Measurement of Surface Temperature Field Distribution in Molten Pool of Laser Cladding

To discuss the effect of temperature field distribution on the curvature change and layer thickness of thin-wall parts, the numerical simulation and experimental was studied. The numerical results showed that the molten pool temperature of the thin-wall increases with the layer number, and the molten pool temperature of thin-wall cylinders were increases when decrease curvature radius; the rules of laser power changing with the layer number and curvature in the processing of the thin-wall blade can be obtained when keeping molten pool temperature stable. According to the numerical results, the thin-wall blades were fabricated by experiments. The experimental results showed that the excessive build-up occurred and unevenness thickness layer at small radius corner with constant laser power because of the increase of energy density at corners, with varied laser power is more uniform than the constant laser power, which is in agreement with the numerical simulation.

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Three-Dimensional Electro-Thermal Analysis of a New Type Current Transformer Design for Power Distribution Networks

Energies ◽

10.3390/en14061792 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1792

Author(s):

Bingbing Dong ◽

Yu Gu ◽

Changsheng Gao ◽

Zhu Zhang ◽

Tao Wen ◽

...

Keyword(s):

Boundary Condition ◽

Temperature Field ◽

Temperature Gradient ◽

Field Distribution ◽

Distribution Network ◽

Current Transformer ◽

Internal Temperature ◽

Temperature Field Distribution ◽

Type Design ◽

New Type

In recent years, the new type design of current transformer with bushing structure has been widely used in the distribution network system due to its advantages of miniaturization, high mechanical strength, maintenance-free, safety and environmental protection. The internal temperature field distribution is an important characteristic parameter to characterize the thermal insulation and aging performance of the transformer, and the internal temperature field distribution is mainly derived from the joule heat generated by the primary side guide rod after flowing through the current. Since the electric environment is a transient field and the thermal environment changes slowly with time as a steady field under the actual conditions, it is more complex and necessary to study the electrothermal coupling field of current transformer (CT). In this paper, a 3D simulation model of a new type design of current transformer for distribution network based on electric-thermal coupling is established by using finite element method (FEM) software. Considering that the actual thermal conduction process of CT is mainly by conduction, convection and radiation, three different kinds of boundary conditions such as solid heat transfer boundary condition, heat convection boundary condition and surface radiation boundary condition are applied to the CT. Through the model created above, the temperature rise process and the distribution characteristics of temperature gradient of the inner conductor under different current, different ambient temperatures and different core diameters conditions are studied. Meanwhile, the hottest temperature and the maximum temperature gradient difference are calculated. According to this, the position of weak insulation of the transformer is determined. The research results can provide a reference for the factory production of new type design of current transformer.

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Study on the Influence of Surface Temperature Field of Aluminum Alloy Etched by Laser Water Jet Composite Machining

Materials ◽

10.3390/ma13143206 ◽

2020 ◽

Vol 13 (14) ◽

pp. 3206

Author(s):

Xuehui Chen ◽

Xin Xu ◽

Wei Liu ◽

Lei Huang ◽

Hao Li ◽

...

Keyword(s):

Aluminum Alloy ◽

Temperature Field ◽

Surface Temperature ◽

Process Parameters ◽

Water Jet ◽

Laser Machining ◽

Material Surface ◽

Laser Etching ◽

Surface Temperature Field

This paper studies the compound effect of liquid medium and laser on the workpiece and analyses the law of material surface temperature change during the processing. Taking 7075-T6 aluminum alloy as the research object, the surface temperature field of aluminum alloy processed using water-jet-assisted laser machining under different process parameters was simulated using finite element software. In addition, the temperature field of the material surface was detected in real-time using the self-built water-jet-assisted laser machining temperature field detection system, and the processing results were observed and verified using an optical microscope, scanning electron microscope, and energy spectrum analyzer. The results show that when the water jet inflow angle is 45°, the heat-affected area of the material surface is the smallest, and the cooling effect of the temperature field of the material surface is better. Considering the liquidus melting point of 7075 aluminum alloys, it is concluded that the processing effect is better when the water jet velocity is 14 m·s−1, the laser power is 100 W, and the laser scanning speed is 1.2 mm·s−1. At this time, the quality of the tank is relatively good, there are no cracks in the bottom of the tank, and there is less slag accumulation. Compared with anhydrous laser etching, water-jet-assisted laser etching can reduce the problems of micro-cracks, molten slag, and the formation of a recast layer in laser etching and improve the quality of the workpiece, and the composition of the bottom slag does not change. This study provides theoretical guidance and application support for the selection and optimization of process parameters for water-jet-assisted laser etching of aluminum alloy and further enriches the heat transfer mechanism of multi-field coupling in the process of water-jet-assisted laser machining.

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