Ever
thought of travelling at a speed of more than 7000 km/hr . Flying at supersonic
and hypersonic speed is need of the present world and the dream that every
aeronautical engineers want to be true. But now, hypersonic and supersonic
travel is not a dream but a reality. With the use of Ramjet and Scramjet engine
hypersonic travel are possible. Ramjet and Scramjet works on a same principle
with similar design, differing only on the method of combustion of air. Ramjet
slow the air to subsonic flow before combusting
while Scramjet combust it at supersonic flow.
Also
referred to as flying stovepipe, Ramjet engine can operate upto speed of MACH 6
(7350 km/hr). Ramjet engine is different from the turbojet engine as it
compresses air without using a rotary compressor. Ramjet are used in missiles,
artillery shells, supersonic aircraft that require a small and simple mechanism
to acquire high speed.
Ramjet
has a disadvantage that it cannot work on a low velocity means that it cannot
move an aircraft from standstill. Thus it require a very high supersonic
velocity to produce thrust as they use it own speed to compress air. Ramjet at
least need a velocity of around MACH 3 to propel the aircraft upto MACH 6.
Ramjet
works on a Brayton cycle. The main design that guides the working of Ramjet is
its inlet. Ramjet does not contain any rotating parts and thus it is easier to
built and maintain. The conical design at a inlet compresses air using high
pressure in front of it and force it through the tube to combusting chamber,
where it is heated with fuel and ejected through nozzle to accelerate it to
supersonic speed. The nozzle acts as a critical part of ramjet design, since it
accelerates exhaust flow to produce thrust,
Ramjet
have find its use successfully in Russian Indian Brahmos missile and Indian
Akash missile. It has also been used as tip jet on helicopter rotors. The world
fastest plane Lockheed SR-71 engine acts as ramjet when flying at high speed.
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