Fact i heard about rocket engines, not sure if true.

[Epic DaVinci]

Hi Guys,

I know i could Google this if i want, but whats the point of a discussion forum if we were all just to Google anything?

Anyway, i remember a fact i got told once about the nozzles on large rocket engines. Apparently they will melt in normal use due to the high temperatures, to overcome this, liquid oxygen is pumped around the cone in a concentric spiral to cool the material down, in doing so, the heat helps get the liquid oxygen to a temp that is better for combustion.

Is this true?

As an Aircraft Inspector, i am familiar with the cooling science used in Jet Engines, where the high pressure turbine blades operate at a temp higher than their melting point and are cooled down below this actively.

Peace

EDV

[GJames]

Completely true, it's called regenerative cooling.

[Epic DaVinci]

So, does oxygen like higher temperatures when used in a combustion chamber?

[MBobrik]

isn't that hydrogen that is used for cooling ? higher capacity, lower temperature, and not as aggressive to metals as hot pressurized oxygen.

[GJames]

So, does oxygen like higher temperatures when used in a combustion chamber?

The engine can produce more power if the propellant is as hot as possible when it goes into the combustion chamber as it is at a higher pressure and will exit the rocket at a higher speed, producing more thrust. Obviously there is a limit to how high the temperature or pressure can be in an engine so they normally operate at a few thousand degree's 'C.

[Kialar]

isn't that hydrogen that is used for cooling ? higher capacity, lower temperature, and not as aggressive to metals as hot pressurized oxygen.

If I remember right, then Hydrogen heats up on expansion or evaporation (think, it's called Joule-Thomson-Effect), what means it would be not useful for cooling aspects.

[Rune]

If I remember right, then Hydrogen heats up on expansion or evaporation (think, it's called Joule-Thomson-Effect), what means it would be not useful for cooling aspects.

Oh, but there are fancy tricks to go around that. And hydrogen has an awesome capacity to take away heat. That is why, at least on american engines like the J-2, it is used as coolant fluid for the nozzle and chamber. I don't recall what the russians do right now exactly, but they have metallurgy capable of handling oxygen-rich staged combustion, so I'd say they'd use oxygen 'cause it's netter coolant than RP-1. But that's because their pipes don't mind having liquid oxygen going through them at 500º.

Rune. Which is like,

[Kryten]

Russian engines still use fuel as the coolant, oxygen would eat straight through even their piping at those kind of temperatures. You frequently have 'film cooling' in addition to regenerative, where fuel is injected between the chamber wall and the actual area of combustion; this also leaves layers of protective soot on the wall. Film cooling has actually been shown to work with oxygen; a semi-amateur rocket group (think it was AA) made an engine, did some test firings which worked properly, then discovered it'd been plumbed to the test stand incorrectly...

Edited May 21, 2013 by Kryten

[Rune]

Russian engines still use fuel as the coolant, oxygen would eat straight even their piping at those kind of temperatures. You frequently have 'film cooling' in addition to regenerative, where fuel is injected between the chamber wall and the actual area of combustion; this also leaves layers of protective soot on the wall. Film cooling has actually been shown to work with oxygen; a semi-amateur rocket group (think it was AA) made an engine, did some test firings which worked properly, then discovered it'd been plumbed to the test stand incorrectly...

The more you know... so only the turbopumps are made of their "adamantium"? Makes sense. Thanks!

[OdinYggd]

Typically the fuel is used instead of the oxygen- hot oxygen becomes too reactive and will literally eat hardware.

But yes, most engines using LH2 or RP1 will pump fuel through passages in the nozzle throat and bell to keep the nozzle within its safe temperature range. The hot fuel atomizes easier with less risk of icing up an injector, making for better performance.

[Hyomoto]

I wish I could answer your question, but I'm stuck on how it can be a fact if you do not know if it is true? It's like the phrase, 'here's a true fact'. That's what a fact is, something that has been proven to be true. You might say, "I'm unsure if this is a fact or not." or, "Here's something I heard, is it true?", or if you read it, "Here's something I read, is it true?". I don't understand what the barrier to using appropriate words is. It's not grammar that bothers me, it's the lackadaisical use of language. People often say, "You know what I meant.", to which I reply, "I know what you said, is that what you meant?"

Words mean things, please question what it is.

[ROFLCopter64bit]

You can replicate the effects of this with Propane.

(Come on Nova, quote this post and reply with a wacky reply!)

[Epic DaVinci]

I wish I could answer your question, but I'm stuck on how it can be a fact if you do not know if it is true? It's like the phrase, 'here's a true fact'. That's what a fact is, something that has been proven to be true. You might say, "I'm unsure if this is a fact or not." or, "Here's something I heard, is it true?", or if you read it, "Here's something I read, is it true?". I don't understand what the barrier to using appropriate words is. It's not grammar that bothers me, it's the lackadaisical use of language. People often say, "You know what I meant.", to which I reply, "I know what you said, is that what you meant?"

Words mean things, please question what it is.

Dude, seriously? You're giving me a lecture on correct use of Word structure on a forum about a Space Rocket game?

My Apologies if my understanding of the English language is not as advanced and perfect as yours.