Turbulent gas‐particle flow in vertical risers

Dasgupta, Sanjay; Jackson, R.; Sundaresan, Sankaran

doi:10.1002/aic.690400204

Cited by 138 publications

(102 citation statements)

References 36 publications

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“…On the other hand, if 2 c is large, the gas is expected to play a dominant role in the fluid fluctuating motion of particles. So, for very dilute gas-solid two-phase flows, 2 c is expected to be very large ͑ 2 c → ϱ ͒. The turbulent eddy viscosity in particle phase for the dilute mixtures is further simplified as…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…1,2 Turbulence enhances the momentum, heat, and mass transfer between the dispersed phase and the carrier phase. Our focus is on solid suspensions that are low in volume fraction, but which still have relatively high mass loading due to high thermodynamic density of the particles.…”

Section: Introductionmentioning

confidence: 99%

“…It has been tested by other researchers, 10 and compared with experimental results for turbulent gas-solid flows in a vertical pipe, 1 and in a vertical riser. 2 Eulerian-Eulerian ͑EE͒ models, such as those described here, are used in CFD codes for simulating multiphase flows in engineering applications. Typical applications include design and scaleup of circulating fluidized combustors and coal gasifiers.…”

Section: Introductionmentioning

confidence: 99%

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A multiscale model for dilute turbulent gas-particle flows based on the equilibration of energy concept

Subramaniam

2006

Physics of Fluids

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The objective of this study is to improve Eulerian-Eulerian models of particle-laden turbulent flow. We begin by understanding the behavior of two existing models-one proposed by Simonin [von Kármán Institute of Fluid Dynamics Lecture Series, 1996], and the other by Ahmadi [Int. J. Multiphase Flow16, 323 (1990)]-in the limiting case of statistically homogeneous particle-laden turbulent flow. The decay of particle-phase and fluid-phase turbulent kinetic energy (TKE) is compared with direct numerical simulation results. Even this simple flow poses a significant challenge to current models, which have difficulty reproducing important physical phenomena such as the variation of turbulent kinetic energy decay with increasing particle Stokes number. The model for the interphase TKE transfer time scale is identified as one source of this difficulty. A new model for the interphase transfer time scale is proposed that accounts for the interaction of particles with a range of fluid turbulence scales. A new multiphase turbulence model-the equilibration of energy model (EEM)-is proposed, which incorporates this multiscale interphase transfer time scale. The model for Reynolds stress in both fluid and particle phases is derived in this work. The new EEM model is validated in decaying homogeneous particle-laden turbulence, and in particle-laden homogeneous shear flow. The particle and fluid TKE evolution predicted by the EEM model correctly reproduce the trends with important nondimensional parameters, such as particle Stokes number. The objective of this study is to improve Eulerian-Eulerian models of particle-laden turbulent flow. We begin by understanding the behavior of two existing models-one proposed by Simonin ͓von Kármán Institute of Fluid Dynamics Lecture Series, 1996͔, and the other by Ahmadi ͓Int. J. Multiphase Flow 16, 323 ͑1990͔͒-in the limiting case of statistically homogeneous particle-laden turbulent flow. The decay of particle-phase and fluid-phase turbulent kinetic energy ͑TKE͒ is compared with direct numerical simulation results. Even this simple flow poses a significant challenge to current models, which have difficulty reproducing important physical phenomena such as the variation of turbulent kinetic energy decay with increasing particle Stokes number. The model for the interphase TKE transfer time scale is identified as one source of this difficulty. A new model for the interphase transfer time scale is proposed that accounts for the interaction of particles with a range of fluid turbulence scales. A new multiphase turbulence model-the equilibration of energy model ͑EEM͒-is proposed, which incorporates this multiscale interphase transfer time scale. The model for Reynolds stress in both fluid and particle phases is derived in this work. The new EEM model is validated in decaying homogeneous particle-laden turbulence, and in particle-laden homogeneous shear flow. The particle and fluid TKE evolution predicted by the EEM model correctly reproduce the trends with important nondimensional parameter...

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Section: Acknowledgmentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A multiscale model for dilute turbulent gas-particle flows based on the equilibration of energy concept

Subramaniam

2006

Physics of Fluids

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“…Thus, the rheologic properties of particles, the solid phase pressure, viscosity of particles, conductive energy flux, and dissipation are considered as a function of granular temperature. Simulations using kinetic theory of granular flow have been reported by many researchers in gas-particle fluidization [7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In KFGT, the particle flow is assumed to be laminar flows instead of large-scale turbulent flows.…”

Section: Introductionmentioning

confidence: 99%

Particle Dispersion Behaviors of Dense Gas-Particle Flows in Bubble Fluidized Bed

2013

Advances in Mechanical Engineering

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An Euler-Euler two-fluid model incorporating a developed momentum transfer empirical coefficient is developed to study the particle dispersion behaviors of dense gas-particle flows in gas-fluidization reactor. In this model, the four-way couplings among gas-particles, particle-gas, and particle-particle collisions are fully considered based on kinetic theory of granular flows and an improved smooth continuous drag coefficient is utilized. Gas turbulent flow is solved by large eddy simulation. The particle fraction, the time-averaged axial particle velocity, the histogram of particle fluctuation velocity, and the wavelet analysis of pressure signals are obtained. The results are in good agreement with experimental measurements. The mean value and the variance of axial particle velocity are greater than those of radial particle velocities. Particle collision frequencies at bubble vibrant movement regions along axial direction are much higher than those of radial direction and attenuated along height increase. Low-frequency component of pressure signal indicating the bubble movement behaviors in the center of reactor is stronger than wall regions. Furthermore, the negative values represent the passed bubble and positive peak values disclose the continuous motion of single bubble.

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“…Louge, Mastorakos & Jenkins, 1991;Dasgupta, Sundaresan & Jackson, 1994;Bolio, Yasuna & Sinclair, 1995;Boëlle, Balzer, and Simonin, 1995). Collisions between such particles can transfer a significant amount of momentum within the flow and at the boundaries.…”

Section: Introductionmentioning

confidence: 99%

Studies of gas-particle interactions in a microgravity flow cell

Louge

Xu²,

Jenkins³

et al. 2000

AIP Conference Proceedings

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Abstract. We are developing a microgravity flow cell in which to study the interaction of a flowing gas with relatively massive particles that collide with each other and with the moving boundaries of the cell. Unlike Earth-bound flows where the gas velocity must be set to a value large enough to defeat the weight of particles, the duration and quality of microgravity on the Space Station will permit us to achieve suspensions where the agitation of the particles and the gas flow can be controlled independently by adjusting the pressure gradient along the flow and the relative motion of the boundaries. This paper describes the experimental apparatus, outlines a theory and computer simulations to predict the flow, and specifies microgravity requirements for its implementation in Space.

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Turbulent gas‐particle flow in vertical risers

Cited by 138 publications

References 36 publications

A multiscale model for dilute turbulent gas-particle flows based on the equilibration of energy concept

A multiscale model for dilute turbulent gas-particle flows based on the equilibration of energy concept

Particle Dispersion Behaviors of Dense Gas-Particle Flows in Bubble Fluidized Bed

Studies of gas-particle interactions in a microgravity flow cell

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