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Engine cooling – why rocket engines don’t melt

  • 558 points
  • 6 days ago

  • @wolfram74
  • Created a post
  • • 162 comments

Engine cooling – why rocket engines don’t melt


@soheil 5 days

Replying to @wolfram74 🎙

In fuel-rich engines can't the fuel be harvested after it does its function of cooling the chamber walls at the end of the nozzle. There are cases where fuel is boiling before it's ignited so I don't think the heat will be an issue. If it's not possible to have a pipe that transfers the fuel from the end of the nozzle back to the tip of the engine because of re-transfer of heat can't there be a secondary small engine near the end of the main engine that directly gets its fuel from the excess fuel used to cool the main engine?

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@Animats 6 days

Replying to @wolfram74 🎙

Making rocket engines by metal 3D printing has become popular. A rocket engine bell and combustion chamber has one big rigid part with lots of channels and voids inside. That's the ideal case for 3D printing. Much simpler than building the thing up by machining and welding together many individual parts.

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@ortusdux 6 days

Replying to @wolfram74 🎙

One of my favorite bits from Tim's videos was during a tour of Firefly Aerospace's facility when they talk about engine cooling. They discuss EDM machining small holes into the coolant channels just before the throat, which lets a small amount of cryogenic coolant out to cool the interior. The funny part is that you can purposefully undersize the holes and they will melt larger until they are big enough to adequately cool the engine. You basically pre-season the engine with a test-fire and let it choose how much internal cooling it needs.

https://youtu.be/ac-V8mO0lWo?t=2203

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@WalterBright 6 days

Replying to @wolfram74 🎙

The turbopump, regenerative cooling, and boundary layer cooling by drilling holes, were innovations from the V2.

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@trhway 5 days

Replying to @wolfram74 🎙

a bit related - modern turbofan engines are running extremely hot and to avoid damage/melting to the turbine blades the blades are cooled from inside and with the boundary layer by the cooling air flowing out of the holes in the blade

https://www.researchgate.net/figure/Evolution-of-turbine-ent...

https://www.youtube.com/watch?v=4FqMLyo7fyU

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@soheil 5 days

Replying to @wolfram74 🎙

Serious question: why is it bad to run your rocket engine-rich? If you know you're not going to use the engine and it's nearing its end of life why not get more power out of your fuel/oxidizer by hitting the stoichiometric point? Also, if engine is melting maybe allow it to continue to melt, but at a lower rate and rebuild it later.

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@shmeeed 5 days

Replying to @wolfram74 🎙

Anybody interested in this topic might want to read the NASA Saturn V Owners' Workshop Manual: 1967–1973 (Apollo 4 to Apollo 17 & Skylab) by David W. Woods. It's an incredible collection of information, tables, and drawings relating to the Saturn V's development and operations.

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@jamesmunns 6 days

Replying to @wolfram74 🎙

This is just a really clearly written introduction of a lot of rocket engine concepts.

It was a super good read.

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@mountainwalker 6 days

Replying to @wolfram74 🎙

Tim's videos are always so well done! Even if you're not a rocket enthusiast there's tons to get out of this video.

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@bernulli 6 days

Replying to @wolfram74 🎙

Minor nitpick: fluids are not either liquids or gases, this is particularly true for rocket engines where many of the discussed processes (injection, compression, regenerative coolant flow) actually occur at super- or transcritical conditions.

Also, I don't think you can say the faceplate is heat sink-cooled. Remember that just behind it is the propellant manifold, so it's rather some form of regenerative cooling.

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@jpm_sd 6 days

Replying to @wolfram74 🎙

Ignorant question: are solid-fueled rockets at all interesting, anymore? Do they have any advantages (e.g. simplicity of design) over the fancy throttle-able liquid-fueled engines?

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@opwieurposiu 6 days

Replying to @wolfram74 🎙

This thing I can not comprehend about rocket engines is how the turbopump manages to hold together.

A turbine blade in the SSME about the size of your thumb makes 600 horsepower.

https://www.enginehistory.org/Rockets/SSME/SSME6.pdf

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@Dig1t 6 days

Replying to @wolfram74 🎙

Everyday Astronaut is such an impressive dude, I don't understand why he doesn't just work for SpaceX at this point. He knows more about rocket engineering and can explain it 10x better than most aerospace new grads.

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