My Project
A general introduction:
Imagine a plane that can fly eight times the speed of sound…New York to New Delhi in 4 hours!!
It is possible, in the near future of course, with hypersonic propulsion
systems like the scramjet. In the conventional aircraft engines like a
turbojet or a turbofan, air is compressed and heated in a burner and then
made to flow through a turbine to extract just enough work to run the
compressor. The hot gases are now expanded through a nozzle to increase the
velocity and thus thrust is produced. Simple enough. The problem is that
really high speeds, the operating temperatures increase to a level that no
man made material can withstand let alone made to rotate at 30,000 rpm. So
what’s the way out???
One easy way out is to have an engine that has no rotating parts. That is, take the
turbine out of the way…and use a ramjet Now, what’s a ramjet?? Well…it is
somewhat like a flying pipe. When this ‘pipe’ is flying at velocities above
the speed of sound, the air gets rammed into the duct of the ramjet increasing
its pressure. Then the air is heated and expanded through a nozzle to create
thrust. To heat the air fuel has to be added, so basically you would have to
slow the air down otherwise the heat release would be too little too late to
produce any thrust. Scramjets on the other hand use fuels like Hydrogen that
can burn really fast at high velocities. Perfect so far…wait a sec didn’t we
miss something? To get a ramjet or a scramjet running they have to fly at
speeds above the speed of sound. Chicken and the egg problem? Not
quite…actually rockets boost them to the required velocity. But unless you are
an aspiring astronaut you wouldn’t like to be shot into the air with a rocket.
Besides, they are heavy ‘cause they have to carry both fuel and oxidant on
board and then finally you want your plane to slow down and land don’t you?
How do you do that with a propulsion system that does work below the speed of
sound?