Heat Source Characteristics of Ternary-Gas-Shielded Tandem Narrow-Gap GMAW

: The characteristics of the welding heat source for tandem narrow-gap gas metal arc welding are examined for different ternary shielding gas (Ar-CO2-He) compositions. Results of previous calculations of arc properties for bead-on-plate geometry are adapted to the narrow-gap geometry to predict these characteristics. The heat source concentration factor decreases and the maximum heat flux density increases as the helium content increases, which leads to an increased welding heat efficiency. Addition of CO2 up to around 10% also increases the heat efficiency. When the CO2 content exceeds 10%, the heat source concentration factor increases significantly and the heat efficiency decreases. The shielding gas composition also affects the heat source distribution. The heat source characteristics are applied to a computational fluid dynamic model of the weld pool to predict the weld shape, and the predictions are verified by experiment. The results indicate that the appropriate addition of helium to the shielding gas can increase the heat transferred to the peripheral regions of the arc and increase the sidewall penetration.

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HEAT SOURCE FOR TIG WELDING MODELLING

Environment Technology Resources Proceedings of the International Scientific and Practical Conference ◽

10.17770/etr2021vol3.6601 ◽

2021 ◽

Vol 3 ◽

pp. 348-356

Author(s):

Manahil Tongov

Keyword(s):

Heat Source ◽

Concentration Factor ◽

Tig Welding ◽

Experimental Results ◽

New Model ◽

Heating Spot ◽

Spot Radius ◽

Calibration Parameters ◽

Source Concentration

A new model of heat source applicable to TIG welding is proposed. The model uses three calibration parameters - efficiency, effective heating spot radius and heat source concentration factor. Based on the experimental results, the model was calibrated and the results obtained for the form of penetration were compared with the experimental ones.

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Diagnostic of Heat Source Characteristics in Gas Metal Arc Welding Using CO2 Shielding Gas

QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY ◽

10.2207/qjjws.35.103s ◽

2017 ◽

Vol 35 (2) ◽

pp. 103s-107s ◽

Cited By ~ 3

Author(s):

Titinan Methong ◽

Masaya Shigeta ◽

Manabu Tanaka ◽

Rinsei Ikeda ◽

Muneo Matsushita ◽

...

Keyword(s):

Heat Source ◽

Arc Welding ◽

Gas Metal Arc Welding ◽

Shielding Gas ◽

Source Characteristics ◽

Metal Arc Welding

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Risk Analysis of Road Tunnels: A Computational Fluid Dynamic Model for Assessing the Effects of Natural Ventilation

Applied Sciences ◽

10.3390/app11010032 ◽

2020 ◽

Vol 11 (1) ◽

pp. 32

Author(s):

Ciro Caliendo ◽

Gianluca Genovese ◽

Isidoro Russo

Keyword(s):

Natural Ventilation ◽

Fluid Dynamic ◽

Movement Time ◽

Radiant Heat ◽

Heat Fluxes ◽

Maximum Heat ◽

Road Tunnels ◽

Maximum Heat Release ◽

Computational Fluid Dynamics Cfd ◽

Time Required

We have developed an appropriate Computational Fluid Dynamics (CFD) model for assessing the exposure to risk of tunnel users during their evacuation process in the event of fire. The effects on escaping users, which can be caused by fire from different types of vehicles located in various longitudinal positions within a one-way tunnel with natural ventilation only and length less than 1 km are shown. Simulated fires, in terms of maximum Heat Release Rate (HRR) are: 8, 30, 50, and 100 MW for two cars, a bus, and two types of Heavy Goods Vehicles (HGVs), respectively. With reference to environmental conditions (i.e., temperatures, radiant heat fluxes, visibility distances, and CO and CO2 concentrations) along the evacuation path, the results prove that these are always within the limits acceptable for user safety. The exposure to toxic gases and heat also confirms that the tunnel users can safely evacuate. The evacuation time was found to be higher when fire was related to the bus, which is due to a major pre-movement time required for leaving the vehicle. The findings show that mechanical ventilation is not necessary in the case of the tunnel investigated. It is to be emphasized that our modeling might represent a reference in investigating the effects of natural ventilation in tunnels.

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Assessing Heavy Industrial Heat Source Distribution in China Using Real-Time VIIRS Active Fire/Hotspot Data

Sustainability ◽

10.3390/su10124419 ◽

2018 ◽

Vol 10 (12) ◽

pp. 4419 ◽

Cited By ~ 2

Author(s):

Caihong Ma ◽

Jin Yang ◽

Fu Chen ◽

Yan Ma ◽

Jianbo Liu ◽

...

Keyword(s):

Economic Development ◽

Heat Source ◽

Infrared Imaging ◽

Mainland China ◽

Processing System ◽

Source Distribution ◽

Heavy Industry ◽

Rapid Urbanization ◽

Active Fire ◽

Heat Source Distribution

Rapid urbanization and economic development have led to the development of heavy industry and structural re-equalization in mainland China. This has resulted in scattered and disorderly layouts becoming prominent in the region. Furthermore, economic development has exacerbated pressures on regional resources and the environment and has threatened sustainable and coordinated development in the region. The NASA Land Science Investigator Processing System (Land-SIPS) Visible Infrared Imaging Radiometer (VIIRS) 375-m active fire product (VNP14IMG) was selected from the Fire Information for Resource Management System (FIRMS) to study the spatiotemporal patterns of heavy industry development. Furthermore, we employed an improved adaptive K-means algorithm to realize the spatial segmentation of long-order VNP14IMG and constructed heat source objects. Lastly, we used a threshold recognition model to identify heavy industry objects from normal heat source objects. Results suggest that the method is an accurate and effective way to monitor heat sources generated from heavy industry. Moreover, some conclusions about heavy industrial heat source distribution in mainland China at different scales were obtained. Those can be beneficial for policy-makers and heavy industry regulation.

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Effects of heat source distribution on natural convection induced by internal heating

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2004.09.044 ◽

2005 ◽

Vol 48 (6) ◽

pp. 1164-1174 ◽

Cited By ~ 28

Author(s):

Yuji Tasaka ◽

Yasushi Takeda

Keyword(s):

Natural Convection ◽

Heat Source ◽

Source Distribution ◽

Internal Heating ◽

Heat Source Distribution

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Convection in an internally heated stratified heterogeneous reservoir

Journal of Fluid Mechanics ◽

10.1017/jfm.2019.243 ◽

2019 ◽

Vol 870 ◽

pp. 67-105 ◽

Cited By ~ 2

Author(s):

Angela Limare ◽

Claude Jaupart ◽

Edouard Kaminski ◽

Loic Fourel ◽

Cinzia G. Farnetani

Keyword(s):

Heat Source ◽

Scaling Laws ◽

Lower Layer ◽

Thermal Structure ◽

Internal Heat ◽

Source Distribution ◽

Heat Sources ◽

Homogeneous Fluid ◽

Earth’S Mantle ◽

Lower Fluid

The Earth’s mantle is chemically heterogeneous and probably includes primordial material that has not been affected by melting and attendant depletion of heat-producing radioactive elements. One consequence is that mantle internal heat sources are not distributed uniformly. Convection induces mixing, such that the flow pattern, the heat source distribution and the thermal structure are continuously evolving. These phenomena are studied in the laboratory using a novel microwave-based experimental set-up for convection in internally heated systems. We follow the development of convection and mixing in an initially stratified fluid made of two layers with different physical properties and heat source concentrations lying above an adiabatic base. For relevance to the Earth’s mantle, the upper layer is thicker and depleted in heat sources compared to the lower one. The thermal structure tends towards that of a homogeneous fluid with a well-defined time constant that scales with $Ra_{H}^{-1/4}$, where $Ra_{H}$ is the Rayleigh–Roberts number for the homogenized fluid. We identified two convection regimes. In the dome regime, large domes of lower fluid protrude into the upper layer and remain stable for long time intervals. In the stratified regime, cusp-like upwellings develop at the edges of large basins in the lower layer. Due to mixing, the volume of lower fluid decreases to zero over a finite time. Empirical scaling laws for the duration of mixing and for the peak temperature difference between the two fluids are derived and allow extrapolation to planetary mantles.

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