Influence of Morphology on Flow Law Characteristics in Open-Cell Foams: An Overview of Usual Approaches and Correlations

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Prashant Kumar ◽  
Frédéric Topin
Keyword(s):  
High Performance ◽  
Pore Space ◽  
Cross Sectional ◽  
Open Cell ◽  
Industrial Systems ◽  
Wide Range ◽  
Open Cell Foam ◽  
Successful Design ◽  
Open Cell Foams ◽  
Flow Law

Foam structures have been a subject of intensive research since the last decade. The pore space in open-cell foam is interconnected, forming perforated channels of varying cross-sectional areas where fluid can flow. Knowledge of pressure drop induced by these foam matrices is essential for successful design and operation of high-performance industrial systems. In this context, analytical correlations were derived for the determination of Darcian permeability (KD) and Forchheimer inertia coefficient (CFor) in open-cell foams of different strut shapes. It has been shown that the flow law characteristics are strongly dependent on strut shape, strut characteristic dimension, and length. The applicability of new correlations was examined by comparing and validating the numerical and experimental flow law characteristics data against the predicted ones. An excellent agreement has been observed for the foam structures of different materials and variable texture in a wide range of porosity and Reynolds number.

State-of-the-Art of Pressure Drop in Open-Cell Porous Foams: Review of Experiments and Correlations

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Prashant Kumar ◽  
Frédéric Topin
Keyword(s):  
Pressure Drop ◽  
High Performance ◽  
Industrial Applications ◽  
Morphological Parameters ◽  
Empirical Correlations ◽  
Open Cell ◽  
Substantial Progress ◽  
Successful Design ◽  
Open Cell Foams ◽  
Microporous Media

Foam structures are a class of modern microporous media that possesses high thermal conductivity, large accessible specific surface area, and high porosities. Nowadays, industrial applications, such as filtration, heat exchange and chemical reaction, etc., utilize porous media such as open-cell foams. Knowledge of pressure drop induced by these foam matrices is essential for successful design and operation of high-performance industrial systems. The homogenized pressure drop data in the literature are widely dispersed (up two orders of magnitude) despite numerous researches has been conducted since two decades. Most of the empirical pressure drop correlations were derived using Ergun-like approach. In this view, a careful evaluation of empirical correlations as well as the relationship of intrinsic flow law characteristics (permeability and inertia coefficient) with morphological parameters is imperative. This paper presents the start-of-the-art of various pressure drop correlations as well as highlights the ambiguities and inconsistencies in various definitions of several key parameters. The applicability of the empirical correlations presented in the literature was examined by comparing them against numerically calculated pressure drop data of open-cell foams (metal and ceramic) for the porosities ranging from 0.60 up to 0.95. A comprehensive study has been conducted to identify the reasons of dispersed pressure drop data in the literature. Although substantial progress has been made in the field of fluid flow in open-cell foams, it is yet difficult to predict pressure drop data from a given set of morphological parameters.

FEM Modeling of Failure of a Foam Single Cell

2010 ◽  
Vol 165 ◽  
pp. 400-403 ◽  
Author(s):  
Wiesław Szymczyk ◽  
Danuta Miedzińska
Keyword(s):  
Effective Properties ◽  
Failure Process ◽  
Polyurethane Foams ◽  
Fem Modeling ◽  
Open Cell ◽  
Rail Vehicles ◽  
Open Cell Foam ◽  
Different Types ◽  
Open Cell Foams ◽  
Energy Absorbing

. The paper deals with the numerical analysis of foam materials. Open cell foam is investigated. Numerical simulations enable prediction of failure process and assessment of effective properties of the modeled foam structures [1]. Metal as well as polyurethane foams exhibit interesting properties. They are light, possess good acoustic and/or magnetic isolation, have ability to absorb energy of vibration and impacts [2]. They are used for sandwich panels, hit absorbers (i.e. as elements of buffer constructions in rail vehicles), fillers of construction parts, bodies of vehicles (i.e. floating combat vehicles), dividing walls on vessels and others. Specially prepared open cell foams demonstrate auxetic properties [3] and shape memory effect [4]. Such materials are very good for seats in aircrafts, which may protect pilots and passengers during crashes and restrict heavy backbone injuries. Foams are also applied for filtering purposes. Foams themselves or in combination with different types of fillers (i.e. elastomers) or ceramic reinforcement may be used for impact energy absorbing panels for military purposes (protection against explosion shock wave and splinters).

Theory and Simulation of Fiber Texture Formation and Rheology of Carbonaceous Mesophase Fibers

2001 ◽  
Vol 709 ◽  
Author(s):  
A. D. Rey
Keyword(s):  
Liquid Crystals ◽  
High Performance ◽  
Melt Spinning ◽  
Elongational Flow ◽  
Fiber Texture ◽  
Texture Formation ◽  
Cross Sectional ◽  
Wide Range ◽  
Spinning Process ◽  
Sectional Shape

ABSTRACTCarbonaceous mesophases are discotic nematic liquid crystals that are spun into high performance carbon fibers using the melt spinning process. The spinning process produces a wide range of different fiber textures and cross-sectional shapes. Circular planar polar (PP), circular planar radial (PR) textures, ribbon planar radial (RPR), and ribbon planar line (RPL) textures are ubiquitous ones. This paper presents, solves, and validates a model of mesophase fiber texture formation based on the classical Landau-de Gennes theory of liquid crystals, adapted here to carbonaceous mesophases. The effects of fiber cross-sectional shape and elongational flow on texture formation are characterized. Emphasis is on qualitative model validation using existing experimental data [1, 2]. The results provide additional knowledge on how to optimize and control mesophase fiber textures.

Sound Attenuation and Prediction of Porous Media Properties in Hybrid Ducts Utilizing Spatially Periodic Area Changes

2008 ◽  
Author(s):  
Lisa J. Burton ◽  
Donald B. Bliss ◽  
Linda P. Franzoni
Keyword(s):  
Porous Material ◽  
Cross Section ◽  
Pass Band ◽  
Cross Sectional ◽  
Open Cell ◽  
One Dimensional ◽  
Open Cell Foam ◽  
Spatially Periodic ◽  
The Cross ◽  
Cell Foam

A theory based on cross-sectional averaging is developed to analyze quasi-one-dimensional acoustic propagation in hybrid ducts with two propagation media in the cross-section. Specifically, ducts lined with a thick layer of porous material are considered. The porous material makes the duct wavenumber complex, changing the phase speed and introducing attenuation. To lowest order, the wavenumber depends only on the ratio of cross-sectional areas and the properties of the constituent media, and surprisingly not on the material configuration in the cross-section. High frequency accuracy can be improved by using a small correction that includes shape coefficients that depend on the cross-sectional configurations. If the propagation wavenumber is measured experimentally in a hybrid duct, the complex effective sound speed and density, fundamental porous material properties, can be extracted relatively easily. Experimentally, open cell foam samples line the sides of a tube closed at one end, and the complex wavenumber is determined from standing wave measurements. The cross-sectional averaging theory is then used to determine the acoustic properties of the open-cell foam. Results are compared for various lining configurations to assess the accuracy of the method. Another application of this work is the theoretical and experimental study of the propagation of quasi one-dimensional acoustic waves through a duct with spatially periodic area changes. This configuration exhibits stop-band and pass-band behavior, with substantially reduced sound transmission in stop bands, but little effect in pass bands. The regions of the duct with larger cross-sectional area are partially filled with an annular region of porous material to provide pass-band attenuation, leaving a constant area passage for airflow. Predictions and measurements for hybrid ducts with periodic area changes are presented. A muffler designed to place engine harmonics in targeted stop-bands is described.

scholarly journals An appraisal of the application of open-cell foams in automotive SCR systems

2020 ◽  
Vol 197 ◽  
pp. 06007
Author(s):  
Andrea Vespertini ◽  
Augusto Della Torre ◽  
Gianluca Montenegro ◽  
Angelo Onorati ◽  
Enrico Tronconi ◽  
...  
Keyword(s):  
Preliminary Analysis ◽  
Operating Conditions ◽  
Cfd Model ◽  
Open Cell ◽  
Geometrical Properties ◽  
Pressure Injection ◽  
Open Cell Foam ◽  
Transfer Behavior ◽  
Open Cell Foams ◽  
Cell Foam

This work aims to investigate the possibility to apply open-cell foams as catalytic substrates in SCR systems for Diesel engines, as a replacement of traditional honeycombs. In the literature, many studies compare the performance of foams and honeycombs as catalytic substrates, showing, in general, a better mass transfer behavior in foams, compensated on the other hand by a higher pressure drop. In this work, we consider the low-pressure injection of Ad-Blue and we evaluate the performance of the open-cell foam in enhancing the mixing and the evaporation of the spray. A Eulerian-Lagrangian CFD model has been adopted to simulate the spray evolution and its interaction with the microstructure of the open-cell foam. The model has been applied to evaluate the spray evaporation and the uniformity of the ammonia distribution in different sections of the substrate. Different operating conditions were tested comparing substrates with different geometrical properties. The results of this preliminary analysis can be regarded as promising, showing the capability of the foam to enhance the mixing of the spray and to achieve a uniform distribution of the ammonia over all the catalyst substrate.

Nonlinear Modeling of 3D Open-Cell Foams

1999 ◽  
Author(s):  
Yu Wang ◽  
Alberto M. Cuitiño
Keyword(s):  
Strain Energy ◽  
Nonlinear Modeling ◽  
Three Dimensional ◽  
Strain Energy Function ◽  
Nonlinear Material ◽  
Open Cell ◽  
Wide Range ◽  
Open Cell Foams ◽  
Explicit Correlation ◽  
Strain Energy Functions

Abstract In this article, we present a hyperelastic model for light and compliant open cell foams with an explicit correlation between microstructure and macroscopic behavior. The model describes a large number of three dimensional structures with regular and irregular cells. The theory is based on the formulation of strain-energy function accounting for stretching which is the main deformation mechanism in this type of materials. Within the same framework, however, bending, shear and twisting energies can also be incorporated. The formulation incorporates nonlinear kinematics which traces the evolution of the structure during loading process and its effects on the constitutive behavior, including the cases where configurational transformations are present leading to non-convex strain-energy functions. Also nonlinear material effects at local or beam level are introduced to accommodate a wide range of different material behaviors. Since the micromechanical formulation presented here has explicit correlation with the foam structure, it preserves in the constitutive relation the symmetries or directional properties of the corresponding structures, including the cases of re-entrant foams which exhibit negative Poisson’s ratio effects. The model captures the central features exhibit by these materials. Predictions of the model for macroscopic uniaxial strain are presented in this article.

An Elastic Micropolar Mixture Theory Approach for Predicting Elastic Properties of Open Cell Foams

2007 ◽  
Author(s):  
Shreehari Elangovan ◽  
Burhanettin S. Altan ◽  
Gregory M. Odegard
Keyword(s):  
Cellular Structure ◽  
Mixture Theory ◽  
Constitutive Relationship ◽  
Elastic Response ◽  
Theory Approach ◽  
Wood Material ◽  
Open Cell ◽  
Balsa Wood ◽  
Open Cell Foam ◽  
Open Cell Foams

A constitutive model has been developed to predict the elastic response of two dimensional balsa wood material with a distribution of cell geometries. Two planar triangular grids, each assumed to represent the structural network of an open cell foam material, are superimposed to model an overall cellular structure with a distribution of cell geometries. The elastic mixture theory is applied in conjunction with the micropolar elasticity theory to homogenize the cellular structure and to establish the overall constitutive relationship.

scholarly journals STATISTICAL ANALYSIS OF THE LOCAL STRUT THICKNESS OF OPEN CELL FOAMS

2013 ◽  
Vol 32 (1) ◽  
pp. 1 ◽  
Author(s):  
André Liebscher ◽  
Claudia Redenbach
Keyword(s):  
Euclidean Distance ◽  
Interconnected Network ◽  
Micro Computed Tomography ◽  
Cross Sectional ◽  
Open Cell ◽  
Strut Thickness ◽  
Thickness Profile ◽  
Open Cell Foams ◽  
Polynomial Models ◽  
Sectional Shape

Open cell foams are formed by an interconnected network of struts whose thickness varies locally. These variations were shown to have an impact on the elastic and thermal properties of the foam. In this paper we quantify the local strut thickness by means of micro computed tomography (µCT) imaging. We introduce a skeletonization based topological decomposition of the foam structure into its vertices and struts. This allows to estimate the thickness of individual strut segments by the Euclidean distance transform, where an appropriate correction for struts with nonspherical cross-sectional shape is applied. Conflating these estimates based on the strut lengths results in a strut thickness profile for the entire foam. Polynomial models for the strut thickness profile are investigated by means of a regression analysis.

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