Fluid flow in casting rigging systems: Modeling, validation, and optimal design

McDavid, Robert M.; Dantzig, Jonathan A.

doi:10.1007/s11663-998-0103-1

Cited by 17 publications

(5 citation statements)

References 29 publications

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“…[1,2] The physicochemical aspects of filtration, including the surface tension properties of the phases involved and the filter structure, were addressed by various researchers. [3][4][5] The application of ceramic filters to the continuous casting of steel was also proposed, [6,7] but the length of the casting cycles rendered filters useless, either because of clogging or excessive wear or both.…”

Section: Literature Reviewmentioning

confidence: 99%

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Simulation of Fluid and Inclusions Dynamics during Filtration Operations of Ductile Iron Melts Using Foam Filters

Dávila-Maldonado

Adams²,

Oliveira

et al. 2008

Metall Mater Trans B

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The use of ceramic foam filters in ductile iron foundries to reduce the number of inclusions that reach the casting has been widely accepted. However, the exact mechanisms contributing to foam filter effectiveness are not yet known; this limits the ability to maximize filter performance and inclusion reduction. The objective of this work is to qualify and quantify the effects of the foam filter structure on inclusion retention. This has been accomplished through the development of a three-dimensional (3-D) mathematical model, based on physical water modeling and mathematical simulations. It was found that the casting rate and inclusion density play minor roles in the capture ratio, while inclusion size is the most influent variable. One mechanism for capturing inclusions involves the direct impact of an inclusion on the web wall and its adhesion after crossing over the liquid film. Two additional mechanisms involve the entrainment of inclusions by buoyancy-lift forces into low-velocity fields and the ulterior adhesion through buoyancy effects. The second mechanism is the entrainment of inclusions into microrecirculating flows; the inclusions remain in these flows for times that exceed the mold filling time. The latter mechanism has limited intensity for inclusions approximately 30 to 100 lm in size. In order to enhance the effects of this mechanism in this range of sizes, the vorticity magnitude in the microfree shear flows in the filter's pores must be increased, through changes in the structure geometry of this device.

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Section: Literature Reviewmentioning

confidence: 99%

“…Equations [5], [6], and [10] are substituted in Eq. [3], to calculate the velocity vector of an inclusion; the result is used in Eq.…”

Section: Mathematical Modelmentioning

confidence: 99%

Simulation of Fluid and Inclusions Dynamics during Filtration Operations of Ductile Iron Melts Using Foam Filters

Dávila-Maldonado

Adams²,

Oliveira

et al. 2008

Metall Mater Trans B

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“…Physical experiments have also been performed to evaluate the applicability of the mixing length model to casting-mold filling flows, and to evaluate the success of the optimal design. The results of these experiments are presented in a separate publication [42].…”

Section: Example Applicationmentioning

confidence: 99%

Design sensitivity and finite element analysis of free surface flows with application to optimal design of casting rigging systems

McDavid

Dantzig

1998

Int. J. Numer. Meth. Fluids

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A novel, fully‐analytical design sensitivity formulation for transient, turbulent, free surface flows is derived and implemented in the context of finite element analysis. The time‐averaged, turbulent form of the Navier–Stokes equations are solved using a mixing length model, in conjunction with the volume of fluid (VOF) method to model the free surface movement. The design derivatives of these governing equations are computed and solved to find the analytical sensitivities of the fluid position, velocity and pressure fields with respect to shape design variables. The computational efficiency produced by evaluating the sensitivities analytically is demonstrated. The design of the runner and gating system of a simple block casting is presented as an example application for using sensitivity information in design. The analytical sensitivity routine is coupled to a numerical optimizer to yield an automated method for optimal design of the casting rigging system. The results produce runner shapes which eliminate mold‐gas aspiration. © 1998 John Wiley & Sons, Ltd.

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“…Alternative methods such as computational modeling and water analogue techniques (physical modeling) have been investigated and utilized in both the foundry industry and academia to characterize the conditions present during filling of the die, such as fluid velocities and fill profiles. This information has in turn been used for optimization of the casting process [11,12,13] This chapter reviews the information reported in literature that is focused on aluminum oxide films, the defects caused by oxide films, the entrainment processes, computational modeling of die filling and the utilization of the water analogs to study the metal casting.…”

Section: Literature Reviewmentioning

confidence: 99%

“…Water models can be used as a simple means to validate mathematical mode ls, owing to its advantages in flow observation and measurement. Both qualitative comparison, by flow patterns, and quantitative comparison, by filling rate assessments, can be carried out with relatively inexpensive equipment [12]. Once validated, the mathematical model can be applied to simulate aluminum filling with confidence.…”

Section: Water Analogue Technique (Physical Model)mentioning

confidence: 99%

Physical and Computational Models of Free Surface Related Defects in Low‐Pressure Die‐Cast Aluminum Alloy Wheels

et al. 2011

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The difference of die filling, which can be characterized by the free surface flow behavior, has a strong influence on the quality of casting components. In the case of cast aluminum alloy wheels, an undesired filling pattern with excessive turbulence can cause portions of the surface oxide film to be entrained within the bulk liquid resulting in defects such as cosmetic paint-pops, hot tears, porosity and rim-leaks.To investigate the influence of die filling on defect formation in low-pressure die-cast aluminum wheels, a water analogue physical model was built, instrumented and tested to simulate the free surface behavior during die filling of a low-pressure die-cast (LPDC) wheel. The physical model contains a transparent planar die section which was manufactured out of the geometry of a production die, and an automatic pressure control system that achieves liquid feeding conditions similar to the industrial process. A set of die filling tests with different venting conditions was carried out to explore the role of venting on the free surface behavior of water and to produce data for validation of a computational model. The computational model was developed, based on the commercial computational fluid dynamics code ANSYS CFX, for the purposes of predicting the flow conditions during die filling, providing qualitative a nd quantitative flow information that are otherwise not possible to obtain through experimental measurement, and identifying key features that influences the flow during die filling at a lower cost of time and labor.Comparison between the experimental and numerical data has shown that the computational model was able to qualitatively reproduce the flow behavior observed in the water model in the conditions tested. Both the experimental and the model results indicate that the entrainment of surface oxide films and air bubbles could occur at the outboard rim flange during the filling of the flange, below the free surface of the returning waves in the spoke and at the junction of the iii hub and the spoke during the filling of the hub. In both cases, venting conditions have been proved crucial and the importance of vent design in commercial die design was highlighted.iv

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Fluid flow in casting rigging systems: Modeling, validation, and optimal design

Cited by 17 publications

References 29 publications

Simulation of Fluid and Inclusions Dynamics during Filtration Operations of Ductile Iron Melts Using Foam Filters

Simulation of Fluid and Inclusions Dynamics during Filtration Operations of Ductile Iron Melts Using Foam Filters

Design sensitivity and finite element analysis of free surface flows with application to optimal design of casting rigging systems

Physical and Computational Models of Free Surface Related Defects in Low‐Pressure Die‐Cast Aluminum Alloy Wheels

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