Numerical Simulations of Filling Flows in Die-Casting Molding of the Thin-Walled LED Heat Sink

2014 ◽  
Author(s):  
Rong-Yuan Jou
Keyword(s):  
Computational Model ◽  
Numerical Simulations ◽  
Heat Sink ◽  
Die Casting ◽  
Mold Temperature ◽  
Geometrical Parameters ◽  
Vacuum Die Casting ◽  
Porosity Defects ◽  
Thin Walled ◽  
3D Software

In this study, the mold filling analyses of a thin-walled LED heat sink combined with the vacuum valve runner are simulated by FLOW-3D software. Two topics are analyzed and discussed. First, numerical simulations for variety of molding conditions, including effects of thermal conductivity, vacuum pumping pressure, mold temperature, filling velocity, respectively, are conducted for the computational model of the thin-walled LED heat sink connected with the vacuum shut-off valve. Second, effects of several geometrical parameters, including fin thicknesses of the LED heat sink and dimensions of the vacuum shut-off valve are explored. In these two topics, melts are set to liquid metal of Al 384.0 materials. The first topic of analysis mainly to investigate the effects of molding parameters based upon the same computational model of the thin-walled LED heat sink connected with a vacuum valve runner. The simulated results show if molding conditions are changed, different sizes of defects are appeared in castings; if vacuum pumping pressure is higher, the casting is also firmness, density prone to increase; if vacuum pumping pressure is too low, then pumping efficiency of mold cavity is low and it will be easy to form the casting porosity defects. For the second topic of analysis, molding conditions are hold constantly, and effects of different geometrical dimensions to castings qualifications are simulated. Characteristic dimension of trigger mechanism can effectively operate the vacuum shut-off function; but too thin or too thick of channel, it will affect the pumping time if different degrees of vacuum is imposed. Decreasing of gas residuals in castings for the vacuum pumping pressures of 760Torr, 200Torr, 100Torr compared with 10Torr, were 0.311%, 0.174%, 0.008%, respectively. It shows the appropriate and effective vacuum level for vacuum die-casting of the thin-walled LED heat sink is in the range of 100Torr.

Study on thin walled heat sink of Al-25%Si by die casting

2018 ◽  
Vol 2018.93 (0) ◽  
pp. P018
Author(s):  
Masaru TERAO ◽  
Hiroshi HUSE ◽  
Aiki HAMADA ◽  
Shinjiro Imamura ◽  
Toshio HAGA
Keyword(s):  
Heat Sink ◽  
Die Casting ◽  
Thin Walled

scholarly journals Elliptical Pin Fin Heat Sink: Passive Cooling Control

2021 ◽  
Vol 39 (5) ◽  
pp. 1417-1429
Author(s):  
Fatima Zohra Bakhti ◽  
Mohamed Si-Ameur
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Numerical Simulations ◽  
Heat Sink ◽  
Three Dimensional ◽  
Geometrical Parameters ◽  
Cooling Process ◽  
Pin Fin ◽  
Pin Fins ◽  
And Control

The aim of this study is to examine by means of three-dimensional numerical simulations the thermal-fluid features in elliptical pin fin heat sink. The passive heat transfer enhancement technique is used to comprehend and control the cooling process. This passive methodology is based on pin fins arrangement, hydrodynamic and geometrical parameters. The present numerical results are confronted with experimental measurements in open literature which used one-dimensional model to explore the thermal field. A good agreement was found especially around the optimal fins dimensions. A parametric study has been carried out to deeply analyse the three-dimensional thermal-fluid fields of the heat sink for various key parameters range such the Reynolds number (Re = 50–250) and the aspect ratio (γ=H/d=5.1-9.18). Some new observations and results are obtained thanks to numerical simulations as tool of investigation. It is shown that the fins circumferential temperature is almost uniform. Furthermore, a better cooling is obtained when the Reynolds number increases mainly when the inlet velocity u0> 0.3m/s. The most suitable value of the aspect ratio is attained for γ=8.16, which ensure an optimal cooling process of the pins. A new global Nusselt number correlation was developed for engineering applications.

Towards a More Holistic Approach to Quality Improvements in Aluminium Die Casting

2009 ◽  
Vol 618-619 ◽  
pp. 341-344
Author(s):  
Sandrine Zanna ◽  
Yakov Frayman ◽  
Bruce Gunn ◽  
Saeid Nahavandi
Keyword(s):  
Dynamical System ◽  
System Theory ◽  
Die Casting ◽  
Holistic Approach ◽  
Natural Process ◽  
Dynamical System Theory ◽  
Quality Improvements ◽  
System Perspective ◽  
Porosity Defects ◽  
Natural Equilibrium

This work evaluates the feasibility of using a holistic approach, based on dynamical system theory, to reduce porosity defects in high pressure aluminum die casting. Quality improvements, from a dynamical system perspective mean the ability to move the die casting process out of its natural equilibrium to a more beneficial state and the ability to maintain this new process state. This more beneficial state may be achieved in several ways. One way is to increase the amount of forcing to overcome natural process resistance. This forcing approach is represented by typical continuous intervention policy, with modifications in die/part design and/or process parameters. An alternative approach is to reduce the amount of natural process resistance, in particular the amount of process disturbance, allowing the process to move out of its natural equilibrium with much less forcing. This alternative uses the self-regulating ability of dynamical systems thus decreasing the amount of human intervention required. In this respect, the influence of vacuum on time on chattering at the first stage of the casting shot was identified as a good process candidate for testing using dynamical system theory. A significant reduction in porosity defects was achieved, which also set the process on a path of slow but consistent self-improvement.

scholarly journals Mathematical modeling and numerical simulation of heat dissipation in led bulbs

2020 ◽  
Vol 24 (3 Part A) ◽  
pp. 1877-1884 ◽  
Author(s):  
Diego Alarcón ◽  
Eduardo. Balvís ◽  
Ricardo Bendaña ◽  
Alberto Conejero ◽  
de Fernández ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Numerical Simulation ◽  
Numerical Simulations ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Thermal Contact ◽  
Heat Sinks ◽  
Experimental Measurements ◽  
Heating And Cooling ◽  
The Common

We present a detailed study of heating and cooling processes in LED luminaires with passive heat sinks. Our analysis is supported by numerical simulations as well as experimental measurements, carried on commercial systems used for outdoor lighting. We have focused our analysis on the common case of a single LED source in thermal contact with an aluminum passive heat sink, obtaining an excellent agreement with experimental measurements and the numerical simulations performed. Our results can be easily expanded, without loss of generality, to similar systems.

scholarly journals INFLUENCE OF CREEP CONCRETE ON SPACE STABILITY THIN-WALLED DOME COVERINGS

2021 ◽  
Vol 1 (24) ◽  
Author(s):  
Ekaterina Prokshits ◽  
Sergey Gridnev ◽  
Olga Sotnikova ◽  
Iana Zolotukhina
Keyword(s):  
Theory Of Elasticity ◽  
Deformation Condition ◽  
Software Systems ◽  
Geometrical Parameters ◽  
Loss Of Stability ◽  
Construction Mechanics ◽  
Body Construction ◽  
Calculation Results ◽  
Load Action ◽  
Thin Walled

The task was set, due to the capabilities of modern software systems, to assess the effect of the increase in inelastic deformations under prolonged load action on the loss of stability of thin-walled dome coverings. The study of the dependences of the forms of the loss of stability of dome covering from creep concrete that will help further with optimization calculations when determining of the most influencing parameters of designs. Calculation results of thin-walled concrete dome roof of circular outline under the influence of operational loadings with use of two modern program complexes are given in article. It is investigated intense and deformation condition of dome coverings as a part of construction from position of forecasting of possible forms of loss of stability, with use of opportunities of the final and element «MidasCivil» computer system. In work provisions of the theory of elasticity, mechanics of deformation of solid body, construction mechanics and also methods of mathematical modeling based on application of finite element method are used. The received results give the chance to rationally select geometrical parameters and material of design and also to set structural strength safety factors at the solution of problems of stability of different covers taking into account possible creep of material.

Study on Local Extrusions' Effects on Improvement of Die Casting Prismatic Parts' Forming Quality

2013 ◽  
Vol 312 ◽  
pp. 475-479
Author(s):  
Wei Gang Zheng ◽  
Cun Hong Yin ◽  
Yu Hong Yuan ◽  
Zhen Min Pan ◽  
Chao Tang
Keyword(s):  
Mechanical Properties ◽  
Die Casting ◽  
Casting Process ◽  
Extrusion Process ◽  
Shrinkage Porosity ◽  
Shrinkage Cavity ◽  
Prismatic Parts ◽  
Porosity Defects ◽  
Die Casting Process ◽  
Casting Production

This paper analyzes traditional die casting process to find out the reasons that cause shrinkage cavity and porosity defects in casting. An optimized process of die casting by using local extrusion is proposed. A device used in local extrusion which realizes forcing compensating contraction on key parts of crankcase is designed and the parameters of local extrusion process are discussed. Compared the mechanical properties and microstructure of local extrusion used in die casting production with traditional. It shows that local extrusion used in die casting production can not only achieve the aim eliminating shrinkage porosity and cavity of a casting but also can refine grain to improve the mechanical properties.

Numerical Simulation of Casting Deformation and Stress of A356 Aluminum Alloy Thin-Walled Frame Casting

2021 ◽  
Vol 1033 ◽  
pp. 24-30
Author(s):  
Yi Dan Zeng ◽  
Li Tong He ◽  
Jin Zhang
Keyword(s):  
Aluminum Alloy ◽  
Casting Process ◽  
Mold Temperature ◽  
Hot Cracking ◽  
Thin Wall ◽  
A356 Aluminum Alloy ◽  
Pouring Temperature ◽  
Thin Walled ◽  
Alloy Castings ◽  
A356 Aluminum

One of the main reasons for the scrap of cast thin-wall frame aluminum alloy castings is deformation and cracking. It is an effective method for solving the problem by predicting the distribution of casting stress, clarifying the size of the deformation and the location of the crack, and taking necessary measures in the process. This paper uses the ProCAST software to simulate the thermal stress coupling of A356 thin-walled frame castings, analyzes the influence of pouring temperature, pouring speed and mold temperature on the stress field distribution of castings, predicts the hot cracking trend and deformation, and optimizes Casting process..

Thermally Optimum Natural Convection Cooled Longitudinal-Plate Heat Sinks With Horizontal Base Plates

2001 ◽  
Author(s):  
K. K. Sikka ◽  
C. George
Keyword(s):  
Natural Convection ◽  
Heat Sink ◽  
Base Plate ◽  
Heat Sinks ◽  
Geometrical Parameters ◽  
Plate Heat ◽  
Horizontal Orientation ◽  
Fin Spacing ◽  
Base Plates ◽  
Weakly Dependent

Abstract Longitudinal-plate fin heat sinks are optimized under natural convection conditions for the horizontal orientation of the heat sink base plate. The thermal performance of the heat sinks is numerically modeled. The fin height, thickness and spacing and heat sink width are systematically varied. The numerical results are validated by experimentation. Results show that the thermal resistance of a heat sink minimizes for a certain number of fins on the base plate. The fin spacing-to-length ratio at which the minimum occurs is weakly dependent on the fin height and thickness and heat sink width. The flow fields reveal that the minimum occurs for the heat sink geometry in which the number of fins are maximized such that the flow velocity as the air exits the fins is fully developed. A correlation of the heat transfer with the heat sink geometrical parameters is also developed.

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