scholarly journals Rapid Numerical Estimation of Pressure Drop in Hot Runner System

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 207
Author(s):  
Jae Sung Jung ◽  
Sun Kyoung Kim
Keyword(s):  
Pressure Drop ◽  
Injection Molding ◽  
Steady Flow ◽  
Design Process ◽  
Newtonian Fluid ◽  
Numerical Estimation ◽  
Generalized Newtonian Fluid ◽  
Computer Tool ◽  
Pressure Drops ◽  
Runner Design

To determine dimensions in the hot runner systems, given a material, it is necessary to predict the pressure drop according to them. Although modern injection molding simulators are able to evaluate such pressure drops, they are expensive and demanding to be employed as a design utility. This work develops a computer tool that can calculate a pressure drop from the sprue to the gate assuming a steady flow of a generalized Newtonian fluid. For a four drop hot runner system, the accuracy has been verified by comparing the obtained results with those by a commercial simulator. This paper presents how to utilize the proposed method in the hot runner design process.

Analysis of Viscoelastic Flows Through Converging-Diverging Channels

2004 ◽  
Author(s):  
Mauricio Lane ◽  
Moˆnica F. Naccache ◽  
Paulo R. Souza Mendes
Keyword(s):  
Pressure Drop ◽  
Newtonian Fluid ◽  
Geometric Mean ◽  
Viscoelastic Fluids ◽  
Momentum Conservation ◽  
Viscoelastic Flows ◽  
Generalized Newtonian Fluid ◽  
Fluid Behavior ◽  
Fluent Software ◽  
Flow Through

In this work, the flow of viscoelastic fluids through axisimmetric converging-diverging channels is analyzed. The solution of mass and momentum conservation equations is obtained numerically via finite volume technique using the Fluent software. The Generalized Newtonian Fluid constitutive equation was used to model the non-Newtonian fluid behavior, using the Shunk-Scriven model for the viscosity, where a weighted geometric mean between shear and extensional viscosities is assumed. The results of pressure drop are compared to the ones predicted by a previously proposed simplified relation (Souza Mendes and Naccache, 2002) between pressure drop and flow rate, for viscoelastic fluids flow through porous media, in order to analyze its performance.

Approximate Calculation of Pressure Drop in Laminar Flow of Generalized Newtonian Fluid Through Channels with Insert

1995 ◽  
Vol 60 (9) ◽  
pp. 1476-1491
Author(s):  
Václav Dolejš ◽  
Petr Doleček ◽  
Ivan Machač ◽  
Bedřich Šiška
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Numerical Solution ◽  
Newtonian Fluid ◽  
Calculation Method ◽  
Approximate Calculation ◽  
Creeping Flow ◽  
Experimental Results ◽  
Generalized Newtonian Fluid

An equation of Rabinowitsch-Mooney type has been suggested for approximate calculation of pressure drop in flow of generalized Newtonian fluid through channels with insert both in the region of creeping flow and at higher values of the Reynolds number, and this calculation method has been verified for four types of insert using own numerical solution and experimental results as well as literature data.

The Effect of Oil and Black on the Injection Molding of EPDM Compounds. I.

1969 ◽  
Vol 42 (5) ◽  
pp. 1321-1335
Author(s):  
William G. DePierri ◽  
J. R. Hopper
Keyword(s):  
Pressure Drop ◽  
Injection Molding ◽  
Flow Behavior ◽  
Injection Pressure ◽  
Flow Properties ◽  
Pressure Drops ◽  
Factors Affecting ◽  
Shear Rates ◽  
Divergent Flow ◽  
High Shear Rates

Abstract Factors affecting the flow properties of EPDM compounds have been studied and the findings of the study applied to the injection molding of these compounds. The level of oil and of black were found to change the flow properties of EPDM compounds. Higher levels of oil decreased the compound viscosity while higher levels of black increased the compound viscosity. The viscosity of the oil influenced compound viscosities. Compounds made with the more viscous (at 210° F) oil had slightly higher viscosities. However, changing from an aromatic to a naphthenic oil of similar viscosity had little effect on the compound viscosity. Compounds made from two different polymers of similar Mooney viscosity were found to have widely divergent flow behavior at high shear rates. Injection molding of EPDM compounds was studied with a molding assembly which had a capillary rheometer as barrel and plunger. Injection pressure data from the molding experiments was found to parallel closely the rheological data. An analysis of the pressure drops in passing through different parts of the mold assembly was made. The total calculated pressure drop agreed closely with the measured pressure drop. The viscous generation of heat was found to be proportional to pressure drop, and an equation is presented which relates the temperature increase to the pressure drop.

Pressure Drops Through Arterial Stenosis Models in Steady Flow Condition

1992 ◽  
Vol 114 (3) ◽  
pp. 416-418 ◽  
Author(s):  
S. Cavalcanti ◽  
P. Bolelli ◽  
E. Belardinelli
Keyword(s):  
Pressure Drop ◽  
Steady Flow ◽  
Flow Condition ◽  
Momentum Equation ◽  
Arterial Stenosis ◽  
Pressure Drops ◽  
Area Reduction ◽  
Steady Flow Condition ◽  
Equidistant Points ◽  
Arterial Stenoses

Measures of pressure drops were made in two different plexiglass models of axial-symmetric arterial stenoses. The stenosis models had the same are reduction (86 percent) but were of different length so as to have a different tapering degree. Pressures were measured in steady flow condition at three equidistant points of the stenosis: upstream, in the middle, and downstream. Results indicate that: the upstream-middle pressure drop is independent of tapering degree but is highly influenced by area reduction; moreover it is much greater than the middle-downstream drop. The upstream-middle pressure drop can be accurately predicted by means of a relationship deduced by the momentum equation.

Flow Measurements in an Aortocoronary Bypass Graft Casting

1996 ◽  
Vol 118 (2) ◽  
pp. 165-171
Author(s):  
E. Y. Kwack ◽  
L. H. Back ◽  
X. M. Ruan ◽  
A. Chaux
Keyword(s):  
Pressure Drop ◽  
Flow Visualization ◽  
Steady Flow ◽  
Flow Rate ◽  
Saphenous Vein ◽  
Poiseuille Flow ◽  
Flow Rates ◽  
Pressure Drops ◽  
Vein Segment ◽  
Flow Pressure

Flow visualization and pressure measurements were carried out in a single valve saphenous vein casting which was made from a saphenous vein segment obtained from a bypass patient at Cedars Sinai Medical Center. Dye was injected to understand the flow around the valve. The dye showed very complex flow patterns around the valve and in the valve sinus, and the cavity formed by a ligated branch. For steady flow, pressure drops across the valve were 0.72, 2.0 and 6.3 mmHg for the physiological flow rates of 45, 84, and 169 ml/min, respectively. Overall pressure drop across the casting (compared to Poiseuille flow for a straight tube) increased with the flow rate, being 130 to 290 percent higher over this flow rate range. In the case of pulsatile flow, pressure drops across the valve were 0.95 and 3.0 mmHg for the flow rates of 47 and 87 ml/min which were 26 and 43 percent higher than those of steady flow. Overall pressure drop was 220 and 360 percent higher for those flow rates compared to Poiseuille flow. The measured spatial pressure distributions along the casting and flow visualization indicated the global nature of the flow field with the accelerated flow through the valve separating and reattaching downstream along the wall in the pressure recovery region. Atherosclerosis may be prone to occur in the lower shear region along the wall beyond the valve tip in the reattachment region, as we have observed in vivo in rabbit experiments.

Experimental and Computational Analyses of Pressure Differentials in Flexible Ducts With Different Bent Angles

2007 ◽  
Author(s):  
Ray R. Taghavi ◽  
Wonjin Jin ◽  
Mario A. Medina
Keyword(s):  
Pressure Drop ◽  
Static Pressure ◽  
Complex Geometry ◽  
Analysis Data ◽  
Secondary Flows ◽  
Low Flow ◽  
Pressure Drops ◽  
Pressure Distributions ◽  
Geometrical Effects ◽  
Cfd Analyses

A set of experimental analyses was conducted to determine static pressure drops inside non-metallic flexible, spiral wire helix core ducts, with different bent angles. In addition, Computational Fluid Dynamics (CFD) solutions were performed and verified by comparing them to the experimental data. The CFD computations were carried out to produce more systematic pressure drop information through these complex-geometry ducts. The experimental setup was constructed according to ASHRAE Standard 120-1999. Five different bent angles (0, 30, 45, 60, and 90 degrees) were tested at relatively low flow rates (11 to 89 CFM). Also, two different bent radii and duct lengths were tested to study flexible duct geometrical effects on static pressure drops. FLUENT 6.2, using RANS based two equations - RNG k-ε model, was used for the CFD analyses. The experimental and CFD results showed that larger bent angles produced larger static pressure drops in the flexible ducts. CFD analysis data were found to be in relatively good agreement with the experimental results for all bent angle cases. However, the deviations became slightly larger at higher velocity regimes and at the longer test sections. Overall, static pressure drop for longer length cases were approximately 0.01in.H2O higher when compared to shorter cases because of the increase in resistance to the flow. Also, the CFD simulations captured more pronounced static pressure drops that were produced along the sharper turns. The stronger secondary flows, which resulted from higher and lower static pressure distributions in the outer and inner surfaces, respectively, contributed to these higher pressure drops.

Peristaltic Motion of a Generalized Newtonian Fluid Through a Porous Medium

2000 ◽  
Vol 69 (2) ◽  
pp. 401-407 ◽  
Author(s):  
Elsayed F. Elshehawey ◽  
Ayman M. F. Sobh ◽  
Elsayed M. E. Elbarbary
Keyword(s):  
Porous Medium ◽  
Newtonian Fluid ◽  
Peristaltic Motion ◽  
Generalized Newtonian Fluid

A model for the stress tensor in dilute suspensions of rigid spheroids in a generalized Newtonian fluid

2019 ◽  
Vol 264 ◽  
pp. 73-84 ◽  
Author(s):  
Jan Domurath ◽  
Gilles Ausias ◽  
Julien Férec ◽  
Gert Heinrich ◽  
Marina Saphiannikova
Keyword(s):  
Stress Tensor ◽  
Newtonian Fluid ◽  
Generalized Newtonian Fluid ◽  
Dilute Suspensions

Experimental Study of Evaporation Heat Transfer Characteristics and Pressure Drops of R410A and R134a in a Multiport Mini-Channel

2009 ◽  
Author(s):  
Jatuporn Kaew-On ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Transfer Coefficients ◽  
Pressure Drops ◽  
Heat Transfer Coefficients ◽  
Evaporation Heat ◽  
Evaporation Heat Transfer ◽  
R 134A

The evaporation heat transfer coefficients and pressure drops of R-410A and R-134a flowing through a horizontal-aluminium rectangular multiport mini-channel having a hydraulic diameter of 3.48 mm are experimentally investigated. The test runs are done at refrigerant mass fluxes ranging between 200 and 400 kg/m2s. The heat fluxes are between 5 and 14.25 kW/m2, and refrigerant saturation temperatures are between 10 and 30 °C. The effects of the refrigerant vapour quality, mass flux, saturation temperature and imposed heat flux on the measured heat transfer coefficient and pressure drop are investigated. The experimental data show that in the same conditions, the heat transfer coefficients of R-410A are about 20–50% higher than those of R-134a, whereas the pressure drops of R-410A are around 50–100% lower than those of R-134a. The new correlations for the evaporation heat transfer coefficient and pressure drop of R-410A and R-134a in a multiport mini-channel are proposed for practical applications.

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