Numerical calculation of pneumatic conveying in horizontal channels and pipes: Detailed analysis of conveying behaviour

Laı́n, Santiago; Sommerfeld, Martin

doi:10.1016/j.ijmultiphaseflow.2011.09.006

Cited by 80 publications

(41 citation statements)

References 28 publications

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“…For the present calculations typically about 25 to 55 coupling iterations with an under-relaxation factor between 0.1 and 0.5 were necessary in order to yield convergence of the Euler-Lagrange coupling. This convergence behaviour was clearly demonstrated by Lain and Sommerfeld (2012).…”

Section: Euler/lagrange Approachmentioning

confidence: 54%

Numerical analysis of sprays with an advanced collision model

Sommerfeld

Laı́n

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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Modelling of collisions between liquid droplets in the frame of a Lagrangian spray simulation has still many open issues, especially when considering higher viscous droplets and if colliding droplets have a large size difference. A generalisation of the collision maps is attempted based on the behaviour of characteristic points, namely the triple point where bouncing, coalescence and stretching separation coincide and the critical Weber-number where reflexive separation first occurs in head-on collisions. This is done by correlating experimental data with respect to the Capillary number with the Ohnesorge-number for the triple point and the critical Weber-number is also well described by a correlation the Ohnesorge-number. Based on these results the boundary line between stretching separation and coalescence is found by adapting the Jiang et al. (1992) correlation. For the upper boundary of reflexive separation the shifted Ashgriz and Poo (1990) correlation is used. It was however so far not possible to predict the lower bouncing boundary through the Estrade et al. (1999) boundary line correctly. The proposed boundary-line models were validated for various liquid, however still considering only a size ratio of one. With the developed three-line boundary model Euler/Lagrange numerical calculations for a simple spray system were conducted and the droplet collisions were analysed with respect to their occurrence. Droplet collision modelling is performed on the basis of the stochastic droplet collision model, also considering the influence of impact efficiency, which so far was neglected for most spray simulations. The comparison with measurements showed reasonable good agreement for all properties. KeywordsDroplet collisions, stochastic collision model, impact efficiency, collision outcomes, Euler/Lagrange calculations, spray simulations. IntroductionIn numerous technical and industrial spraying systems higher viscous liquids, suspensions or solutions are being atomised. Examples are liquid fuels (including bio-fluids) in combustion systems, liquid melts or other mineral melts in the field of materiel science and spray drying of foodstuff or pharmaceutical materials. Therefore, in a numerical calculation of such spraying systems, mostly done with an Euler/Lagrange approach, the resulting different liquid properties have to be accounted for. Here the focus is related to droplet collision modelling. Hence, established droplet collision models have to be generalized regarding liquid properties, mainly viscosity and surface tension. Since colliding droplets may have considerable different size also the droplet size ratio is an important parameter to be considered in droplet collision modelling. In order to model droplet collisions in the frame of the Lagrangian droplet parcel concept, where only pointmasses are tracked, applied to spraying systems several elementary processes have to be considered (Sommerfeld and Kuschel 2016). The first step is the detection of possible collisions between two droplets. In orde...

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Section: Euler/lagrange Approachmentioning

confidence: 54%

Numerical analysis of sprays with an advanced collision model

Sommerfeld

Laı́n

2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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“…This figure shows that the mass flux of particles near the inner wall is greater for the case of high wall roughness compared to the low wall roughness case and the mass flux also increases with increasing values of radius ratio. The effect of wall roughness on particle distribution in a horizontal pipe was also investigated by Lain and Sommerfeld [30]. They concluded that conveying of particles in a horizontal pipe with higher wall roughness results in the so-called "focusing effect," whereby the particles colliding with the curved walls are bounced back towards the core of the pipe cross-section.…”

Section: Resultsmentioning

confidence: 97%

The effects of wall roughness on erosion rate in gas–solid turbulent annular pipe flow

et al. 2015

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“…Types of flows Re p Kim and Balachandar (2012) An isolated finite-sized particle subjected to isotropic turbulent cross-flow 100, 250, 350 Zeng et al (2010) A finite-sized stationary particle in a channel flow of modest turbulence 40 ∼ 450 Lucci et al (2010) Finite-sized solid spherical particles in decaying isotropic turbulence O (10) (65/75/280) Belt et al (2012) Particle-laden secondary flow in turbulent pipe flows 110, 217 Xu and Bodenschatz (2008) Particles in intense turbulent water flows 22, 35, 55 Kidanemariam et al (2013) Horizontal open channel flow with finite-size, heavy particles 15 ∼ 20 Laín and Sommerfeld (2012) Pneumatic conveying of spherical particles in horizontal ducts 40 Dorgan and Loth (2004) Particles released near the wall in a turbulent boundary layer 10 −5 ∼ 30 Zeng et al (2008) Turbulent channel flow over an isolated particle of finite-size 42 ∼ 295, 325/455 Tenneti and Subramaniam (2014) Gas-solid flows 20, 50 Wang et al (2008) Sedimentation of 1, 2 or 105 particles in a channel flow about 17.3, 503 García-Villalba et al (2012) Vertical plane channel flow with finite-size particles 132 Uhlmann (2008) Vertical particulate channel flow 136 Uhlmann and Doychev (2014) The gravity-induced motion of randomly distributed, finite-size, heavy particles in quiescent fluid in triply periodic domains ing on a sphere near the wall and experimentally study translational and rotational motion of a particle slightly heavier than the fluid in a rotating drum filled with water. Lin and Lin (2013) numerically studied the effects of finite particle Reynolds numbers up to Re p = 50 on the model for normal lubrication force on a particle moving towards a solid wall using the immersed boundary method.…”

Section: Referencesmentioning

confidence: 99%

“…The wall-bounded particle-fluid two-phase flows exist widely in numerous industrial and natural processes, such as the solidfluid flow in industrial pneumatic conveying ( Laín and Sommerfeld, 2012 ), the flows in a pump, the flows in fluidized bed ( Capecelatro et al, 2014;Lu et al, 2013 ), sediment deposition and transport in rivers ( Kidanemariam et al, 2013 ). One of the crucial phenomena in such flows is the interaction between particles and a solid wall.…”

Section: Introductionmentioning

confidence: 99%

“…Zeng et al ( 2008; considered the turbulent channel flow over an isolated particle with variable sizes and locations. There are also pipe flows laden with particles, such as the experimental study of turbulent flow driven by particles in pipe flows ( Belt et al, 2012 ) and the gassolid flows in wall-bounded vertical risers ( Laín and Sommerfeld, 2012;Lu et al, 2013;Wang et al, 2013 ). In addition, Lucci et al (2010) numerically simulated the turbulent flow around moving spherical particles dispersed in a decaying isotropic turbulent flow.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Hydrodynamic force and torque models for a particle moving near a wall at finite particle Reynolds numbers

Zhou

Jin

Tian

et al. 2017

International Journal of Multiphase Flow

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: Models for hydrodynamic force and torque Finite particle Reynolds number Near-wall effect Particle-resolved simulation Sub-grid scale model Eulerian-Lagrangian simulation a b s t r a c t This research work is aimed at proposing models for the hydrodynamic force and torque experienced by a spherical particle moving near a solid wall in a viscous fluid at finite particle Reynolds numbers. Conventional lubrication theory was developed based on the theory of Stokes flow around the particle at vanishing particle Reynolds number. In order to account for the effects of finite particle Reynolds number on the models for hydrodynamic force and torque near a wall, we use four types of simple motions at different particle Reynolds numbers. Using the lattice Boltzmann method and considering the moving boundary conditions, we fully resolve the flow field near the particle and obtain the models for hydrodynamic force and torque as functions of particle Reynolds number and the dimensionless gap between the particle and the wall. The resolution is up to 50 grids per particle diameter. After comparing numerical results of the coefficients with conventional results based on Stokes flow, we propose new models for hydrodynamic force and torque at different particle Reynolds numbers. It is shown that the particle Reynolds number has a significant impact on the models for hydrodynamic force and torque. Furthermore, the models are validated against general motions of a particle and available modeling results from literature. The proposed models could be used as sub-grid scale models where the flows between particle and wall can not be fully resolved, or be used in Lagrangian simulations of particle-laden flows when particles are close to a wall instead of the currently used models for an isolated particle.

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Numerical calculation of pneumatic conveying in horizontal channels and pipes: Detailed analysis of conveying behaviour

Cited by 80 publications

References 28 publications

Numerical analysis of sprays with an advanced collision model

Numerical analysis of sprays with an advanced collision model

The effects of wall roughness on erosion rate in gas–solid turbulent annular pipe flow

Hydrodynamic force and torque models for a particle moving near a wall at finite particle Reynolds numbers

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