Prediction of filter expansion during backwashing

2004 ◽  
Vol 4 (5-6) ◽  
pp. 131-138 ◽  
Author(s):  
Ö. Akgiray ◽  
E. Soyer ◽  
E. Yüksel
Keyword(s):  
Particle Shape ◽  
Empirical Equation ◽  
Reynolds Numbers ◽  
Silica Sand ◽  
Shape Effect ◽  
Ergun Equation ◽  
Method Of Calculation ◽  
Glass Spheres ◽  
Filter Backwashing ◽  
Expansion Behaviour

The application of the Ergun equation to predict the expansion of filter media during backwashing is investigated. Fluidization data from the literature have been analyzed and the values k1=3.519 and k2=0.266 have been found to give a very good fit to the data in the range of Reynolds numbers of interest in filter backwashing. An empirical equation that is applicable over a wider range of Reynolds numbers than the Ergun equation is also developed. New experiments have been carried out with glass spheres, plastic spheres, silica sand, and crushed glass. The effect of particle shape on expansion behaviour is investigated. It is found that the influence of particle shape is larger than previously recognized. Furthermore, the shape effect depends on the Reynolds number based on the backwash velocity. The advantages, limitations, and range of applicability of each method of calculation are delineated.

EXTERNAL PARTICLE SHAPE ANALYSIS AND ITS EFFECT ON TRIBOLOGICAL PERFORMANCE OF DISC BRAKE

2016 ◽  
Vol 78 (9) ◽  
Author(s):  
Ahmad Fawwaz Abdul Aziz ◽  
Mohd Kameil Abdul Hamid
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Particle Shape ◽  
Silica Sand ◽  
Variable Load ◽  
Shape Effect ◽  
Disc Brake ◽  
External Particle ◽  
The Road ◽  
Open Design

The open design of disc brake and its location close to the road surface may lead the road particles of various sizes and shapes to enter in between brake pads and disc rotor. This study presents an experimental approach to determine the particle shape effect on friction and wear characteristics of OEM disc brake under different operating condition. Two types of external particles which are road particles and silica sand with two range of size of 200 µm and 400 µm were used. Testing was conducted for variable load and sliding speed. Presence of external particle with various size and shape affect the wear rate, friction coefficient and surface topography of the brake pad. Smaller particle generated more wear. Moreover, the particles which have sharped shape or high angularity resulted in higher weight loss of the pad and contribute to greater formation of compacted wear debris. Wear rate and friction coefficient also increase with contact pressure.   

scholarly journals Particle Shape Effect on Macroscopic Behaviour of Underground Structures: Numerical and Experimental Study

2015 ◽  
Vol 36 (3) ◽  
pp. 67-74 ◽  
Author(s):  
Krzysztof Szarf ◽  
Gael Combe ◽  
Pascal Villard
Keyword(s):  
Particle Shape ◽  
Load Transfer ◽  
Mechanical Performance ◽  
Flexible Structures ◽  
Discrete Element ◽  
Grain Structure ◽  
Experimental Investigations ◽  
Shape Effect ◽  
Underground Structures ◽  
Buried Pipe

Abstract The mechanical performance of underground flexible structures such as buried pipes or culverts made of plastics depend not only on the properties of the structure, but also on the material surrounding it. Flexible drains can deflect by 30% with the joints staying tight, or even invert. Large deformations of the structure are difficult to model in the framework of Finite Element Method, but straightforward in Discrete Element Methods. Moreover, Discrete Element approach is able to provide information about the grain-grain and grain-structure interactions at the microscale. This paper presents numerical and experimental investigations of flexible buried pipe behaviour with focus placed on load transfer above the buried structure. Numerical modeling was able to reproduce the experimental results. Load repartition was observed, being affected by a number of factors such as particle shape, pipe friction and pipe stiffness.

scholarly journals Particle-Based Numerical Simulation Study of Solid Particle Erosion of Ductile Materials Leading to an Erosion Model, Including the Particle Shape Effect

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 286
Author(s):  
Shoya Mohseni-Mofidi ◽  
Eric Drescher ◽  
Harald Kruggel-Emden ◽  
Matthias Teschner ◽  
Claas Bierwisch
Keyword(s):  
Solid Particle ◽  
Particle Shape ◽  
Solid Particles ◽  
Solid Particle Erosion ◽  
Shape Effect ◽  
Particle Erosion ◽  
Erosion Model ◽  
Ductile Materials ◽  
Erosion Behavior ◽  
Numerical Predictions

Solid particle erosion inevitably occurs if a gas–solid or liquid–solid mixture is in contact with a surface, e.g., in pneumatic conveyors. Having a good understanding of this complex phenomenon enables one to reduce the maintenance costs in several industrial applications by designing components that have longer lifetimes. In this paper, we propose a methodology to numerically investigate erosion behavior of ductile materials. We employ smoothed particle hydrodynamics that can easily deal with large deformations and fractures as a truly meshless method. In addition, a new contact model was developed in order to robustly handle contacts around sharp corners of the solid particles. The numerical predictions of erosion are compared with experiments for stainless steel AISI 304, showing that we are able to properly predict the erosion behavior as a function of impact angle. We present a powerful tool to conveniently study the effect of important parameters, such as solid particle shapes, which are not simple to study in experiments. Using the methodology, we study the effect of a solid particle shape and conclude that, in addition to angularity, aspect ratio also plays an important role by increasing the probability of the solid particles to rotate after impact. Finally, we are able to extend a widely used erosion model by a term that considers a solid particle shape.

Exploration of particle shape effect on Cu-H2O nanoparticles over a moving plate

2019 ◽  
Vol 30 (4) ◽  
pp. 1867-1879 ◽  
Author(s):  
Ganesh Kumar K. ◽  
Chamkha Ali J. ◽  
Prasannakumara B.C. ◽  
Jyothi A.M.
Keyword(s):  
Heat Transfer ◽  
Particle Shape ◽  
Nonlinear Thermal Radiation ◽  
Shape Effect ◽  
Moving Plate ◽  
Content Type ◽  
Opposite Trend ◽  
Thermodynamic Performance ◽  
Particle Shape Effect ◽  
Nanoparticle Shapes

Purpose This paper aims to explore particle shape effect on Cu-H2O nanoparticles over a moving plate in the presence of nonlinear thermal radiation. To characterize the effect, particle shape and viscous dissipation are considered. Convergent solutions for the resulting nonlinear systems are derived and the effects of embedded parameters of interest on velocity and temperature field are examined. Design/methodology/approach The Runge–Kutta–Fehlberg fourth-fifth order method along with shooting technique is used to solve the governing equations (6) and (7) with boundary conditions (8). A suitable finite value of η∞ is considered in such a way that the boundary conditions are satisfied asymptotically. Findings The results show an increase in both the heat transfer and thermodynamic performance of the system. However, among the three nanoparticle shapes, disk shape exhibited better heat transfer characteristics and heat transfer rate. On the other hand, the velocity profile enhances with increasing values of ϕ in the first solution, but the opposite trend was found in the second solution. Originality/value The present paper deals with an exploration of particle shape effect on Cu-H2O nanoparticles over a moving plate in the presence of nonlinear thermal radiation. To characterize the effect, particle shape and viscous dissipation are considered. Convergent solutions for the resulting nonlinear systems are derived and the effects of embedded parameters of interest on velocity and temperature field are examined. The skin friction coefficient and Nusselt number are numerically tabulated and discussed. The results show an increase in both heat transfer and thermodynamic performance of the system. However, among the three nanoparticle shapes, disk shape exhibited better heat-transfer characteristics and heat-transfer rate. On the other hand, the velocity profile enhances with increasing values of ϕ in the first solution, but the opposite trend was found in the second solution.

scholarly journals Numerical Study of Particle Morphology Effect on the Angle of Repose for Coarse Assemblies Using DEM

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Jing Chen ◽  
Rui Gao ◽  
Yangzepeng Liu
Keyword(s):  
Particle Shape ◽  
Laboratory Tests ◽  
Sliding Friction ◽  
Numerical Study ◽  
Dominant Role ◽  
Particle Morphology ◽  
Angle Of Repose ◽  
Shape Effect ◽  
Shape Factors ◽  
Coefficient Of Sliding Friction

The morphologies of coarse particles are usually irregular and play a dominant role in the mechanical behaviors of the particle assemblies. This paper quantitatively studies the effect of particle shape on the angle of repose, which is an important macroscopic parameter for ballast materials, via laboratory tests and numerical simulations by means of the discrete element method (DEM). Forty ballast particle templates and four simply created clump templates are reconstructed using an image-based method and quantified with two shape factors, sphericity and convexity. A series of simulations are conducted with the coefficient of sliding friction between particles changing from 0.2 to 0.6 at an interval of 0.1 to study its influence on various shapes of particles, and an appropriate value of sliding friction coefficient is chosen for the comparison of particle shape effect. The results show that increasing sphericity and convexity can significantly decrease the angle of repose, and the real ballast model gives a more realistic angle of repose behaviors as that of laboratory tests compared to simply created models. By analyzing the characteristics of particle motions and contacts from a microscopic perspective, the mechanism of particle shape attributed to the formation of granular aggregation is also discussed and revealed in this research.

Effects of Fluid Viscosity and Impingement Angle on Submerged Jet Flowfields

2018 ◽  
Author(s):  
Soroor Karimi ◽  
Matthew Fulton ◽  
Siamack A. Shirazi ◽  
Brenton McLaury
Keyword(s):  
Maximum Velocity ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
Fluid Viscosity ◽  
Impingement Angle ◽  
Submerged Jet ◽  
Glass Spheres ◽  
Image Velocimetry ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Experiments

Many researchers have utilized submerged jet impingement geometry to study solid particle erosion/corrosion. However, only a few studies have investigated changing impingement angle and fluid viscosity. In this study, Particle Image Velocimetry (PIV) experiments were conducted using 14 micron glass spheres for direct impingement geometry at viscosities of 1, 14, and 55 cP. These viscosities correspond to Reynolds numbers of approximately 57000, 4000, and 1000, respectively. It was observed that by increasing the viscosity the flow exiting the nozzle transitioned from extremely turbulent to laminar flow. The data indicated fully turbulent flow at the outlet for viscosities of 1 and 14 cP. In the case of 55 cP flow, the flow exiting the nozzle became laminar contributing to a higher maximum velocity in 55 cP flow. Experiments at these viscosities were also conducted at impingement angles of 90, 75, and 45 degrees to investigate the effects of the impinging jet angle on a flat plate. Additionally, a series of Computational Fluid Dynamics (CFD) simulations of the flowfield were performed to compare with the experimental data collected in this paper.

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