A ramjet is a jet engine with no compressor and no turbine. It uses the speed of the vehicle itself to squeeze the air, then burns fuel and throws the hot gas out the back. Follow the air from the intake to the exhaust.
A ramjet is a jet engine that has no moving parts in the airflow. It relies on the speed of the vehicle to push air into a shaped duct, where the air is slowed and compressed, then mixed with fuel and burned. The hot gas leaves through a nozzle as a fast jet.
From the outside a ramjet is just a tube. Everything that matters â how the air is squeezed, where the fuel goes in, and how the flame is kept alive in a fast stream â happens inside the duct, so a cutaway is the clearest way to see it.
The engine has no compressor, so forward speed itself does the work. Air rams into a converging inlet and diffuser that slows it down, and slowing the air raises its pressure so it can be burned.
Injectors spray fuel into the fast-moving air stream as it enters the combustor. The fuel is broken into a fine mist so it mixes and burns quickly rather than pooling.
Combustion air moves very fast and can blow a flame out. The V-shaped flame holder creates a pocket of slower, recirculating air behind it, giving the flame a place to stay lit.
Fuel and air burn, adding heat. The gas leaving the combustor is hotter and at a higher pressure than the air that entered, which is what gives the ramjet its push.
The hot gas passes a narrow throat and then widens through the exhaust nozzle, accelerating to high speed. Throwing that fast-moving mass backwards is what drives the vehicle forwards.
It uses forward speed instead of a compressor. The air rams into a converging duct that slows and compresses it, so there is no need for a rotating compressor or turbine in the flow.
No. With no moving parts it cannot pull air in by itself, so it only produces thrust once it is already moving fast enough for ram pressure to work.
Combustion air moves very fast, which can blow a flame out. The flame holder is a V-shaped gutter that traps a small pocket of slower, recirculating air where the flame can stay lit.
It converges to a narrow throat and then widens. That shape lets the hot gas expand and accelerate to high speed, and faster exhaust means more thrust.
Where something already provides high speed and a simple, light engine is useful. It is studied for high-speed commercial transport concepts and used in some high-speed test vehicles.