Turbulence modelling for gas-particle flows

Mohit P. Tandon1, Meera Gupta2 and Aditya Karnik1

1 CD-adapco, India, 2 IIT-Delhi , India

Outline

• An effort to understand the role of Particle Phase Turbulence

• Focus Applications: Downers and Risers

• Experimental Data: Lateral Segregation in Volume Fraction

Background

• Fox (2014)# stressed on the need to separate between turbulent

kinetic energy and granular energy of particles

Individual Particle

Scale Cluster Scale

Fluctuations associated

with granular

temperature

Fluctuations associated

with turbulent kinetic energy

# Fox, R.O. On multiphase turbulence models for collisional fluid-particle flows, JFM (742), 2014

• Volume Fraction

• Momentum

Turbulent Dispersion Force

Governing Equations: Particle Phase

s

• Granular Temperature

• Turbulent Kinetic Energy

Governing Equations: Particle Phase

Interphase

Turbulence Exchange

Governing Equations: Fluid Phase

• Turbulent Kinetic Energy

Turbulence induced due to the presence of particles

Downer

• Experimental Details#

– Co-current down flow – Height of Column: 7 m – Diameter of Column: 0.14 m – Density of Particles: 1545 Kg/m3 – Diameter of Particles: 54 μm – Density of Gas: 1.18 Kg/m3 – Gas Viscosity: 1.8 e-5 Pas – Superficial Gas Velocity: 4.33 m/s – Inlet Solid Flow Rate: 70 Kg/m

2-s

g

Inlet for gas & particles

# Wang et al. Powder Technology (70), 1992, 271-275

Downer

• Problem Set-up – Mesh: 70x70 – Radial Distribution Function: Ding-Gidaspow – Particle Viscosity: Gidaspow – Granular Conductivity: Gidaspow – Drag Model: Wen and Yu – Wall treatment: No-slip for gas and Slip for particles

Downer: Results

Simulation without considering particle phase turbulence

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0 0.2 0.4 0.6 0.8 1 1.2

Experimental

Simulation

r/R

Vo

lum

e F

ractio

n o

f P

art

icle

Lateral distribution of the particles

Downer: Results

Simulation with particle phase turbulence – no exchange

r/R

Vo

lum

e F

ractio

n o

f P

art

icle

Lateral distribution of the particles

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0 0.2 0.4 0.6 0.8 1 1.2

Experimental

Simulation A

Simulation B

Downer: Results

Simulation with particle phase turbulence – exchange accounted

r/R

Vo

lum

e F

ractio

n o

f P

art

icle

Lateral distribution of the particles

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0 0.2 0.4 0.6 0.8 1 1.2

Experimental

Simulation A

Simulation B

Simulation C

Downer: Turbulent Kinetic Energy Exchange

Particle Phase:

Fluid Phase:

Net Dissipation of Turbulent Kinetic Energy

Downer: Turbulent Kinetic Energy Exchange

Downer: Turbulent Kinetic Energy Exchange

Particle Thermal

Energy

Turbulent Kinetic

Energy Gas Mean Kinetic

Energy Gas

Turbulent Kinetic

Energy Particle

Mean

Shear

Inter Phase

Turbulent

Exchange

Mean Kinetic

Energy Particle Mean

Shear

Drag

Buoyancy

Granular

Temperature

ℇp e Collisions

Gas Thermal

Energy

ℇf Heat

Transfer

Energy Flow Diagram

Downers: Parametric Study for beta

Lateral distribution of the particles

Downers: Parametric Study for restitution coefficient

Lateral distribution of the particles

Downers: Scale up investigation

Lateral distribution of the particles

Riser

• Experimental Details

– Circulating Fluidized Bed – Density of Gas: 1.18 Kg/m3 – Gas Viscosity: 1.8 e-5 Pas – Superficial Gas Velocity: 1.29 m/s – Inlet Solid Flow Rate: 11.71 Kg/m

2-s

• Problem Set-up – Mesh: 80x430 – Radial Distribution Function: Ding-Gidaspow – Particle Viscosity: Syamlal – Granular Conductivity: Syamlal – Drag Model: EMMS – Wall treatment: No-slip for gas and Slip for particles

Riser: Results

r/R

Vo

lum

e F

ractio

n o

f P

art

icle

Lateral distribution of the particles at z/D = 1.06

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0 0.2 0.4 0.6 0.8 1

Experimental

Turbulence

Laminar

Thank You!