Article
Physics, Applied
Dongsheng Wu, Shinichi Tashiro, Xueming Hua, Manabu Tanaka
Summary: A three-dimensional numerical model was developed to investigate the keyhole behavior and energy transfer in plasma arc welding of an aluminum alloy. The study revealed the coupled mechanisms of keyhole, energy transfer, and compositional change in the welding process, showing that with a keyhole, the arc energy efficiency decreases due to increased arc energy loss and input.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Engineering, Manufacturing
Xumin Guo, Zuming Liu, Xingchuan Zhao, Wenbin Zhang
Summary: Controlling heat output and force in the arc source is crucial for improving keyhole stability in welding. This study developed a double-layer hybrid arc torch by adding two outer tungsten electrodes symmetrically. The results showed that the hybrid arc with two free arcs had symmetrical arc pressure. The additional heat input from the free arcs could be transferred into the keyhole bottom, requiring less constraint arc current to form a stable fully penetrated keyhole.
JOURNAL OF MANUFACTURING PROCESSES
(2023)
Article
Mechanics
Bin Xu, Shujun Chen, Shinichi Tashiro, Fan Jiang, Manabu Tanaka
Summary: Through keyhole morphology analysis and x-ray in situ imaging experiments, this study reveals the mechanism behind the stability of the keyhole weld pool and the reason for the very narrow process parameter window in VPPA welding processes. The influence of the difference in plasma arc pressure and the keyhole boundary on the flow field may guide the optimization process of light metal joining for efficient and defect-free manufacturing of large and complex structures.
Article
Engineering, Manufacturing
Yu Liu, ZuMing Liu
Summary: Keyhole behavior and weld pool thermal state have a significant impact on the stability of the plasma arc welding process. This research proposes a new method to evaluate the weld pool thermal state by analyzing the front side reflected plasma angle. Experimental results show that the reflected plasma angle is related to the weld pool thermal state.
JOURNAL OF MANUFACTURING PROCESSES
(2022)
Article
Materials Science, Multidisciplinary
Xinglin Miao, Hongtao Zhang, Fuchen Ge, Zhenyu He, Jianguo Gao, Zhaofang Su
Summary: In the magnetically controlled Plasma-GMAW welding process, the composite arc forms a keyhole in the workpiece to be welded. The effect of process parameters on arc coupling, weld pool, keyhole, and the behavior characteristics of keyhole were explored. It was found that the coupling degree of the two arcs increases with the increase in plasma current, GMAW current, and magnetic field intensity. The size of the keyhole inlet increases with the increase in plasma current, decreases with the increase of GMAW current, and increases with the increase of magnetic field intensity.
Article
Thermodynamics
Yan Li, Ze Yun, Chen Su, Xiang Zhou, Chuansong Wu
Summary: Plasma arc welding (PAW) is an essential technique in manufacturing. The special keyhole mode, which can achieve full penetration without a groove, has been studied for its potential to improve welding efficiency. A multiphase and multi-physical model was established to understand the complex interactions in the keyhole PAW process, providing insights for improving associated techniques.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Automation & Control Systems
ZuMing Liu, Fei Liu
Summary: Double-layer coaxial hybrid arcing technology is developed to improve the controllability of the weld pool thermal-force state in keyhole welding. The stable hybrid arcing process can be achieved when the outer arc current is lower than 30 A. This method shows promising results in improving the keyhole welding process window.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2023)
Article
Automation & Control Systems
Chuan-Bao Jia, Xin-Feng Liu, Guo-Kai Zhang, Yong Zhang, Chang-Hai Yu, Chuan-Song Wu
Summary: Automatic extraction of weld pool image features based on deep learning algorithm allows accurate prediction of keyhole plasma arc welding (K-PAW) processes, establishing underlying correlations between keyhole status and topside weld pool images.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2021)
Article
Engineering, Industrial
Weilu Zhou, Chuanbao Jia, Fangzheng Zhou, Chuansong Wu
Summary: This paper investigates the keyhole and weld pool behavior in the initial stage of keyhole plasma arc welding (K-PAW) of medium-thick plates. A special visual sensing structure is used to obtain images of the keyhole and weld pool, allowing direct observation of their growth and flow under different welding conditions. The study quantitatively analyzes the trends of keyhole dimensions and classifies the characteristics of weld pool flow. Additionally, the molten metal flow cycle and cloud cluster are observed using a new visual sensing method. The findings provide a more intuitive way to study K-PAW and offer important guidance for the first normal penetration in medium-thickness plate K-PAW processes.
JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
(2023)
Article
Engineering, Manufacturing
Yongfeng Li, Shuoshuo Tian, ChuanSong Wu, Manabu Tanaka
Summary: Comparative experiments were conducted to investigate the effects of ultrasonic vibration on the flow of molten metal, weld pool size, and keyhole size in plasma arc welding. It was found that ultrasonic vibration changed the shape of the keyhole, reduced the size of the molten pool and keyhole entrance, and enhanced the penetration capability of the keyhole.
JOURNAL OF MANUFACTURING PROCESSES
(2021)
Article
Chemistry, Physical
Junnan Qiao, Chuansong Wu, Yongfeng Li
Summary: The study investigates the impact of acoustic radiation force on the plasma arc welding process, showing that it enhances plasma arc pressure and gas shear stress, leading to an improved keyholing capability. Numerical simulations and experimental validation confirm the findings, highlighting the importance of acoustic radiation force in ultrasonic-assisted plasma arc welding.
Article
Computer Science, Artificial Intelligence
Fangzheng Zhou, Xinfeng Liu, Chuanbao Jia, Sen Li, Jie Tian, Weilu Zhou, Chuansong Wu
Summary: This study developed a novel model based on CNN and LSTM to extract both the spatial and temporal features of topside weld pool images, predicting and describing the complex keyhole behaviors. The comparative study showed that the unified CNN-LSTM model significantly improved the prediction accuracy of keyhole/penetration status, with over 80% accuracy even when predicting keyhole behaviors 2 seconds into the future. This model shows promise for intelligent K-PAW technology.
EXPERT SYSTEMS WITH APPLICATIONS
(2024)
Article
Nanoscience & Nanotechnology
Fuyang Gao, Yongjie Cui, Yifan Lv, Wei Yu, Peng Jiang
Summary: In this paper, 12mm Ti6Al4V titanium was welded using keyhole gas tungsten arc welding technology, with microstructure and properties of the welded joint studied. The tensile strength of the joint reaches 925MPa, with good toughness demonstrated in the weld metal.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Automation & Control Systems
Insa Henze, Peer Woizeschke
Summary: The presence of metal vapor affects the stability of arc in arc and hybrid welding. The composition of the metal vapor and the substrate material composition play a key role due to different ionization energies of the material elements. A special setup is used to investigate the influence of metal vapor on the behavior of a vertically oriented arc generated by a separate laser-induced vapor generation welding process. Experimental results show that the arc voltage increases under the presence of metal vapor, leading to a decrease in arc stability.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2023)
Article
Engineering, Multidisciplinary
Wang YiLin, Jiang Ping, Geng ShaoNing, Shu LeShi, Shao XinYu
Summary: This study investigates the instability of extremely narrow keyholes in high-power laser welding and simulates the process using a multiphase flow model. The research finds that excessive energy accumulation causes drastic fluctuations in the keyhole, but suppressing cutting phenomena and accumulation effects can improve the smoothness of the keyhole surface.
SCIENCE CHINA-TECHNOLOGICAL SCIENCES
(2022)
Article
Thermodynamics
Mahsa Taghavi, Swapnil Sharma, Vemuri Balakotaiah
Summary: This study investigates the natural convection effects in the insulation layers of spherical storage tanks and their impact on the tanks' performance. The permeability and Rayleigh number of the insulation material are considered as key factors. The results show that as the Rayleigh number increases, new convective cells emerge and cause the cold boundary to approach the external hot boundary. In the case of large temperature differences, multiple solutions may coexist.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyang Xu, Fangjun Hong, Chaoyang Zhang
Summary: This study introduces a self-induced jet impingement device for enhancing pool boiling performance in high power electronic cooling. Through visualization and parametric investigations, the effects of this device on pool boiling performance are studied, revealing the promotion of additional liquid supply and vapor exhausting. The flow rate of the liquid jet is found to positively impact boiling performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Wenchao Ke, Yuan Liu, Fissha Biruke Teshome, Zhi Zeng
Summary: Underwater wet laser welding (UWLW) is a promising and labor-saving repair technique. A thermal multi-phase flow model was developed to study the heat transfer, fluid dynamics, and phase transitions during UWLW. The results show that UWLW creates a water keyhole, making the welding environment similar to in air laser welding.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Xingrong Lian, Lin Tian, Zengyao Li, Xinpeng Zhao
Summary: This study investigates the heat transfer mechanisms in natural fiber-derived porous structures and finds that thermal radiation has a significant impact on the thermal conductivity in low-density regions, while natural convection rarely occurs. Insulation materials derived from micron-sized natural fibers can achieve minimum thermal conductivity at specific densities. Strategies to lower the thermal conductivity include increasing porosity and incorporating nanoscale pores using nanosize fibers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Yasir A. Malik, Kilian Koebschall, Stephan Bansmer, Cameron Tropea, Jeanette Hussong, Philippe Villedieu
Summary: Ice crystal icing is a significant hazard in aviation, and accurate modeling of sticking efficiency is essential. In this study, icing wind tunnel experiments were conducted to quantify the volumetric liquid water fraction, sticking efficiency, and maximum thickness of ice layers. Two measurement techniques, calorimetry and capacitive measurements, were used to measure the liquid water content and distribution in the ice layers. The experiments showed that increasing wet bulb temperatures and substrate heat flux significantly increased sticking efficiency and maximum ice layer thickness.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinqi Hu, Tongtong Geng, Kun Wang, Yuanhong Fan, Chunhua Min, Hsien Chin Su
Summary: This study experimentally examined the heat dissipation of vibrating fans and demonstrated its inherent mechanism through numerical simulation. The results showed that the flow fields induced by the vibrating blades exhibited pulsating features and formed large-scale and small-scale vortical structures, significantly improving heat dissipation. The study also identified the impacts of different blade structures and developed a trapezoidal-folding blade, which effectively reduced the maximum temperature of the heat source and alleviated high-temperature failure crisis.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Dan-Dan Su, Xiao-Bin Li, Hong-Na Zhang, Feng-Chen Li
Summary: The boiling heat transfer of low-boiling-point working fluid is a common heat dissipation technology in electronic equipment cooling. This study analyzed the interfacial boiling behavior of R134a under different conditions and found that factors such as the initial thickness of the liquid film, solid-liquid interaction force, and initial temperature significantly affect the boiling mode and thermal resistance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyi Wu, Dongke Sun, Wei Chen, Zhenhua Chai
Summary: A unified lattice Boltzmann-phase field scheme is proposed to simulate dendrite growth of binary alloys in the presence of melt convection. The effects of various factors on the growth are investigated numerically, and the model is validated through comparisons and examinations.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shaokun Ge, Ya Ni, Fubao Zhou, Wangzhaonan Shen, Jia Li, Fengqi Guo, Bobo Shi
Summary: This study investigated the temperature distribution of main cables in a suspension bridge during fire scenarios and proposed a prediction model for the maximum temperature of cables in different lane fires. The results showed that vehicle fires in the emergency lane posed a greater thermal threat to the cables.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shuang-Ying Wu, Shi-Yao Zhou, Lan Xiao, Jia Luo
Summary: This paper investigates the two-phase flow and heat transfer characteristics of low-velocity jet impacting on a cylindrical surface. The study reveals that the heat transfer regimes are non-phase transition and nucleate boiling with the increase of heat transfer rate. The effects of jet impact height and outlet velocity on local surface temperatures are pronounced at the non-phase transition stage. The growth rates of heat transfer rate and liquid loss rate increase significantly from the non-phase transition to nucleate boiling stage.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Emad Hasani Malekshah, Wlodzimierz Wlodzimierz, Miros law Majkut
Summary: Cavitation has significant practical importance and can be controlled by air injection. This study investigates the natural to ventilated cavitation process around a hydrofoil through numerical and experimental methods. The results show that the location and rate of air injection have a meaningful impact on the characteristics of cavitation.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Feriel Yahiat, Pascale Bouvier, Antoine Beauvillier, Serge Russeil, Christophe Andre, Daniel Bougeard
Summary: This study explores the enhancement of mixing performance in laminar flow equipment by investigating the generation of chaotic advection using wall deformations in annular geometries. The findings demonstrate that the combined geometry can achieve perfect mixing at various Reynolds numbers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Hui He, Ning Lyu, Caihua Liang, Feng Wang, Xiaosong Zhang
Summary: This study investigates the condensation, frosting, and defrosting processes on superhydrophobic surfaces with millimeter-scale structures. The results reveal that the structures can influence the growth and removal of frost crystals, with the bottom grooves creating a frost-free zone and conical edges promoting higher frost crystal heights. Two effective methods for defrosting are observed: hand-lifting the groove and airfoil retraction contraction on protruding structures. This research provides valuable insights into frost formation and defrosting on millimeter-structured superhydrophobic surfaces, with potential applications in anti-frost engineering.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Thiwanka Arepolage, Christophe Verdy, Thibaut Sylvestre, Aymeric Leray, Sebastien Euphrasie
Summary: This study developed two thermal concentrators, one with a 2D design of uniform thickness and another with a 3D design, using the coordinate transformation technique and metamaterials. By structuring the thermal conductor, the desired local density-heat capacity product and anisotropic thermal conductivities were achieved. The homogenized thermal conductivities were obtained from finite element simulations and cylindrical symmetry consideration. A 3D concentrator was fabricated using 3D metal printing and characterized using a thermal camera. Compared to devices that solely consider anisotropic conductivities, the time evolution characteristics of the metadevice designed with coordinate transformation were closer to those of an ideal concentrator.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Liangyuan Cheng, Qingyang Wang, Jinliang Xu
Summary: In this study, we investigated the supercritical heat transfer of CO2 in a horizontal tube with a diameter of 10.0 mm, covering a wide range of pressures, mass fluxes, and heat fluxes. The study revealed a non-monotonic increase in wall temperatures along the flow direction and observed both positive and negative wall temperature differences between the bottom and top tube. The findings were explained by the thermal conduction in the solid wall interacting with the stratified-wavy flow in the tube.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)