scholarly journals A Force-Balanced Fiber Retardation Model to Predict Fiber-Matrix-Separation during Polymer Processing

2020 ◽  
Vol 4 (4) ◽  
pp. 165
Author(s):  
Christoph Kuhn ◽  
Simon Wehler
Keyword(s):  
Fiber Orientation ◽  
Prediction Models ◽  
Compression Molding ◽  
Polymer Processing ◽  
Force Balance ◽  
Particle Simulation ◽  
Retardation Factor ◽  
Two Phase ◽  
Matrix Separation ◽  
Fiber Matrix

The use of discontinuous fiber reinforced composites in injection and compression molding faces a number of challenges regarding process-induced changes in microstructure, which have a significant influence on the mechanical properties of the final component. The changes in final microstructure are caused by complex fiber movements, such as fiber orientation, attrition and accumulation during flow. While there are existing phenomenological prediction models for both fiber orientation and attrition, the prediction of fiber accumulation due to fiber-matrix separation is currently only possible with a complex mechanistic particle simulation, which is not applicable in industrial simulations. A simplified phenomenological model, the fiber retardation model (FRM), for the prediction of fiber-matrix separation in commercially available software tools is presented in this paper. The model applies a force balance onto an interacting two phase flow of polymer melt and fiber phase and applies a retardation factor Κ to calculate the slowing and accumulation of the fiber phase. The general model is successfully applied to a simple compression molding simulation.

A Parametric Study on Compression Molding of Reference Parts with Integrated Features Using Carbon Composite Production Waste

2015 ◽  
Vol 651-653 ◽  
pp. 458-463
Author(s):  
Mohammed Iqbal Abdul Rasheed ◽  
Bert Rietman ◽  
Hendrikus Antonius Visser ◽  
Remko Akkerman
Keyword(s):  
Compression Molding ◽  
Carbon Composite ◽  
Stiffened Plates ◽  
Consolidation Pressure ◽  
Matrix Separation ◽  
Aspect Ratios ◽  
Composite Production ◽  
Fiber Matrix ◽  
Jamming Effect ◽  
Opening Width

Compression molding of near net-shaped rib-stiffened plates has been performed for a parametric investigation on the filling behavior of chopped woven flake reinforcements. The experimental investigation showed that different aspect ratios of ribs can be filled completely within the tested maximum ratio of flake size to rib opening width of 6.25 and a maximum consolidation pressure of 15 bar. However, defects such as voids, non-impregnated regions and fiber matrix separation may arise depending on the combination of parameters and a mechanical jamming effect caused by the woven architecture of the flakes. A tendency for a limiting consolidation pressure is observed based on the fiber matrix separation. The ability to re-use thermoplastic prepreg cutting waste has been demonstrated.

scholarly journals Prediction Models of Droplet Characteristics Based on the Locally Convergent Configurations in PMMA Microchips

2021 ◽  
Vol 2097 (1) ◽  
pp. 012027
Author(s):  
Zhongxin Liu ◽  
Zhiliang Wang ◽  
Chao Wang ◽  
Jinsong Zhang
Keyword(s):  
Flow Rate ◽  
Relative Position ◽  
Prediction Models ◽  
Continuous Phase ◽  
Lubricating Oil ◽  
Flow Rate Ratio ◽  
Phase Flow ◽  
Exponential Relationship ◽  
Two Phase ◽  
Relationship Of

Abstract This paper novel designed the local convergence configuration in the coaxial channels to study the two-phase flow (lubricating oil (continuous phase, flow rate Q c)/deionized water (dispersed phase, flow rate Q d)). Two geometric control variables, the relative position (x) and tapering characteristics (α), had the different effects on the droplet formation. The increase of relative position x caused the higher frequency and finer droplets, and the increase of convergence angle α, took the opposite effects. The results indicated that the equivalent dimensionless droplet length Ld/Wout and the flow rate ratio Qd/Qc had an exponential relationship of about 1/2. Similarly, it was found that the dispersed droplets generating frequency and the two-phase capillary number, CaTP = uTPμc/σ, had an exponential relationship. The advantage of the convergent configurations in micro-channel was the size and efficiency of droplet generation was very favorable to be controlled by α and x.

Study of the pressure drop in dust scrubber affected by liquid flowability

2019 ◽  
Vol 233 (5) ◽  
pp. 1066-1073 ◽  
Author(s):  
Xiaochuan Li ◽  
Tao Wei ◽  
Xinhao Xu ◽  
Reyna M Knight ◽  
Jiahang Li
Keyword(s):  
Pressure Drop ◽  
Drag Coefficient ◽  
Linear Relationship ◽  
Gas Phase ◽  
Force Balance ◽  
Liquid Level ◽  
Gas Velocity ◽  
Two Phase ◽  
Total Drag ◽  
Quadratic Curve

The complexity of the gas-liquid two-phase flow results in equally complicated pressure drop characteristics for self-excited wet dust scrubbers. In this paper, the pressure drop of the dust scrubber was studied by measuring the total pressure drop R and the differential liquid level Δ H versus the gas velocity v at different initial liquid level b0 values, combined with the liquid flowability. The results showed that the dust scrubber varied its total drag coefficient by changing the differential liquid level Δ H of the liquid-phase and then adjusting the gas-liquid two-phase force balance ahead of and behind the choke. Under the influence of liquid flowability, the throttling strength α exhibited a linear relationship with the gas velocity of the dust scrubber when b0 ≤ 0 mm. The Δ H-v and R- v characteristics of the dust scrubber varied with different values of b0 and v. When b0 > 0, the Δ H-v curve and R- v curve exhibited an explicit quadratic curve relationship. When b0 ≤ 0 mm, the Δ H-v curve and R- v curve exhibited an explicit linear relationship, where the Δ H-v curves can be expressed by a linear equation Δ H = khv+Δ H0, and the gas-phase pressure drop R can be approximately calculated using the differential liquid level Δ H. The liquid flowability can change the choke-sectional to change the total drag coefficient, which reduced in multiple folds with an increase in the gas velocity.

Modeling Two-Phase Flow Inside an Electrical Submersible Pump Stage

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Lissett Barrios ◽  
Mauricio Gargaglione Prado
Keyword(s):  
Drag Coefficient ◽  
Bubble Size ◽  
Flow Behavior ◽  
Mechanistic Model ◽  
Force Balance ◽  
Submersible Pump ◽  
Bubble Behavior ◽  
Two Phase ◽  
Operational Conditions ◽  
Electrical Submersible Pump

Dynamic multiphase flow behavior inside a mixed flow electrical submersible pump (ESP) has been studied experimentally and theoretically for the first time. The overall objectives of this study are to determine the flow patterns and bubble behavior inside the ESP and to predict the operational conditions that cause surging. The theoretical study includes a mechanistic model for the prediction of the flow behavior inside the pump. The model comprises a one-dimensional force balance to predict occurrence of the stagnant bubbles at the channel intake. This model depends on two important variables, namely the stagnant bubble size and the bubble drag coefficient. The bubble size has been measured and a physically based correlation is presented. A new correlation for the drag coefficient is proposed as a function of rotational speed and Reynolds number. The model enables the prediction of the operational envelope of the ESP, namely the transition to surging.

scholarly journals Impact of the Buoyancy–Viscous Force Balance on Two-Phase Flow in Layered Porous Media

2018 ◽  
Vol 124 (1) ◽  
pp. 263-287 ◽  
Author(s):  
Yacine Debbabi ◽  
Matthew D. Jackson ◽  
Gary J. Hampson ◽  
Pablo Salinas
Keyword(s):  
Porous Media ◽  
Two Phase Flow ◽  
Force Balance ◽  
Viscous Force ◽  
Phase Flow ◽  
Two Phase ◽  
Layered Porous Media

Compact Model of Slug Flow in Microchannels

2007 ◽  
Author(s):  
Dong Rip Kim ◽  
Jae-Mo Koo ◽  
Chen Fang ◽  
Julie E. Steinbrenner ◽  
Eon Soo Lee ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Liquid Water ◽  
Slug Flow ◽  
Flow Behavior ◽  
Contact Angles ◽  
Proton Exchange ◽  
Force Balance ◽  
Compact Model ◽  
Two Phase ◽  
Coverage Ratio

This paper presents a theoretical investigation of the movement of liquid droplets and slugs in hydrophobic microchannels and develops a compact model for this type of two-phase flow. This model is used in the prediction of pressure drop and liquid water coverage ratio, key parameters in the operation of Proton Exchange Membrane Fuel Cells (PEMFC), the primary motivation for this work. A semi-empirical, periodic-steady two-phase separated flow compact model is formulated to characterize the slug flow behavior. The momentum equation includes the effects of acceleration, friction and surface tension on the pressure drop. The model considers spatial changes in slug velocity through the use of a force balance formulation. The model uses a departure scheme that computes slug size and shape at entrainment. The steady state slug flow compact model is capable of predicting liquid water coverage ratio and pressure drop using liquid and gas flow rates and advancing/receding triple point contact angles as its only inputs. The results indicate that the pressure drop increases as the droplet formation frequency increases.

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