Theory and Modeling of Dispersed Multiphase Turbulent Reacting Flows

Lixing Zhou

• Publisher: Butterworth-Heinemann
• Year: 2018
• Print ISBN: 9780128134658
• eBook ISBN: 9780128134665
• Topic: Technology & Engineering
• Subtopic: Physics
• Index: Physics

Theory and Modeling of Dispersed Multiphase Turbulent Reacting Flows gives a systematic account of the fundamentals of multiphase flows, turbulent flows and combustion theory. It presents the latest advances of models and theories in the field of dispersed multiphase turbulent reacting flow, covering basic equations of multiphase turbulent reacting flows, modeling of turbulent flows, modeling of multiphase turbulent flows, modeling of turbulent combusting flows, and numerical methods for simulation of multiphase turbulent reacting flows, etc. The book is ideal for graduated students, researchers and engineers in many disciplines in power and mechanical engineering.- Provides a combination of multiphase fluid dynamics, turbulence theory and combustion theory- Covers physical phenomena, numerical modeling theory and methods, and their applications- Presents applications in a wide range of engineering facilities, such as utility and industrial furnaces, gas-turbine and rocket engines, internal combustion engines, chemical reactors, and cyclone separators, etc.

Chapter 1

Some Fundamentals of Dispersed Multiphase Flows

Abstract

To simulate dispersed multiphase turbulent reacting flows, at first it is necessary to understand some fundamentals of dispersed multiphase flows. This chapter gives some knowledge in this aspect, as particle/droplet size and its distribution, apparent density and volume fraction, particle drag and heat and mass transfer, and single-particle dynamics.

Keywords

particle size; particle apparent density; particle volume fraction; particle drag; particle mass and heat transfer; particle dynamics

1.1 Particle/Spray Basic Properties

To characterize gas-particle or gas-spray flows, it is necessary first to describe the particle/spray basic properties [1–4] as follows.

1.1.1 Particle/Droplet Size and Its Distribution

The particle/droplet size distribution is frequently expressed by the semiempirical Rosin–Rammler formula as:

$R(d_k)=\exp [-{(d_k/\overline{d})}^n]$ (1.1)

(1.1)

where R(d_k) is the weight fraction of particles with sizes larger than d_k, n is the index of nonuniformness, and $\overline{d}$

is a characteristic size. Both n and $\overline{d}$

are determined by experiments. The derivative of R(d_k) is

${\displaystyle \frac{dR}{d(d_k)}}=n{(d_k)}^{n-1}{(\overline{d})}^{-n}\exp [-{(d_k/\overline{d})}^n]$ (1.2)

(1.2)

which expresses the differential particle size distribution, and R(d_k) is the integral size distribution. The mean particle sizes can be defined as:

$\begin{array}{l}{d}_{10}=\sum n_k{d}_k/\sum n_k\hfill \\ d_{20}={(\sum n_k{d}_k^2/\sum n_k)}^{1/2}\hfill \\ d_{30}={(\sum n_k{d}_k^3/\sum n_k)}^{1/3}\hfill \\ d_{32}={\sum n}_k{d}_k^3/({\sum n}_k{d}_k^2)\hfill \end{array}$ (1.3)

(1.3)

where $d_{10},d_{20},d_{30},\mathrm{and}{d}_{32}$

are diameter-averaged, surface-averaged, volume-averaged, and Sauter mean sizes, respectively. The Sauter diameter is most widely used in engineering. The typical particle sizes are:

Coal particles in fluidized beds	1–10 mm
Liquid spray	10–200 μm
Pulverized coal	1–100 μm
Soot particles	1–5 μm

1.1.2 Apparent Density and Volume Fraction

For gas-particle/dr...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• Nomenclature
• Introduction
• Chapter 1. Some Fundamentals of Dispersed Multiphase Flows
• Chapter 2. Basic Concepts and Description of Turbulence
• Chapter 3. Fundamentals of Combustion Theory
• Chapter 4. Basic Equations of Multiphase Turbulent Reacting Flows
• Chapter 5. Modeling of Single-Phase Turbulence
• Chapter 6. Modeling of Dispersed Multiphase Turbulent Flows
• Chapter 7. Modeling of Turbulent Combustion
• Chapter 8. The Solution Procedure for Modeling Multiphase Turbulent Reacting Flows
• Chapter 9. Simulation of Flows and Combustion in Practical Fluid Machines, Combustors, and Furnaces
• Index