PAG 12 AZ

PAG 12: The Ramjet

Presented to you by Azuolas M.

X-15 rocket-powered airplane with a ramjet

1. Air flows into the inlet at supersonic speed, compressed to subsonic speed as higher pressure= lower air velocity. Temperature and pressure increased 2. Liquid hydrogen fuel is injected into the combustion chamber, then ignited to reaccelerate the exhaust to supersonic speed. The flame holder maintains continual combustion by preventing the flame from being blown out 3. Exhaust gas is further accelerated by the convergent-divergent nozzle, as a constant mass flow rate means the velocity of the gas increases as cross-sectional area increases

How does a ramjet work?

The engine consists of an air intake, a combustor and an exhaust nozzle, and no moving parts (in contrary to the turbojet, which contains a moving turbine and compressor)

Gas is accelerated by the ramjet, causing thrust due to Newton's third law Requires assisted take-off as no air is 'rammed' into it when stationary

Ramjet engines operate most efficiently at Mach 3 (3x the speed of sound) and up to Mach 6 (4,600 mph), due to the shockwave-induced pressure loss which happens when slowing the intake air to subsonic speed

BrahMos ramjet supersonic cruise missile

Its propulsion has two stages: solid fuel rocket booster and liquid fuel ramjet Rocket booster launches the missile from rest until it is moving fast enough for the ramjet to be used Capable of carrying a nuclear warhead or conventional semi-armour-piercing missile as well being launched from submarine, ships, aircraft or land Flies at an altitude of only 3 or 4 metres, at a max speed of approx. Mach 3 Hypersonic BrahMos-II under development, will be capable of reaching Mach 8 and will have a range of 1000km Really fast.

Ramjet vs Scramjet

Scramjet

The scramjet has a much smaller combustion chamber and nozzle geometry, as it is adapted for travel at much higher velocity (hypersonic: Mach 5 and above) than the ramjet Both the ramjet and scramjet rely on high vehicle speed to compress the incoming air forcefully before combustion occurs A ramjet decelerates the air to subsonic speed before combustion using shock cones which create extremely high pressure and so low velocity, a scramjet doesn't have a shock cone and slows the airflow using shockwaves produced by its ignition source in place of a shock cone, allowing the scramjet to travel at much higher velocities, only then limited by drag

Ramjet

Limitations, advantages and disadvantages

Hiller Hornet (below) with ramjet engines mounted on the rotor blade tips. The Hornet suffered from high fuel consumption and poor range as the tip speeds were subsonic, and so the ramjets were very inefficient

• Though the ramjet has no moving parts and a simple design, it requires an initial velocity to operate, and cannot take off by itself, thus relies on boosters or other jets to reach a suitable velocity

• Notably lighter than a turbojet and can operate at higher speeds, and has a high thrust to weight ratio
• More efficient over long distances than rockets
• FAST

Video!!!!

Enjoy. That's an order.

https://www.youtube.com/shorts/MpCyFtTuJwc

Sauces

https://www.nasa.gov/audience/forstudents/9-12/features/F_Ramjet_9-12.htmlAuthor: Brian Dunbar Title: Ramjet propulsion Date accessed: September 11, 2022 Date written: April 10, 2009 https://www.grc.nasa.gov/www/k-12/rocket/isentrop.html Author: Tom Benson Title: Isentropic flow Date accessed: September 11, 2022 Date written: May 13 2021 https://en.wikipedia.org/wiki/BrahMos Author: Unknown Title: BrahMos Date accessed: September 11, 2022 Date written: 23 August 2022

Thanks!