Effect of Thermal Contact Resistance on Alumina Molten Particle Impacting onto a Metal Substrate

In this paper, a Finite Element Analysis is carried out in order to simulate the process of spreading and solidification of a micrometric molten droplet impinging onto a cold substrate. This process is a crucial key to have a good understanding of coatings obtained by means of thermal spraying. The effect of thermal contact resistance (TCR) on the droplet spreading and solidification was investigated using different values of TCR and different droplet sizes. The solidification time was found to be a linear function of the droplet diameter square. Viscous dissipation, wettability and surface tension effects are taken into account. The Level Set method was employed to explicitly track the free surface of molten droplets.

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Numerical Study on Substrate Remelting, Flow, and Resolidification in Microcasting

Volume 3 ◽

10.1115/ht-fed2004-56621 ◽

2004 ◽

Author(s):

F. J. Hong ◽

H.-H. Qiu

Keyword(s):

Contact Resistance ◽

Thermal Contact Resistance ◽

Numerical Study ◽

Thermal Contact ◽

Spreading Factor ◽

Droplet Spreading ◽

Molten Droplet ◽

Front Shape ◽

Complex Fluid

A large and highly superheated molten droplet impacting onto the substrate during the microcasting was studied numerically. In this study, same material for both the droplet and the substrate was considered. Numerical model including the complex fluid dynamics of droplet, interfacial thermal contact resistance, and substrate remelting, as well as the flow in the substrate has been developed. Numerical simulations of a microcasting experiment were conducted with the different thermal contact resistances. The results of simulations show that the spreading factor and substrate remelting agreed well with the experimental data under the assumption of an appropriate thermal contact resistance. It is also found that the thermal contact resistance plays an important role not only in droplet spreading arrest but also in the determination of substrate remelting volume and remelting front shape. The effects of droplet impacting velocity, superheat and substrate temperature were also investigated.

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Deformation and Solidification of Droplet Impact With Variable Thermal Contact Resistance

Heat Transfer: Volume 3 ◽

10.1115/ht2003-47056 ◽

2003 ◽

Cited By ~ 2

Author(s):

W. Wang ◽

H.-H. Qiu ◽

P. Cheng

Keyword(s):

Numerical Simulation ◽

Contact Resistance ◽

Thermal Contact Resistance ◽

Thermal Contact ◽

Solidification Process ◽

Numerical Results ◽

Thermal Contact Conductance ◽

Contact Conductance ◽

Molten Droplet ◽

Comparison Results

Interfacial thermal contact resistance between the impinging flow of a molten droplet and a substrate, which is qualified by thermal contact conductance, plays an important role in the spreading and solidification of a droplet. In the present study, a simple correlation for the thermal contact conductance in the rapid contact solidification process was developed. With this correlation being directly used in numerical simulation, for the first time, a variable thermal contact resistance was taken into consideration to simulate both the dynamics and phase change responses during a molten droplet impingement. Numerical results were compared with that of the cases when thermal contact resistance was zero or a constant. The changes in spread factor with time and thermal contact conductance indicated that predictions from the computer simulation were sensitive to the values of thermal contact resistance. Experiment was conducted to demonstrate the validity of the present study. Comparison results showed that rather than using a constant average value, better agreement between the experimental and numerical results would be obtained if a variable thermal contact resistance were used in the numerical simulation.

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The Testing and Finite Element Analysis of Temperature Distribution and Thermal Deformation in Vertical Machining Center

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.538-541.730 ◽

2012 ◽

Vol 538-541 ◽

pp. 730-734

Author(s):

Bing Fang ◽

Lei Zhang ◽

Jian Fu Zhang ◽

Ya Hong Li

Keyword(s):

Temperature Distribution ◽

Contact Resistance ◽

Thermal Deformation ◽

Thermal Contact Resistance ◽

Thermal Contact ◽

Measuring Method ◽

Temperature Fields ◽

Element Analysis ◽

Fea Model ◽

Machining Center

This paper presented a real-time measuring method of temperature fields and thermal deformations in vertical machining center. And a FEA model including the thermal contact resistance at interface for evaluating the temperature distribution and tools deformation in vertical machining center (VMC) was established. Compared with the experiment results, it is shown that the new model is much more accurate than the traditional model without considering thermal contact resistance at interface.

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