Estimation of heat flux at metal-mold interface during solidification of cylindrical casting

2012 ◽  
Vol 6 (4) ◽  
pp. 453-458 ◽  
Author(s):  
L. Q. Zhang ◽  
R. J. Wang
Keyword(s):  
Heat Flux ◽  
Metal Mold ◽  
Cylindrical Casting

Effect of Mold Filling on the Formation of Air Gap Along the Vertical Mold Wall During Solidification of Al-Cu Alloy

2007 ◽  
Author(s):  
S. Arunkumar ◽  
K. V. Sreenivas Rao ◽  
T. S. Prasanna Kumar
Keyword(s):  
Heat Flux ◽  
Spatial Variation ◽  
Mold Wall ◽  
Heat Conduction Problem ◽  
Research Work ◽  
Mold Filling ◽  
Inverse Heat Conduction Problem ◽  
Air Gap ◽  
Heat Fluxes ◽  
Metal Mold

The accuracy of the numerical simulation of casting solidification largely depends on the selection of appropriate thermal boundary conditions. The estimation of heat flux at the metal-mold interface becomes difficult due to the formation of spatially and temporally varying air gap in gravity die-casting. However, the spatial variation in the formation of air gap is often neglected in most of the previous research work. In this paper, an experimental setup that involved mold filling was devised In order to study the spatial variation of air gap and its effect on the heat flux at the metal-mold interface. A Serial-IHCP (inverse heat conduction problem) algorithm was used to estimate the multiple heat flux transients along the metal-mold interface. The estimated heat fluxes at the metal-mold interface have considerable variation during the initial stages of solidification. Further, the analysis indicates that the non-conformal contact between metal and mold begins at the bottom. However, the formation of clearance gap at the metal-mold interface follows a reverse trend as it starts from the top of the vertical mold wall and progresses towards the bottom.

Determination of Multiple Heat Flux at the Metal-Mold Interface during Casting Solidification

2012 ◽  
Vol 557-559 ◽  
pp. 1251-1256
Author(s):  
Li Qiang Zhang ◽  
Rong Ji Wang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Spatial Variation ◽  
Solidification Process ◽  
Metal Mold ◽  
Gap Formation ◽  
Conduction Model ◽  
Flux Boundary Condition ◽  
Proposed Model

For successful modeling of the solidification process, a reliable heat flux boundary condition is required. Many research works has contributed to understand the mechanism of heat transfer and to quantify the heat flux at the metal-mold interface. However, for ease of calculation, the metal-mold heat transfer is often assumed to be uniform and no spatial variation in the air gap formation among these researches. In this paper, a two-dimensional inverse conduction model is introduced. The proposed model can be used to calculate the heat flux with spatial variation. The accuracy and stability of the model has been investigated by a typical profile of heat flux simulating practical conditions of casting solidification. Meanwhile, the effects of various calculation parameters in the inverse algorithm have been also analyzed. The analyzed results show that the proposed inverse model is a feasible and effective tool for determination of the metal-mold interface heat flux.

Inverse Estimation for Heat Flux Distribution at the Metal-Mold Interface Using Fuzzy Inference

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
Lina Zhu ◽  
Guangjun Wang ◽  
Hong Chen ◽  
Zhaoming Luo
Keyword(s):  
Heat Flux ◽  
Measurement Errors ◽  
Flux Distribution ◽  
Fuzzy Inference ◽  
Casting Process ◽  
Metal Mold ◽  
Heat Flux Distribution ◽  
Inverse Approach ◽  
Ill Posed ◽  
Measured Information

This study provides a new inverse approach based on fuzzy inference for solving the problem of estimating heat flux distribution at the metal-mold interface in the continuous casting process. Measured temperatures acquired with the thermocouples buried in the mold are used to obtain corresponding inference results with the fuzzy inference. Then according to the importance of measured information for estimating the heat flux distribution, inference results are weighted to realize estimation of heat flux distribution at the metal-mold interface. Some numerical tests are presented to discuss the validity of the present approach by using different initial guesses of heat flux distribution, the number of measuring points, and measurement errors. In comparison with the conjugate gradient method, it is concluded that the method based on fuzzy inference is of a good anti-ill-posed characteristic.

Siphon Flows in Stratified Coronal Loops

1994 ◽  
Vol 144 ◽  
pp. 185-187
Author(s):  
S. Orlando ◽  
G. Peres ◽  
S. Serio
Keyword(s):  
Heat Flux ◽  
Scaling Laws ◽  
Flow Model ◽  
Supersonic Flows ◽  
Coronal Loops ◽  
Characteristic Parameters

AbstractWe have developed a detailed siphon flow model for coronal loops. We find scaling laws relating the characteristic parameters of the loop, explore systematically the space of solutions and show that supersonic flows are impossible for realistic values of heat flux at the base of the upflowing leg.

Rate of Sublimation of Ice by Radiative Heating in Freeze-Etching

1980 ◽  
Vol 38 ◽  
pp. 618-619
Author(s):  
Yeshayahu Talmon
Keyword(s):  
Heat Flux ◽  
Freeze Fracture ◽  
Constant Heat Flux ◽  
Radiative Heating ◽  
Constant Heat ◽  
Entire Sample ◽  
Simplified Method ◽  
Freeze Etching ◽  
Sublimation Rates ◽  
Fractured Surface

To bring out details in the fractured surface of a frozen sample in the freeze fracture/freeze-etch technique,the sample or part of it is warmed to enhance water sublimation.One way to do this is to raise the temperature of the entire sample to about -100°C to -90°C. In this case sublimation rates can be calculated by using plots such as Fig.1 (Talmon and Thomas),or by simplified formulae such as that given by Menold and Liittge. To achieve higher rates of sublimation without heating the entire sample a radiative heater can be used (Echlin et al.). In the present paper a simplified method for the calculation of the rates of sublimation under a constant heat flux F [W/m2] at the surface of the sample from a heater placed directly above the sample is described.

Numerical analysis of local heat flux and thin-slab solidification in a CSP funnel-type mold with electromagnetic braking

2020 ◽  
Vol 117 (6) ◽  
pp. 602
Author(s):  
Heping Liu ◽  
Jianjun Zhang ◽  
Hongbiao Tao ◽  
Hui Zhang
Keyword(s):  
Heat Flux ◽  
Casting Speed ◽  
Shell Growth ◽  
Local Heat ◽  
Operating Conditions ◽  
Thin Slab ◽  
Wide Face ◽  
Slab Width ◽  
Steel Grades ◽  
Local Heat Flux

In this article, based on the actual monitored temperature data from mold copper plate with a dense thermocouple layout and the measured magnetic flux density values in a CSP thin-slab mold, the local heat flux and thin-slab solidification features in the funnel-type mold with electromagnetic braking are analyzed. The differences of local heat flux, fluid flow and solidified shell growth features between two steel grades of Q235B with carbon content of 0.19%C and DC01 of 0.03%C under varying operation conditions are discussed. The results show the maximum transverse local heat flux is near the meniscus region of over 0.3 m away from the center of the wide face, which corresponds to the upper flow circulation and the large turbulent kinetic energy in a CSP funnel-type mold. The increased slab width and low casting speed can reduce the fluctuation of the transverse local heat flux near the meniscus. There is a decreased transverse local heat flux in the center of the wide face after the solidified shell is pulled through the transition zone from the funnel-curve to the parallel-cure zone. In order to achieve similar metallurgical effects, the braking strength should increase with the increase of casting speed and slab width. Using the strong EMBr field in a lower casting speed might reverse the desired effects. There exist some differences of solidified shell thinning features for different steel grades in the range of the funnel opening region under the measured operating conditions, which may affect the optimization of the casting process in a CSP caster.

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