Effect of the entry cone angle of the spinneret hole on the flow characteristics of the polymer melt

1987 ◽  
Vol 18 (3) ◽  
pp. 213-216 ◽  
Author(s):  
V. P. Pervadchuk ◽  
I. O. Glot ◽  
V. I. Yankov ◽  
A. S. Borisov ◽  
Yu. A. Vinogradov
Keyword(s):  
Cone Angle ◽  
Flow Characteristics ◽  
Polymer Melt ◽  
Spinneret Hole

scholarly journals Calculation of flow characteristics of liquid fuel supplied through pressure jet atomizers of small-sized gas turbine engines

2021 ◽  
Vol 20 (2) ◽  
pp. 19-35
Author(s):  
N. I. Gurakov ◽  
I. A. Zubrilin ◽  
M. Hernandez Morales ◽  
D. V. Yakushkin ◽  
A. A. Didenko ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Liquid Fuel ◽  
Cone Angle ◽  
Flow Characteristics ◽  
Design Parameters ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Semi Empirical

The paper presents the results of studying the flow characteristics of liquid fuel in pressure jet atomizers of small-sized gas turbine engines with nozzle diameters of 0.4-0.6 mm for various operating and design parameters. The study was carried out using experimental measurements, semi-empirical correlations and CFD (computational fluid dynamics) methods. The Euler approach, the volume- of- fluid (VOF) method, was used to model multiphase flows in CFD simulations. Good agreement was obtained between experimental and predicted data on the fuel coefficient and the primary spray cone angle at the nozzle outlet. Besides, the assessment of the applicability of semi-empirical techniques for the nozzle configurations under consideration is given. In the future, the flow characteristics in question (the nozzle flow rate, the fuel film thickness, and the primary spray cone angle) can be used to determine the mean diameter of the droplets (SMD) required to fully determine the boundary conditions of fuel injection when modeling combustion processes in combustion chambers of small-sized gas turbine engines.

Analysis of Central Bursting Defects in Extrusion and Wire Drawing

1968 ◽  
Vol 90 (1) ◽  
pp. 79-90 ◽  
Author(s):  
B. Avitzur
Keyword(s):  
Strain Rate ◽  
Fracture Criterion ◽  
Yield Criterion ◽  
Cone Angle ◽  
Flow Characteristics ◽  
Wire Drawing ◽  
Ductile Material ◽  
Stress Deviator ◽  
Major Conclusion ◽  
Metal Properties

The central burst defect, also called chevroning, in the extruded or drawn product is analyzed. A criterion for the unique conditions that promote this defect has been derived. Measures to prevent the occurrence of central burst are indicated. A major conclusion of the study is that, for a range of combinations of cone angle, reduction, and friction, central bursting is expected in any metal that can be called “Mises’ material.”1 Under such a combination (reduction, cone angle, and friction), even the most ductile material can burst centrally. The flow characteristics, described by Mises’ stress deviator-strain rate relations associated with Mises’ yield criterion, are the only metal properties needed to predict central bursting. No additional fracture criterion is associated with this failure.

scholarly journals Coupled thermal-structural modelling and experimental validation of spiral mandrel die

2020 ◽  
Vol 111 (11-12) ◽  
pp. 3047-3061
Author(s):  
Yi Nie ◽  
Ian Michael Cameron ◽  
Johann Sienz ◽  
Yueh-Jaw Lin ◽  
Wei Sun
Keyword(s):  
Thermal Analysis ◽  
Experimental Validation ◽  
Flow Characteristics ◽  
Polymer Melt ◽  
Theoretical Method ◽  
Processing Parameters ◽  
Flow Channel ◽  
Maximum Pressure ◽  
Structural Modelling ◽  
Mapping Algorithm

AbstractThe conventional theoretical method to calculate deformations and stress states is only limited to a few cases of simple extrusion dies due to a number of assumptions and simplifications. A coupled thermal-structural modelling framework incorporating finite element method is thus developed and implemented to determine the mechanical performances of the complicated spiral mandrel die, which has a complex geometrical feature of spiral grooves and is exposed to severe conditions of thermal load and high pressure. The steady-state thermal analysis is carried out by mapping the temperature load on the flow channel from previously simulated flow characteristics of polymer melt. The structural analysis takes inputs from both thermal analysis and previously simulated pressure on polymer melt. Both the temperature and pressure loads on flow channel are transferred via the Smart Bucket Surface mapping algorithm. The mechanical properties of the spiral mandrel die are evaluated by analysing the deformation and stress distribution. The experimental validation is conducted to demonstrate the effectiveness of the numerical model. The effects of both structure parameters of the spiral mandrel and processing parameters upon the maximum stress in the die body and the maximum pressure induced deformation at the die orifice are investigated.

A study of novel viscous dissipation measurement for polymer melts in microchannels

2010 ◽  
Vol 224 (9) ◽  
pp. 2027-2035 ◽  
Author(s):  
B Xu ◽  
M Wang ◽  
T Yu ◽  
D Zhao
Keyword(s):  
Viscous Dissipation ◽  
High Density Polyethylene ◽  
Polymer Melts ◽  
Flow Characteristics ◽  
Rheological Behaviour ◽  
Polymer Melt ◽  
Experimental Results ◽  
Maximum Temperature ◽  
Number Of Factors ◽  
Different Temperatures

Studies on the rheological behaviour of polymer melts, flowing through microchannels, are complicated because a large number of factors affect the melt viscosity. One such factor, viscous dissipation, is investigated in the current work through a novel experimental technique that is used in determining the viscous dissipation of a polymer melt flowing through microchannels. Relative tests are conducted using melts of high-density polyethylene (HDPE) extruded through several capillary dies at different temperatures. Experimental results indicate that the temperature rises due to viscous dissipation increase with increasing shear rate. In addition, simulations considering viscous dissipation are carried out. The comparison of the experimental results with those predicted from the simulations at different melt temperatures indicates that the maximum temperature rise deviation is about 15 per cent. Therefore, the measurement method of viscous dissipation is available, which is helpful to better understand the flow characteristics of microchannels.

Flow in Atomizers: Influence of Different Parameters on the Performance Characteristics of Plain Orifice Atomizer and Pressure Swirl Atomizer of a Fuel Injection System of Gas Turbine Combustor

2005 ◽  
Author(s):  
Digvijay B. Kulshreshtha ◽  
S. A. Channiwala
Keyword(s):  
Surface Tension ◽  
Drop Size ◽  
Cone Angle ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Performance Characteristics ◽  
Bulk Liquid ◽  
Atomization Process ◽  
Spray Cone ◽  
Pressure Swirl

The atomization process is essentially one in which bulk liquid is converted into small drops. Basically, it can be considered as a disruption of the consolidating influence of surface tension by the action of internal and external forces. In the absence of such disruptive forces, surface tension tends to pull the liquid into the form of a sphere, since this has the minimum surface energy. Liquid viscosity exerts a stabilizing influence by opposing any change in system geometry. On the other end, aerodynamic forces acting on the liquid surface may promote the disruption process by applying an external distortion force to the bulk liquid. Breakup occurs when the magnitude of the disruptive force just exceeds the consolidating surface tension force. In twin fluid atomizers of the air-blast type and air assist type, atomization and spray dispersion tend to be dominated by air momentum forces, with hydrodynamic processes playing only a secondary role. With pressure swirl nozzles, the internal flow characteristics are of primary importance, because they govern the thickness and uniformity of the annular liquid film formed in the final discharge orifice as well as the relative magnitude of the axial and tangential components of velocity of this film. It is therefore of great practical interest to examine the interrelationships that exist between internal flow characteristics, nozzle design variables, and important spray features such as cone angle and mean drop size. The various equations that have been derived for nozzle discharge coefficient are discussed because this coefficient not only affects the flow rate of any given nozzle but also can be used to calculate its velocity coefficients and spray cone angle. Consideration is also given to the complex flow situations that arise on the surface of a rotating cup or disk. These flow characteristics are of basic importance to the successful operation of atomizers, because they exercise a controlling influence on the nature of the atomization process, the quality of atomization, and distribution of drop sizes in the spray. For plain orifice atomizers, the key geometrical variables are the orifice length and diameter. Final orifice diameter is of prime importance for pressure swirl atomizers. The absence of any theoretical treatment of the atomization process has led to the evolution of empirical equations to express the relationship between the mean drop size in a spray and the variable liquid properties. This paper includes the study of different parameters that affect the flow in plain orifice and pressure swirl atomizers. The paper also includes the performance characteristics of plain orifice and pressure swirl atomizers.

Experimental Study of Hydraulic Flip Phenomenon inside Diesel Nozzles Using Diesel and Biodiesel

2014 ◽  
Vol 945-949 ◽  
pp. 940-943 ◽  
Author(s):  
Zhuang Shao ◽  
Zhi Xia He ◽  
Zhi Wei Zhou ◽  
Xi Cheng Tao
Keyword(s):  
Discharge Coefficient ◽  
Cone Angle ◽  
Great Influence ◽  
Flow Characteristics ◽  
Injection Pressure ◽  
Cavitating Flow ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
The Difference ◽  
Biodiesel Fuels

As cavitation inside diesel nozzles can improve the spray characteristics, it has long been a hot issue. And together with the increasing attention of biodiesel, it is essential to identify the difference of cavitating flow characteristics between diesel and biodiesel. What’s more, the hydraulic flip phenomenon and cavitating flow with decreasing injection pressure hasn’t been studied. Based on this, cavitating flow inside transparent nozzles of diesel and biodiesel fuels with increasing and decreasing injection pressure was investigated in this paper. Experimental results showed that are quite different from the disappearance of it and it is harder to disappear. Biodiesel and longer nozzle orifices were hard for the hydraulic flip phenomenon to occur, and the disappearance of hydraulic flip phenomenon has great influence on the spray cone angle and the discharge coefficient.

Control-Oriented Modeling of an Injection Molding Machine Including the Fill-to-Pack Transition

2000 ◽  
Author(s):  
Danian Zheng ◽  
Andrew Alleyne ◽  
Heather Havlicsek
Keyword(s):  
Injection Molding ◽  
Controller Design ◽  
Flow Characteristics ◽  
Polymer Melt ◽  
Hydraulic Actuator ◽  
Molding Machine ◽  
Injection Molding Machine ◽  
Digitally Controlled ◽  
Engineering Models ◽  
Injection Cycle

Abstract In this paper the modeling of a typical injection cycle for an injection molding machine (IMM) is examined. Both the mold filling and mold packing phases of the cycle are examined along with a critical fill-to-pack transition. The novelty in this modeling work is that the non-linear model considers both the machine hydraulic actuator and polymer flow characteristics in extensive detail. The resulting model will provide simulation capabilities to facilitate machine controller design; however the actual controller is not the focus of the current work. The modeling is based on (a) the characteristics of digitally controlled electrohydraulic valves, (b) the dynamics of the hydraulic actuator ram system, and (c) the gross polymer melt behavior determined from simple polymer engineering models. The simulation model is validated against experimental data and demonstrates the availability of a relatively accurate system model for full cycle control of this electrohydraulic system.

Numerical study of polymer melt flow in a three-dimensional sudden expansion: viscous dissipation effects

2014 ◽  
Vol 34 (8) ◽  
pp. 755-764
Author(s):  
Mustafa Tutar ◽  
Ali Karakus
Keyword(s):  
Viscous Dissipation ◽  
Stokes Equations ◽  
Numerical Study ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Polymer Melt ◽  
Sudden Expansion ◽  
Melt Flow

Abstract This numerical paper presents the effects of viscous dissipation on both hydrodynamic flow behavior and thermal flow characteristics of fluid included in rheological polymer flow analysis. The shear rate dependence of the viscosity is modeled using a modified form of the Cross constitutive equation, while the density changes are modeled using the modified Tait state of equation. The Navier-Stokes equations are solved in a sequential, decoupled manner with energy conservation equations using a finite volume method based fluid flow solver. Hydrodynamic and thermal boundary layer developments in an asymmetric sudden expansion for different velocity and melt flow injection temperature boundary and geometry conditions are determined under the influence of viscous dissipation effects and the results are compared with each other to measure the relative effects of viscous dissipation on the interactions of these layers for a commercial polymer melt flow, namely polypropylene (PP). The numerical results demonstrate that proposed mathematical and numerical formulations for viscosity and density variations including viscous heating terms lead to more accurate representation of the polymer melt flow and heat transfer phenomena in plane channels or mold cavity associated with a sudden expansion.

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