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| Hydrogen Embrittlement of Sensors (ChatGPT) |
| Short Course on Advanced Propulsion Systems |
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Short Course on Advanced Propulsion Systems
Amardip Ghosh #Member Profile
Day 1 – Ramjet and Scramjet
Morning – Ramjet Engines
Overview and Applications:
- Flight regimes, where ramjets excel
- Historical context: V-1, Meteor missile, BrahMos
Thermodynamic Cycle:
- Constant pressure (Brayton) cycle
- Rayleigh line for subsonic combustion
- Ideal performance and limits
Flow Physics and Components:
- Intake design (supersonic → subsonic diffusion)
- Combustor design for subsonic combustion
- Nozzle expansion
- Effect of area change, friction, and heat addition (Shapiro influence coefficients)
Unsteady Phenomena:
- Intake buzz, overspeed Mach number
- Start/unstart
Diagnostics and Visualization:
- Schlieren for intake shocks
- Pressure and temperature measurements
Late Morning – RAM Accelerators
Concept and Operating Principle:
- Projectile inside a stationary tube filled with fuel–oxidizer mixture
- Analogy to an in-tube ramjet combustion process
Modes of Operation:
- Sub-detonative mode – combustion behind projectile at sub-detonation speeds
- Super-detonative mode – projectile speed exceeds CJ detonation velocity
Thermodynamic Considerations:
- Rayleigh line and Hugoniot analysis for sub- vs super-detonative cases
- Pressure–temperature–velocity relationships
Applications:
- Hypervelocity projectile research
- Launch assist systems for orbital payloads
Diagnostics:
- High-speed schlieren, chemiluminescence
- Projectile tracking via magnetic pickup or laser diagnostics
Afternoon – Scramjet Engines
Overview and Applications:
- Flight regimes (Mach 5 )
- Vehicle integration (forebody compression, cowl lip placement)
- Programs: X-43, X-51
Thermodynamic Cycle:
- Rayleigh line for supersonic combustion
- Heat addition effects in supersonic flow
- Thermal choking
Flow and Mixing Physics:
- Supersonic mixing challenges
- Fuel injection and flame stabilization (cavity, strut, pylon)
Engine Components:
- Supersonic/hypersonic intakes
- Isolator – role, combustor–isolator coupling, scaling
- Nozzle designs for hypersonics
Unsteady Phenomena:
- Combustion–acoustic coupling
- Oscillations in scramjet combustors
- Mode transition (ramjet → scramjet)
- Unstart, restart
Diagnostics and Visualization:
- Schlieren and chemiluminescence imaging
- High-speed pressure and temperature sensing
- Ion probes for high-enthalpy flows
Day 2 – Detonation-Based Engines and Combined Cycles
Morning – Detonation Fundamentals
Deflagration vs Detonation:
- Rankine–Hugoniot and Rayleigh line for detonations
- Chapman–Jouguet velocity, overdriven detonations
- ZND detonation structure
PDE vs RDE:
- PDE: constant-volume combustion
- RDE: continuous detonation in annular chamber
- Flow path and wave structure differences
Midday – Rotating Detonation Engines (RDE)
Thermodynamic Cycle:
- Humphrey cycle and detonation cycle efficiency
Flow Physics:
- Detonation wave propagation in annular chambers
- Mixing and injection strategies
- Overdriven and underdriven regimes
Components:
- Injector design for continuous detonation
- Chamber geometry effects
- Nozzle integration
Unsteady Phenomena:
- Wave number selection
- Coupling between injection, detonation, and exhaust
Diagnostics:
- High-speed schlieren of detonation fronts
- Chemiluminescence for reaction zone imaging
- Fast ion probes and pressure transducers
Afternoon – Combined Cycle Engines
Turbojet–Ramjet Combined Cycle:
- Turbine-based propulsion up to Mach ~3
- Transition to ramjet at higher Mach numbers
- Intake and nozzle geometry adjustments
Ramjet–Scramjet Combined Cycle:
- Dual-mode scramjets (subsonic to supersonic combustion)
- Mode transition management and stability
Turbojet–Ramjet–Scramjet Combined Cycle:
- Integration strategy: turbine in front of ram/scram duct
- Variable geometry inlets/nozzles
- Thermal management and bypass flows
RBCC and TBCC Architectures:
- Rocket-based combined cycle for space access
- Turbine-based combined cycle for reusable hypersonic aircraft
Challenges:
- Mass and volume penalties
- Control of transitions between modes
- Material limits and cooling systems
Case Studies:
- SR-71 (turbo–ram transition)
- NASA GTX, Japanese ATREX, Hypersonic air-breathing access-to-space concepts
Wrap-Up
Comparative performance map: Ramjet vs Scramjet vs RDE vs RAM Accelerator
Open research challenges
Future trends: detonation-based combined cycles, hybrid air–space propulsion