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How are rocket engine pumps powered ?



 
 
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  #1  
Old October 8th 07, 08:33 AM posted to sci.space.history
Andre Majorel
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Default How are rocket engine pumps powered ?

Since posting to sci.space.tech seems to be a no-op...

Been wondering... Rocket engine turbopumps must need quite a bit
of power. Where does it come from ?

--
André Majorel URL:http://www.teaser.fr/~amajorel/
(Counterfeit: )
There is always someone somewhere who needs a good laugh.
  #2  
Old October 8th 07, 09:00 AM posted to sci.space.history
Dave Michelson
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Default How are rocket engine pumps powered ?

Andre Majorel wrote:
Since posting to sci.space.tech seems to be a no-op...

Been wondering... Rocket engine turbopumps must need quite a bit of
power. Where does it come from ?


The usual approach is to burn some of the fuel and oxidizer in a
preburner or gas generator. This produces the hot gas that drives the
turbines.

Sometimes the preburner exhaust is dumped overboard. In other cases, it
is pumped into the combustion chamber.

The entire scheme is referred to as an engine cycle. The SSME's engine
cycle is particularly complicated :-\

--
Dave Michelson

  #3  
Old October 8th 07, 10:19 AM posted to sci.space.history
Pat Flannery
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Posts: 18,465
Default How are rocket engine pumps powered ?



Andre Majorel wrote:
Since posting to sci.space.tech seems to be a no-op...

Been wondering... Rocket engine turbopumps must need quite a bit
of power. Where does it come from ?


Depends on the engine.
In the case of the engine on the the German A4 (V-2) engine it came from
decomposing hydrogen peroxide into high temperature and pressure steam
that drove a turbine that moved the Lox and alcohol into the combustion
chamber via two separate turbopumps that were attached to its drive shaft.
Amazingly enough, that's the way all of the 2,000+ Russian R-7 ICBM
derivatives that shot everything from Sputnik 1 to the latest Progress
and Soyuz's up to the ISS also works.
This was followed by feeding the two main propellants into a separate
turbine where they burned and had their exhaust ejected through a tube
mounted on the bottom of the rocket. Thats where the big blast of sooty
fire came from under a Atlas ICBM:
http://www.fas.org/nuke/guide/usa/icbm/atlas-d-icbm.jpg (to the right
of the main exhaust)
You ran that turbopump with too much kerosene compared to the Lox so it
wouldn't overheat.
After that idea they were fed back inside the nozzle of the rocket
engine to cool its walls by sheathing it in a veil of fairly
low-temperature flame, which is what the big ring around half way down
the nozzles of the Saturn V's F-1 engines are about, and why when you
see the liftoff of a Saturn V showing its base close-up what's coming
out of its engine nozzles looks black for a few feet behind it:
http://www.sierraengineering.com/Plume/f1enginefire.jpg
Again, it's kerosene rich so it doesn't overheat the turbopump.
Next step up was to run the turbine rich in either fuel or oxidizer, and
send the exhaust straight into the combustion chamber; this worked great
in two ways; first the combustion of the two propellants with one being
way too abundant kept the temperature in the turbopump propellant feed
turbine low, so it didn't need exotic high temperature alloys to build
it; secondly, the exhaust from the turbopump feed turbine came into the
combustion chamber at high heat, allowing better combustion when it
arrived and reacted with the other propellant.
You can see where this is heading, can't you?
Let's put _two_ turbopumps on the engine, run one top heavy with the
fuel, and the other top heavy with the oxidizer. Temperatures in each of
the feed turbines are kept low due to the unbalanced propellant mixture,
yet what heads into the combustion chamber arrives as very hot gas and
basically reacts in a microsecond after finding another hot atom that's
ready for it.
Welcome to the SSME...Space Shuttle Main Engine:
http://webpages.charter.net/tsiolkov...otos/ssme3.gif
Turbopump exhaust goes in one side with too much hydrogen to burn, and
in the other side with too much oxygen to burn, and hot hydrogen gas
runs into hot oxygen gas in the combustion chamber and turns into
superheated water steam because...it's now H2O.

Now that's slick. :-)

Pat

  #4  
Old October 8th 07, 09:12 PM posted to sci.space.history
Damon Hill[_4_]
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Posts: 566
Default How are rocket engine pumps powered ?

The SSME turbopumps both run hydrogen-rich; the hot gas
is ducted into the main combustion chamber into which
the remaining oxygen is injected. The exhaust is still
somewhat hydrogen-rich, to maximize specific impulse.

Oxygen-rich propulsion systems are the exclusive province
of the Russians, both kero-LOX and hypergolic (Proton).
That's quite a trick, keeping the hot oxygen-rich gas
from eating the engine; done partly with compatible materials
and coatings and by limiting peak temperature in the
turbopump section.

Then there's the expander cycle, which doesn't use preburners
or any type of hot gas turbopump at all. Just warmed hydrogen
that was used to cool the combustion chamber and exhaust
nozzle. Now that's elegant.

--Damon

  #5  
Old October 9th 07, 06:23 AM posted to sci.space.history
Pat Flannery
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Posts: 18,465
Default How are rocket engine pumps powered ?



Damon Hill wrote:
The SSME turbopumps both run hydrogen-rich; the hot gas
is ducted into the main combustion chamber into which
the remaining oxygen is injected. The exhaust is still
somewhat hydrogen-rich, to maximize specific impulse.


My bad. :-[

Pat
  #6  
Old October 10th 07, 11:53 PM posted to sci.space.history
Andre Majorel
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Posts: 2
Default How are rocket engine pumps powered ?

On 2007-10-08, Dave Michelson wrote:
Andre Majorel wrote:

Been wondering... Rocket engine turbopumps must need quite a bit of
power. Where does it come from ?


The usual approach is to burn some of the fuel and oxidizer in a
preburner or gas generator. This produces the hot gas that drives the
turbines.


That's elegant. No batteries, no dynamos, no ICE.

Thanks for the explanations, folks.

--
André Majorel URL:http://www.teaser.fr/~amajorel/
(Counterfeit: )
There is always someone somewhere who needs a good laugh.
  #7  
Old October 11th 07, 03:16 AM posted to sci.space.history
Pat Flannery
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Posts: 18,465
Default How are rocket engine pumps powered ?



Andre Majorel wrote:
That's elegant. No batteries, no dynamos, no ICE.

Thanks for the explanations, folks.


If you want to see a wild rocket engine design, check out the one from
Sanger's WW II Antipodal Bomber design from WWII
This uses steam generated by water flowing around the combustion chamber
to drive the turbopump, then cools the steam back into water by running
it through a heat exchanger surrounded by Lox - this heats the Lox and
improves the engine's overall efficiency; there are drawings of it on
pages 9 and 10 of the PDF he http://www.astronautix.com/data/saenger.pdf
As well as a description of how it works afterwards.
Although heavy, it's an intriguing concept.

Pat

  #8  
Old October 11th 07, 10:16 PM posted to sci.space.history
Derek Lyons
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Posts: 2,999
Default How are rocket engine pumps powered ?

Pat Flannery wrote:

If you want to see a wild rocket engine design, check out the one from
Sanger's WW II Antipodal Bomber design from WWII
This uses steam generated by water flowing around the combustion chamber
to drive the turbopump, then cools the steam back into water by running
it through a heat exchanger surrounded by Lox - this heats the Lox and
improves the engine's overall efficiency; there are drawings of it on
pages 9 and 10 of the PDF he http://www.astronautix.com/data/saenger.pdf
As well as a description of how it works afterwards.
Although heavy, it's an intriguing concept.


It would be fun to make work too...

D.
--
Touch-twice life. Eat. Drink. Laugh.

http://derekl1963.livejournal.com/

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL
  #9  
Old October 11th 07, 11:47 PM posted to sci.space.history
Pat Flannery
external usenet poster
 
Posts: 18,465
Default How are rocket engine pumps powered ?



Derek Lyons wrote:
If you want to see a wild rocket engine design, check out the one from
Sanger's WW II Antipodal Bomber design from WWII
This uses steam generated by water flowing around the combustion chamber
to drive the turbopump, then cools the steam back into water by running
it through a heat exchanger surrounded by Lox - this heats the Lox and
improves the engine's overall efficiency; there are drawings of it on
pages 9 and 10 of the PDF he http://www.astronautix.com/data/saenger.pdf
As well as a description of how it works afterwards.
Although heavy, it's an intriguing concept.


It would be fun to make work too...


Yeah, everything had better work just right or the Lox heat exchangers
blow up from too much Lox vaporization, or the steam coming from the
turbopump turns into ice inside the heat exchanger from over-cooling and
clogs it, at which point the combustion chamber melts. :-)

Pat
  #10  
Old October 12th 07, 01:32 AM posted to sci.space.history
Derek Lyons
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Posts: 2,999
Default How are rocket engine pumps powered ?

Pat Flannery wrote:

Derek Lyons wrote:

This uses steam generated by water flowing around the combustion chamber
to drive the turbopump, then cools the steam back into water by running
it through a heat exchanger surrounded by Lox - this heats the Lox and
improves the engine's overall efficiency; there are drawings of it on
pages 9 and 10 of the PDF he http://www.astronautix.com/data/saenger.pdf
As well as a description of how it works afterwards.
Although heavy, it's an intriguing concept.


It would be fun to make work too...


Yeah, everything had better work just right or the Lox heat exchangers
blow up from too much Lox vaporization, or the steam coming from the
turbopump turns into ice inside the heat exchanger from over-cooling and
clogs it, at which point the combustion chamber melts. :-)


I was thinking more along the lines of the coolant going to steam in
the cooling passages (a Very Bad Thing). Or taking a slug of water
into the turbine (there doesn't seem to be a steam/water
seperator[1]).

Not to mention the startup/shutdown transients in such a system are
going to be... interesting. (On top of the thermal balance issues.)

D.

[1] And making one that will work both on the ground and under
acceleration will be decidely non-trivial.
--
Touch-twice life. Eat. Drink. Laugh.

http://derekl1963.livejournal.com/

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL
 




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