The document discusses the principles and operation of ramjet engines. A ramjet relies on forward air compression through the engine intake to generate thrust, requiring high-speed flight. It has no moving parts for compression. Air entering the intake is slowed in a supersonic diffuser, then combustion and expansion in the engine accelerates the exhaust faster than inlet air to produce thrust. The HyFly program demonstrated a dual-combustion ramjet concept for hypersonic cruise flight at Mach 6 with a liquid hydrocarbon fuel. While ramjets have low drag and can operate at high pressures and temperatures, they also have limitations such as altitude restrictions and lower efficiency compared to engines with mechanical compression like turbojets.

1. PRESENTED BY
KVK

2. PRINCIPLE OF RAMJET ENGINE
THE FUNCTION OF A SUPERSONIC AND
SUBSONIC DIFFUSER IS TO CONVERT THE
KINETIC ENERGY OF THE ENTERING AIR INTO A
PRESSURE RISE CALLED RAM PRESSURE.

3. RAMJET BASIC OPERATION
Ramjet has no moving parts
Achieves compression of intake air by forward speed of vehicle
Fuel
injectors

4. RAMJET BASIC OPERATION
Air entering the intake of a supersonic aircraft is slowed by
aerodynamic diffusion created by the inlet and diffuser to low velocities.
Expansion of hot gases after fuel injection and combustion accelerates
exhaust air to a velocity higher than that at inlet and creates positive
thrust

5. HyFly RAMJET CONCEPT
Hypersonic Flight Demonstration Program
Cruise Flight Mach Number ~ 6
Range 600 nm (1111 km)

6. HyFly RAMJET CONCEPT
HyFly program was initiated in 2002 by DARPA (Defense
Advanced Research Projects Agency) and U.S. Navy's ONR
(Office of Naval Research)
 to develop and test a demonstrator for a hypersonic Mach 6+
ramjet-powered cruise missile
Prime contractor for HyFly missile is Boeing, Aero jet builds
sustainer engine
Air-launched from F-15E and accelerated to ramjet ignition speed
by solid-propellant rocket booster

7. •Engine runs on conventional liquid hydrocarbon fuel (JP-10)
•Much easier to handle than cryogenic fuels (LH2) used on other hypersonic
scramjet vehicles
• Sustainer engine of HyFly is a dual-combustion ramjet (DCR) (very complex)
•Two different air inlet systems
•Operate as a "conventional" ramjet with subsonic combustion
•Operate at hypersonic speeds as a scramjet
•First scramjet engine (hybrid or otherwise) to demonstrate operability
with LH2 fuel

8. Hercules MK 70 rocket booster

11. SUMMARY
 Ramjet develops no static thrust
 Relies on ‘ram’ compression of air
 Requires high speed flight
 Performance depends on increase in stagnation temperature across burner
(combustor)
 Efficiencies (thermal, propulsive, and overall) increase with increasing flight
Mach number
 Next step: We desire an engine that develops static thrust
 Put in a device to mechanically compress air (compressor)
 Put in a device to power compressor (turbine)
 Solution: Turbojet engine

12. ADVANTAGES
LOW FRONTAL AREA.
CO-EFFICIENT DRAG IS LOW.
HIGH PRESSURE AND TEMPERATURE CAN BE
EMPLOYED.
LOAD CAPACITY IS VERY HIGH.

13. DISADVANTAGES
THERE WE HAVING ALTITUDE LIMITATION.
LOW THERMAL EFFICIENCY.
HIGH TSFC.
EROSION OCCURS AT THE NOZZLE DUE HIGH
TEMPERATURE OF GAS COMING OUT FROM THE
NOZZLE.