The Indian Space Research Organisation (ISRO) has successfully tested the Hot Test of Scramjet Engine at ISRO's Propulsion Research Complex at Mahendragiri in Tirunelveli district of Tamil Nadu.
Scramjet Engine:
Scramjets (supersonic-combustion ramjets) are ramjet engines in which the airflow through the whole
engine remains supersonic.
Like ramjet, scramjets have no moving parts inside the engines and inherit all the fundamental requirements
like primary propulsion system to accelerate them to supersonic speeds.
It allows supersonic combustion by breathing oxygen from the atmosphere during flight.
It then allows the oxygen to mix with hydrogen already stored in the vehicle to trigger combustion, and
produce the desired thrust to lift the satellite to its designated orbit.
If the engine in the launch vehicle can breathe oxygen from the atmosphere, that will reduce nearly 70% of the
propellant that has to be carried in the vehicle.
While scramjets are conceptually simple in design and construction, actual implementation is limited by
extreme engineering challenges.
Scramjet technology is challenging because only limited testing can be performed in ground facilities. Long
duration, full-scale testing requires flight test speeds above Mach 8.
Ramjet Engine:
It is an air breathing jet engine, which uses the engine’s forward motion to compress incoming air, without a
rotary compressor present in jet engines.
By design, ramjets cannot produce thrust at zero velocity, initially when they are still. Therefore, the
aircrafts require a propulsion system to initiate the movement for compression in the ramjet to undertake.
Ramjets operate by subsonic combustion of fuel in a stream of air compressed by the forward speed of the
aircraft itself, as opposed to conventional turbojet engines, in which the compressor section (the fan blades)
compresses the air.
In comparison to turbojets, ramjets have no moving parts.