Mathematical Approaching and Experimental Assembly to Evaluate the Risks of In-Service Welding in Hot Tapping

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Ivo Andrei de O. L Lima ◽  
Alex Alisson Bandeira Santos
Keyword(s):  
Mathematical Model ◽  
Heat Source ◽  
Arc Welding ◽  
Numerical Models ◽  
Temperature Fields ◽  
Physical Situation ◽  
Rectilinear Motion ◽  
Heat Sources ◽  
The Mathematical Model ◽  
Burn Through

The welding onto in-service pipeline (operation condition) results in three possibilities of high risks: leaking and/or explosion by burn-through, chemical reactions to instability, or even explosion due to the heat on internal fluid and cracking in heat affected zone (HAZ). The numerical methods have a useful role in the assessment of welding conditions for the safe in-service welding of pipelines. Only limited published works have considered direct calculation of burn-through using a combination of thermal and stress analysis. The mathematical model of the heat source is the most important part of these numerical models, and actually the mathematical model which described better the heat distribution of the arc welding through gas-shielded tungsten arc welding (GTAW) process or shielded metal arc welding process is the double ellipsoidal heat source (DEHS) model of Goldak and Akhlaghi (2010, Computational Welding Mechanics, Springer Books, New York, pp. 32–35). However, that model has considered the heat source in rectilinear motion only, and it depends on three parameters (a, b, c) which are related with the weld bead size and shape to define the geometry and co-ordinates of heat source, and they are determined empirically or experimentally. Few researchers published works that could determine these parameters mathematically, from the welding data. The publication that best analytically addressed this issue was the work of Eagar and Tsai (1983, “Temperature Fields Produced by Traveling Distributed Heat Sources,” Weld. J., 62(12), pp. 346–355). First, this paper presents a new equation for heat source in double ellipsoid considering the circular motion, trying to develop a model closer to the physical situation of hot tapping onto pipeline. Second, a proposal for determination of the parameters a, b analytically from the Eagar model and Tsai (1983, “Temperature Fields Produced by Traveling Distributed Heat Sources,” Weld. J., 62(12), pp. 346–355), and third, an experimental facility to get the temperature field that was used to validate the numerical finite element models.

Development of Convective Heat Transfer Near Suddenly Heated, Vertically Aligned Horizontal Wires

1987 ◽  
Vol 109 (4) ◽  
pp. 912-918 ◽  
Author(s):  
J. R. Parsons ◽  
M. L. Arey
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Fluid Layer ◽  
Convective Motion ◽  
Transient Behavior ◽  
Temperature Fields ◽  
Heat Sources ◽  
Transfer Coefficients ◽  
Vertically Aligned ◽  
The Wire

Experiments have been performed which describe the transient development of natural convective flow from both a single and two vertically aligned horizontal cylindrical heat sources. The temperature of the wire heat sources was monitored with a resistance bridge arrangement while the development of the flow field was observed optically with a Mach–Zehnder interferometer. Results for the single wire show that after an initial regime where the wire temperature follows pure conductive response to a motionless fluid, two types of fluid motion will begin. The first is characterized as a local buoyancy, wherein the heated fluid adjacent to the wire begins to rise. The second is the onset of global convective motion, this being governed by the thermal stability of the fluid layer immediately above the cylinder. The interaction of these two motions is dependent on the heating rate and relative heat capacities of the cylinder and fluid, and governs whether the temperature response will exceed the steady value during the transient (overshoot). The two heat source experiments show that the merging of the two developing temperature fields is hydrodynamically stabilizing and thermally insulating. For small spacing-to-diameter ratios, the development of convective motion is delayed and the heat transfer coefficients degraded by the proximity of another heat source. For larger spacings, the transient behavior approaches that of a single isolated cylinder.

Analytical Formulation for the Temperature Profile by Duhamel’s Theorem in Bodies Subjected to an Oscillatory Heat Source

2005 ◽  
Vol 129 (2) ◽  
pp. 236-240 ◽  
Author(s):  
Jun Wen ◽  
M. M. Khonsari
Keyword(s):  
Finite Element Method ◽  
Heat Flux ◽  
Heat Source ◽  
Temperature Profile ◽  
Rectangular Domain ◽  
Temperature Fields ◽  
Heat Sources ◽  
Point Heat Source ◽  
Analytical Formulation ◽  
Analytical Technique

An analytical technique is presented for treating heat conduction problems involving a body experiencing oscillating heat flux on its boundary. The boundary heat flux is treated as a combination of many point heat sources, each of which emits heat intermittently based on the motion of the flux. The working function of the intermittent heat source with respect to time is evaluated by using the Fourier series and temperature profile of each point heat source is derived by using the Duhamel’s theorem. Finally, by superposition of the temperature fields over all the point heat sources, the temperature profile due to the original moving heat flux is determined. Prediction results and verification using finite element method are presented for an oscillatory heat flux in a rectangular domain.

The Numerical Simulation of the Solar-Air Dual-Source Heat Pump System

2011 ◽  
Vol 138-139 ◽  
pp. 305-309
Author(s):  
Chao Zhang ◽  
Xiao Dan Zhao ◽  
Guang Hui Zhou
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Heat Pump ◽  
Parameter Method ◽  
Heat Sources ◽  
The Novel ◽  
Pump System ◽  
Heat Pump System ◽  
Dual Source ◽  
The Mathematical Model

The heat pump technology which is as an effective energy-saving technology has attracted more and more attentions. A novel solar-air dual-source heat pump system which could synchronously use two heat sources has been provided. In this paper, the mathematical model of the new heat pump system has been built and the calculation accuracy of the mathematical model has been proved. Based on a novel solar-air dual-source heat pump system, the mathematical models of the thermophysical parameters of working fluids, compressor, capillary, condenser, evaporator, and heat pump system have been established. The distribution parameter method has been adopted in the mathematical models of condenser and evaporator. Three operation modes of the novel solar-air dual-source heat pump system have been simulated. The simulated results and the experimental results have been compared. The experiments of the novel solar-air dual-source heat pump system have been accomplished in the constant temperature and humidity laboratory. The compared results show that the error is less than 10%.

The study of the temperature field in an infinite slab under line and plane heat source

2015 ◽  
Vol 25 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Wang Qing-Cheng ◽  
Wu Zhao-Chun ◽  
Zhu Xiang-Ping
Keyword(s):  
Temperature Field ◽  
Heat Source ◽  
Temperature Rise ◽  
Temperature Fields ◽  
Manufacturing Processes ◽  
Heat Sources ◽  
Content Type ◽  
Infinite Slab ◽  
Different Types ◽  
Changing Patterns

Purpose – The purpose of this paper is to reveal the characteristics of the temperature field under different types of heat sources, which are significant to the temperature control encountered in practical manufacturing processes. Design/methodology/approach – The temperature fields in an infinite slab under line or plane heat source are calculated numerically by control volume approach and ADI scheme, and the numerical results of the temperature rise have been compared among the different types of the heat sources. Findings – The numerical results show the different changing patterns of temperature fields under line and plane heat source, respectively, and demonstrate that the magnitude of temperature rise depends strongly on the type of the heat sources. The order of temperature rise from high to low is point, line and plane heat source base on the same input heat. Originality/value – The study is original and findings are new, which demonstrate the different changing patterns of temperature fields and the magnitude of temperature rise under line and plane heat source. The numerical solution is significant for the temperature control in practical manufacturing processes.

Study on Mathematical Model of Temperature Field in the Laser Welding Process

2010 ◽  
Vol 426-427 ◽  
pp. 89-92
Author(s):  
Hong Feng Wang ◽  
Dun Wen Zuo ◽  
Ming Min Huang ◽  
Hong Miao
Keyword(s):  
Mathematical Model ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Heat Source ◽  
Laser Welding ◽  
Welding Process ◽  
Actual Process ◽  
Analytical Results ◽  
The Mathematical Model ◽  
Laser Welding Process

From the laser welding actual process, the welding heat source model of laser welding process was established, that is, superposition heat source. According to the knowledge of thermodynamics, the establishment of a welding process, the mathematical model of temperature distribution of laser welding process was obtained by laser welding heat source. Finally, the finite element simulation of welding temperature distribution was used. The simulated results were compared with the analytical results of mathematical model of temperature field, it was proved consistent between simulated results and analytical results, at the same time it can account for the correctness of the mathematical model of temperature field.

Validation of the Mathematical and Numerical Models for Artillery Barrels Autofrettage Based on Hydrostatic Procedure

2012 ◽  
Vol 186 ◽  
pp. 58-69
Author(s):  
Ghiţă Bârsan ◽  
Silviu Mihai Petrişor ◽  
Luminiţa Giurgiu
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Numerical Models ◽  
Experimental Tests ◽  
Tension Test ◽  
Advanced Materials ◽  
New Materials ◽  
New Techniques ◽  
The Military ◽  
The Mathematical Model

The research of advanced gun barrels focuses on materials or the combination between advanced materials and new innovative processes that enable the increase of the life cycle and performances of all calibers cannons. In addition to the investigation of new materials, considerable efforts were made for developing new techniques. The paper describes a theoretical framework validated with the experimental tests for increasing mechanical properties of thick-walled tubes subjected to high interior pressure loads. The theoretical model established a mathematical model of calculus for non-linear environments in the case of self-hooping or autofrettaging of the thick-walled tubes. The mathematical model was validated with experimental tests performed in the Mechanical Engineering Laboratory of the Military Technical Academy in Bucharest on a standard tension test specimens collected from the abutment barrel made out of alloyed steel. Finally, the present paper introduces some theoretical guidelines of hydrostatic procedure in the field of artillery barrels manufacturing, as well as experimental data obtained after using the autofrettage procedure.

scholarly journals Experience in modeling a comfortable environment in the transport compartment

2020 ◽  
Vol 157 ◽  
pp. 01019
Author(s):  
Vladimir Pankratov ◽  
Alexey Golikov ◽  
Elena Pankratova ◽  
Marina Barulina ◽  
Sofiya Galkina
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Temperature Fields ◽  
Thermal Processes ◽  
Passenger Compartment ◽  
The Public ◽  
Actual Operating ◽  
Specific Proposal ◽  
Series Of Experiments ◽  
The Mathematical Model

The theoretical base was developed and the mathematical model of dynamic thermal processes in a compartment of public transport was constructed. The software which is realized the constructed mathematical model was developed. The mathematical model provides for the possibility of taking into account the most possible environmental conditions which can have place in the actual operating conditions of a transport even the angle of illumination - the current temperature of the external environment, the presence of solar radiation taking into account the angle of sun’s illumination, and the temperature of the roadway. The software allows calculation and visualization non –stationary temperature fields in the public transport’s compartments using the example of a trolley bus. For a specific trolley bus design, a series of experiments to calculate the comfortable temperature for passengers were conducted, These experiments are showed the performance of the constructed model and allowed to formulate a specific proposal for improving the thermoregulation system of the trolleybus’ passenger compartment.

scholarly journals Сorrection сalculation of the heat source power during plasma-powder surfacing of the necks of stepped shafts

2019 ◽  
Vol 298 ◽  
pp. 00123
Author(s):  
G.R. Latypova ◽  
N.N. Karpenko ◽  
R.A. Latypov
Keyword(s):  
Mathematical Model ◽  
Heat Source ◽  
Heat Equation ◽  
Penetration Depth ◽  
Calculation Method ◽  
Temperature Fields ◽  
Lambert Function ◽  
Practical Application ◽  
Differential Heat ◽  
Source Power

A mathematical model is proposed for calculating temperature fields during arc surfacing of limited cylinders, eliminating the need for dimensionless parameters, when solving the differential heat equation, which facilitates the practical application of the developed calculation method. It is proposed that the penetration depth be calculated using the Lambert function. The obtained dependences make it possible to quantify the required correction of the heat source power in the process of surfacing the necks of stepped shafts.

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