Scramjet Combustion explores the development of a high-speed scramjet engine operating in the supersonic/hypersonic range for various air and space transport applications. The book explains the basic structure, components, working cycle, and the relevant governing equations in a clear manner that speaks to both advanced and more novice audiences. Particular attention is paid to efficient air–fuel combustion, looking at both the underlying fundamentals of combustion as well strategies for obtaining optimum combustion efficiency. Methods for reaching the chemically correct air–fuel ratio, subsequent flame, and combustion stabilization as air enters at supersonic speed are also outlined. Further, it includes the continuous on-going efforts, innovations, and advances with respect to the design modification of scramjet combustors, as well as different strategies of fuel injections for obtaining augmented performance while highlighting the current and future challenges.
Author(s): Gautam Choubey, Manvendra Tiwari
Publisher: Butterworth-Heinemann
Year: 2022
Language: English
Pages: 197
City: Oxford
Front Cover
Scramjet Combustion: Fundamentals and Advances
Copyright
Contents
Acknowledgements
Chapter One: Introduction
1.1. Background and motivation
1.2. A brief history at a glance
1.3. The basic structure and layout of a scramjet engine
1.4. Challenges faced by a scramjet engine during supersonic combustion
1.5. Strategies for combating combustion difficulties
1.6. Fuel injectors for scramjet engines
1.6.1. Wall injection
1.6.2. Wall injection with cavity
1.6.3. Ramp injection
1.6.4. Strut injection
1.7. Working cycle
1.8. Governing equations
1.8.1. Conservation of mass
1.8.2. Conservation of momentum
1.8.3. Conservation of energy
1.8.4. Conservation of species
1.8.5. Equations of state
1.8.6. Fouriers law of heat transfer
1.8.7. The shear stress
References
Chapter Two: Scramjet combustion mechanism
2.1. Introduction
2.2. Chemical kinetics in supersonic flow
2.2.1. Reaction mechanisms of hydrogen-air
2.2.2. Hydrogen-air combustion with reduced mechanisms
2.2.3. Hydrocarbon reaction mechanisms
2.3. Basic terms related to supersonic combustion
2.3.1. Equivalence ratio
2.3.2. The Arrhenius law
2.3.3. Combustion performances
2.3.3.1. Combustion efficiency
2.3.3.2. Mixing efficiency
2.3.3.3. Total pressure loss
2.3.3.4. Penetration height
2.4. Fuels used in supersonic combustion
2.4.1. Why H2 fuel?
2.4.2. Challenges encountered by H2 fuel
2.5. Strategies for fuel-air mixing
2.5.1. Roadmap for effective mixing
2.5.1.1. Active approaches for mixing augmentation
2.5.1.2. Passive flow control methods
2.5.1.3. Shock wave-induced mixing enhancement
2.5.2. Estimate of the degree of mixing
2.6. Turbulent combustion
References
Chapter Three: Factors affecting the scramjet performance
3.1. Introduction
3.2. Potential flame holders
3.3. Combustion stabilization in a strut-based scramjet combustor
3.3.1. Fuel ignition delay
3.3.2. Primary ignition strategies
3.3.3. Criteria for flame stabilization
3.3.4. The characteristics of flame in strut-based scramjet combustors
3.4. Flame propagation mechanism
3.4.1. The characteristics of flame flashback during flame propagation
3.4.2. Ram-scram transition in a scramjet combustor triggered by flame propagation
3.5. Wall-mounted cavity-stabilized combustion
References
Chapter Four: Advances in scramjet fuel injection technology
4.1. Strut injection
4.1.1. Influence of the strut layout on the performance of a scramjet combustor
4.1.2. The multi-strut fuel injection scheme
4.1.3. Strut + cavity injection strategy
4.1.4. Strut + wall injection strategy
4.2. Ramp injection
4.3. Cavity injection approach
4.3.1. Cavity as a flame holder and its effect on fuel injection as well as supersonic mixing
4.3.1.1. Upstream injection
4.3.1.2. Floor injection
4.3.1.3. Parallel injection
4.3.2. Reacting flow field
4.3.2.1. Upstream injection
4.3.2.2. Floor injection
4.3.2.3. Parallel injection
4.3.3. Stability limits
4.3.4. Oscillation phenomena in cavity-based combustion
4.3.5. Current advancements in dual-cavity/double-cavity scramjets
4.4. The transverse injection approach
4.4.1. The multi-port injection strategy
4.4.2. Inclusion of a vortex generator in transverse injection
4.5. Emerging ramjet technologies
4.5.1. Shock-induced combustion ramjet (shcramjet) engines
4.5.2. Oblique detonation wave (ODW) engines
4.5.3. Rocket-based combined cycle (RBCC) engines
References
Chapter Five: Roadmap for future research
5.1. Challenges for strut designs
5.2. Issues related to cavity-based injection
5.3. Future research strategies in the direction of the transverse injection technique
Chapter Six: Pedagogy for the computational approach in simulating supersonic flows
6.1. Turbulence modelling in scramjet flows
6.1.1. Reynolds and Favre averaging
6.1.2. The standard k-ε model
6.1.3. The RNG k-ε model
6.1.4. The SST k-ω turbulence model
6.1.5. The LES turbulence model
6.2. Computational approach to model a single strut-based scramjet combustor
6.2.1. Geometry and mesh specification
6.2.2. Generation of mesh and mesh refinement study
6.3. Numerical modelling and simulation details
6.3.1. Governing equations
6.3.2. Combustion modelling
6.3.3. Boundary conditions
Assumptions
6.4. Validation study for a single-strut scramjet combustor
References
Index
Back Cover
