Nk-33 Cooling Flow Question

[CardBoardBoxProcessor]

Hello, The Nk-33 engine uses fuel to cool it's nozzle and I see where it is introduced into the nozzle but I was curious as to if anyone knows the path in which it takes once inside the nozzle jacket. I see it has return lines about the nozzle for said fuel but I cannot figure out the exact path. If anyone has information about this please feel free to add arrows to the image below to depict it please. It would be appreciated

[Zero-G]

Hi, Do you already know this interesting website? http://www.lpre.de/sntk/NK-33/index.htm
It has some interesting diagrams. You can translate the description via Google Translator, if you don't understand Russian. Maybe you can find some answers there.

[CardBoardBoxProcessor]

yeah I read through it but could not determine where it flows inside it. If anyone knows about the merlin 1C it looks to have a similar fuel flow pattern as its plumping looks similar cooling system wise.

here the blue arrow is where it enters the manifold. I don't understand where it goes from there. It would make perfect sense for those regen cooling return lines (the green circles) if it had a double jacket. However the description merely says it has 1 bronze jacket and one outer steel jacket.

[Jim]

I would say none are return. All are inlets.  The return is the jacket and it interfaces with the injector at the top. As the nozzle gets wider, more fluid has to be added.  The fluid goes down the channels in the jacket and back up the channels.  That is how flow is in tubes on Rocketdyne engines.

Also, the lines on the Merlin are not returns but inlets.

[R7]

here the blue arrow is where it enters the manifold. I don't understand where it goes from there. It would make perfect sense for those regen cooling return lines (the green circles) if it had a double jacket. However the description merely says it has 1 bronze jacket and one outer steel jacket.

Despite the risks gotta disagree with Jim and agree with you that the green circled lines are return lines from nozzle lip. Attaching diagram from lpre site to which highlighted the inlet manifold and return lines with same colors as in your picture. Inlet manifold sends fuel both up and down, return manifold near nozzle lip recollects the fuel sent down which is then piped up and reintroduced into coolant channels above throat.

[CardBoardBoxProcessor]

interesting. In each case though It would require a secondary inner jacket. Or at least partially. (Which rd-170 family engines have) we could compare that tubing scheme but it is a tad different. and the addition of its extra plumping completely changes how things work.

[R7]

In each case though It would require a secondary inner jacket.

Why? If pressure drop via both routes from inlet manifold to the upmost manifold above throat are matched then shouldn't return line flow be able to mix into same channels (see attachment). Note that I'm not sure though how the channeling actually is done, just don't see immediate reason why it couldn't be as simple as this. Maybe someone at Orbital could saw an AJ-26 open and take a picture 

[baldusi]

Wasn't the NK-33 made by sandwiching a corrugated metal? At least Wikipedia (for what its worth) says:

The nozzle was constructed from corrugated metal, brazed to an outer and inner lining, giving a simple, light but strong structure.

[CardBoardBoxProcessor]

Yes a link to an L2 thread would be nice

But Yes! Corrugated metal between the outer steel jacket and inner bronze throat would allow for a double path so to say. 

R7s picture has an element from the rd-170 family so that is probably the m most sound.