma Welding ◽  
Internal Heat ◽  
Heat Content ◽  
Physical Reality ◽  
Temperature Variations ◽  
Weld Thermal Cycle ◽  
Metal Droplets

The distribution of the heat content of filler metal droplets inside the gas—metal arc (GMA) weld pool has a marked effect on the weld bead dimensions and the weld thermal cycle. A model is developed to account for this distribution. Volumetric distribution of the heat content of droplets within the weld pool is considered as an internal heat generation term. Based on physical reality, an algorithm is proposed to determine the geometry and size of the volume within which the heat content of droplets is distributed. Bead-on-plate GMA welding experiments show that the predicted weld dimensions and temperature variations are in agreement with the measured values.

scholarly journals Numerical Simulation of Full-Scale Three-Dimensional Fluid Flow in an Oscillating Reactor

2021 ◽  
Vol 9 ◽  
Author(s):  
Houjun Gong ◽  
Mengqi Wu
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Flow Field ◽  
Flow Rate ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Full Scale ◽  
Variation Patterns ◽  
Oscillating Motion ◽  
Resistance Coefficients

Marine reactors are subjected to additional motions due to ocean conditions. These additional motions will cause large fluctuation of flow rate and change the coolant flow field, making the system unstable. Therefore, in order to understand the effect of oscillating motion on the flow characteristics, a numerical simulation of fluid flow is carried out based on a full-scale three-dimensional oscillating marine reactor. In this study, the resistance coefficients of the lattice, rod buddle and steam generator are fitted, and the distribution of flow rate, velocity as well as pressure in different regions is investigated through the standard model. After additional oscillation is introduced, the flow field in an oscillating reactor is presented and the effect of oscillating angle and elevation on the flow rate is investigated. Results show that the oscillating motion can greatly change the flow field in the reactor; most of the coolant circulates in the downcommer and lower head with only a small amount of coolant entering the core; the flow fluctuation period is consistent with the oscillating period, and the flow variation patterns under different oscillating conditions are basically the same; since the flow amplitude is related to oscillating speed, the amplitude of flow rate rises when decreasing the maximum oscillating angle; the oscillating elevation has little effect on the flow rate.

Experimental and SPH studies of reciprocal wet-bed dam-break flow over obstacles

2021 ◽  
pp. 2150098
Author(s):  
Armin Ansari ◽  
Ehsan Khavasi ◽  
Jafar Ghazanfarian
Keyword(s):  
Surface Deformation ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Dam Break ◽  
Experimental Results ◽  
Mesh Free ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Dam Break Flow ◽  
Velocity Effect

Different permutations of the single and the two-fold dam-break flow have been investigated using the mesh-free smoothed-particle hydrodynamics and the experimental setup. The free-surface deformation in the case with the wet bed for five different downstream water heights has been investigated and respective numerical and experimental results were presented. The results demonstrate that the increase of the water height over the wet bed leads to the reduction of the flow front velocity. Effect of considering or omitting the dam gate during the numerical simulation has also been examined, which proves that the simulations including the dam gate show improved agreement with the experimental results. Influence of the three-dimensional cubic, triangular, circular and square cylindrical obstacles and their position on flow characteristics has been investigated. As the distance between the triangular obstacle and the gate increases, a bore is created at the position closer to the top of the triangle. In addition, it is found that larger force is exerted on the circular cylinder in comparison to the square cylinder.

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