How Rocket Engines cooling system work ?

Our heavenly Internal Combustion Engines used in cars & bikes can be cooled by air & water or coolant circulating around it. But what about rocket engines ? How rocket engines cooling system works ?

The engines of rocket heat up upto 6000°C. At this temperature the metals would become so hot that they would melt & even some of them would vaporise. Circulating water or a normal coolant around it wasn’t going to help. Finally,  rocket scientists have to take the engine cooling to a whole new level.
What if I tell you that, the rocket’s fuel itself is used to keep the engines cool. I know this sounds totally CRAZY but yea that’s what really happens ! & also did I mention that these engines are reused by NASA  !

So how rocket engines cooling system work ?

The huge orange thing(in the above image) you see is the fuel tank of rocket – carrying thousands of gallons of super-cooled liquid Hydrogen – the rocket’s propellant. The super-cooled propellant has a mind-blowing temperature of -253°C, which is perfect for cooling the engine.

NASA's rocket thrusters

Distribution of pipes or channels OUTSIDE the combustion chamber (fuel flows right to left through pipes).

thin tubes ehich carr LH2

Smaller tubes which inject LH2 INSIDE the combustion chamber for combustion ( now left to right according to above pic )

The propellant- Liquid hydrogen is passed through tubes or channels around the combustion chamber of the rocket. Now the heated propellant is injected directly through smaller tubes back into the main combustion chamber for combustion there. The American style of lining the engine with copper tubes is called the “spaghetti construction”. Fuel flowing through the tubes or corrugations absorb the heat very efficiently. The heat is absorbed so efficiently that the temperature drops down from 6000°C to just 54°C.

This is also called Regenerative cooling.



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