Stabilization and Dynamic of Premixed Swirling Flames: Prevaporized, Stratified, Partially, and Fully Premixed Regimes

Cover
STABILIZATION AND
DYNAMIC OF
PREMIXED SWIRLING
FLAMES
Prevaporized, Stratified,
Partially, and Fully Premixed
Regimes
Copyright
Dedication
Contents
Preface
Introduction
	Environmental footprint
	Acoustic footprint
	Economical and technical challenges
1 The combustor
	1 Overall principle of the gas turbine engine
		1.1 Generalities and overall description
			1.1.1 Propulsion versus power generation
				Propulsion systems
				Power generation systems
			1.1.2 Turboprop
			1.1.3 Turbojet
			1.1.4 Turbofan
			1.1.5 Turboshaft and land-based gas turbine
		1.2 Component/module technology descriptions
			1.2.1 Intake and fan
			1.2.2 Compressor
			1.2.3 Combustor
			1.2.4 Turbine
			1.2.5 Exhaust nozzle
		1.3 Thermodynamics and nonreacting fluid dynamics
			1.3.1 Thermodynamic formalism
			1.3.2 Nonreacting fluid dynamics formalism
			1.3.3 Overall cycle and component efficiencies
			1.3.4 Components design, challenges, and future trends
	2 Combustor role, requirements, and environment
		2.1 Overall view
		2.2 Design and requirements
		2.3 Combustor, injector, and swirler designs
			2.3.1 Gas turbine combustor requirements and combustion modes
			2.3.2 Combustor physics
			2.3.3 Combustor design
			2.3.4 Design of injector's swirler
	3 Combustor architectures
		3.1 Rich-burn quick-quench lean-burn
		3.2 Lean direct injection
		3.3 Lean premixed/prevaporized
		3.4 Low swirl injector
		3.5 Lean fully premixed
	4 Operating conditions and flight envelope
2 Premixed combustion for combustors
	1 Mathematical descriptions
		1.1 Governing equations of reacting flows
			1.1.1 Equivalence ratio
			1.1.2 Equilibrium composition
			1.1.3 Adiabatic flame temperature
		1.2 G-equation formalism
	2 Physical-chemical description
		2.1 Premixed combustion overview
		2.2 Swirling flames overview
		2.3 Acoustic wave-flame interactions
		2.4 Autoignition
		2.5 Blowout
		2.6 Chemical kinetics
		2.7 Combustion noise
		2.8 Combustion instability
		2.9 Flame speed
		2.10 Flame stretch
		2.11 Flammability limits
		2.12 Flashback
		2.13 Ignition
		2.14 Pollutant emissions
		2.15 Turbulent combustion
		2.16 Turbulent mixing
	3 Combustion modes
		3.1 Overview
		3.2 Prevaporized mode
		3.3 Partially premixed mode
		3.4 Stratified premixed mode
		3.5 Fully premixed mode
	4 Effects of operating conditions on premixed combustion and the flame
		4.1 Current operating conditions
		4.2 Fuel, equivalence ratio, and power settings engine matching
3 Premixed swirling flame stabilization
	1 Mechanisms and processes of stabilization
		1.1 Definitions
		1.2 Key stabilization mechanisms: local contributors
		1.3 Local equivalence ratio
		1.4 Flame stretch
		1.5 Flame speed versus flow speed
		1.6 Reaction rates
		1.7 Vorticity
		1.8 Temperature, pressure, and density (equation of state)
		1.9 Governing equations
		1.10 Role and impact of global flow/flame features
	2 Framework for flame stabilization study: application
		2.1 Numerical procedure
		2.2 Statistically steady flame dynamics
			2.2.1 Reacting flowfield description
			2.2.2 Local contributor fields
			2.2.3 Local contributors' distributions
			2.2.4 Flame stabilization mechanism descriptions
			2.2.5 Summary
	3 Theoretical results on flame stabilization and propagation
		3.1 Flowfield decomposition and theoretical approach: framework
		3.2 Regimes and configurations
		3.3 Expressions for laminar and turbulent planar flames in open tubes
			3.3.1 Laminar flame propagating in an open tube
			3.3.2 Turbulent flame propagating in an open tube
		3.4 Expressions for the static component of stabilized flames
		3.5 Expressions for the dynamic component of stabilized flames
			3.5.1 Canonical form
			3.5.2 Expression for turbulent stabilized flames
			3.5.3 Expression for modulated stabilized flames
			3.5.4 Mathematical-physical description
		3.6 Swirling flame numerical simulations: results and discussion
		3.7 Summary
	4 Effects of operating conditions, swirl number, and fuel on flame stabilization
4 Transient combustion
	1 Introduction
		1.1 Definitions
		1.2 Data sciences and data analysis
		1.3 Measurements and diagnostics
	2 Unsteady premixed combustion
		2.1 Laminar unsteady premixed combustion
			2.1.1 Strained and curved flames
			2.1.2 Flames submitted to flow modulation
			2.1.3 Laminar combustion studies and DNS modeling relevant for turbulent combustion
		2.2 Turbulent premixed combustion
	3 Combustor engine transient
	4 Configuration case study
		4.1 Methodology and numerical procedure
		4.2 Time-average versus instantaneous velocity field
		4.3 Flashback
		4.4 Lean blowout
			4.4.1 Introduction
			4.4.2 Results and comparison with experiment
				Velocity field and flame shape
				Transient sequence toward LBO
			4.4.3 LBO physical mechanisms understanding
				Observations
				Mechanistic description
			4.4.4 Conclusions
		4.5 Transient to limit cycle
			4.5.1 Longitudinal mode
			4.5.2 Transversal mode
	5 Fundamental mechanisms and link between steady and unsteady combustion
		5.1 Static and dynamic stability link
		5.2 Static stability
		5.3 Dynamic stability
	6 Technologies and control for flame stabilization and combustion instability
		6.1 State of the art
			6.1.1 Laminar flames
			6.1.2 Turbulent flames
			6.1.3 Control methods for flame stabilization
			6.1.4 Control methods for combustion instability
		6.2 Effects of swirler position
		6.3 Effects of geometry
		6.4 Effects of operating conditions, equivalence ratio, and fuel
5 Swirling flame dynamics and combustion instability
	1 Combustor acoustics
		1.1 Combustion instability loops
		1.2 Network acoustics model
		1.3 Acoustics codes
		1.4 Upstream flow modulation versus self-sustained oscillations
		1.5 Flow modulation and Navier-Stokes characteristic boundary condition models
	2 Modulated swirling flame dynamics
		2.1 Flame responses
			2.1.1 Experiments
			2.1.2 Numerical simulations
			2.1.3 Theoretical transfer function
		2.2 Flow dynamic mode conversion processes occurring upstream of the flame
			2.2.1 Observations from experiments and numerical simulations
			2.2.2 Theoretical results
			2.2.3 Summary
		2.3 Unsteady flame front dynamics
		2.4 Combustion dynamics mechanisms
			2.4.1 Swirl number, flame angle, and turbulent flame speed oscillations
			2.4.2 Vortex roll-up and flame surface modulation
			2.4.3 Other elements of the literature
	3 Combustion instability
		3.1 Combustion instability prediction
			3.1.1 Predictive methods
			3.1.2 Stability map
			3.1.3 Frequency-growth rate trajectories
		3.2 Coupling and stability criteria
		3.3 Longitudinal instabilities
			3.3.1 Velocity coupling
			3.3.2 Equivalence ratio coupling
			3.3.3 Entropy modes
		3.4 Tangential instabilities
			3.4.1 Experimental results
			3.4.2 Numerical simulations
			3.4.3 Theory
6 Design and numerical simulation modeling
	1 Context and challenges
	2 Modeling of flow modulations in numerical simulations
		2.1 Introduction
		2.2 Combustor dynamics modulation models
			2.2.1 Navier-Stokes characteristic boundary conditions
			2.2.2 Inlet velocity modulation
			2.2.3 Inlet wave modulation
		2.3 Inlet modulation in an isothermal duct
			2.3.1 Verification with analytical solution
			2.3.2 Analytical solutions for verification
				Traveling wave
				Standing wave IVM
				Standing wave IWM
			2.3.3 Comparison between IVM and IWM
		2.4 Application to a bluff-body-stabilized flame
		2.5 Conclusions
	3 Modeling approaches and assumptions
		3.1 Unsteady Reynolds-averaged Navier-Stokes
		3.2 Large eddy simulations
	4 Chemical kinetics
	5 Turbulent combustion modeling
		5.1 Thickened flame models
		5.2 Flamelet models
		5.3 Flame surface models
		5.4 Probability density function models
	6 A priori filtering for turbulent combustion models
		6.1 Introduction
		6.2 The a priori filtering method
		6.3 DNS Preccinsta data set
			6.3.1 Governing equations
			6.3.2 Variables, geometry, and operating conditions
			6.3.3 Reconstructed variables
		6.4 Results and discussion
			6.4.1 Density, temperature, and mass fraction ratio
			6.4.2 Flame structure
			6.4.3 Flame speed
			6.4.4 Index
		6.5 Comparisons for the thickened flame model
		6.6 Conclusions and perspectives
	7 Fuel vaporization physics and modeling
	8 Supercritical combustion regime at take-off conditions
7 Lean fully premixed injector design
	1 Design procedure
	2 Innovation and concept definition
	3 Modeling and sizing
		3.1 Vaporizing unit
		3.2 Premixing and premixing-stabilizing units
	4 Conclusion
Conclusion and perspectives
References
Index
Back Cover