SSME bending

Watch the flow separation during ignition bend the 1071 braze welded steel tubes on that nozzle. The nozzle was over expanded to make it more efficient in a vacuum but temperamental to start up.

Category:

Science & Technology

Tags:

• SSME
• bending

[UAL1200]

@MichaelCox

The ribs on the nozzles do provide some structural benefit, but they also serve another purpose. The hot exhaust would easily melt the nozzle during flight, so to solve this problem the liquid propellant (which is at ridiculously low temperatures) is piped through those ribs to cool the nozzles. The ribs coil around the nozzle top to bottom for cooling then shoot back up into the chamber for combustion.

[khalilovH]

resonance, some times it can be destructive .. engineers takes it seriously into account 

[marmaladekamikaze]

@dcb1138

No I'm talking about the vertical white fluid coming out of the edge of the engine bell, that is directed down into the flame trench. The Horizontal sparks you're talking about are pieces of Zirconium metal from the NASA standard igniter IIRC.

[marmaladekamikaze]

@dcb1138

that sounds plausible! thanks

[dcb1138]

@marmaladekamikaze - Actually I rechecked what your talking about. Do you mean the white horizontal "sparks" being shot across the engine bell outlet ? If so...its sparks to burn off any stray Hydrogen before ignition.

[dcb1138]

@marmaladekamikaze - I believe its the initial H2-O2 injection before its ignited. The turbo pumps have to get up to full speed before ignition.

[MSLTUL]

Man, this is cool stuff. I'm glad I was able to see this before I die - and that may not be too far down the road.

[marmaladekamikaze]

@UAL1200

you seem like a pretty knowledgeable guy, I've had this question bugging me about the SSME for a while. Prior to engine igntion with the pyro igniter, ~ T -5 coming from the edge of the bell nozzle a white vapor jet appears to shoot down into the flame trench, I've always wondered what this was for? I've thought maybe is it LH2 being dumped, but if it is why waste it? if you know what it is, and what its for, I'd really appreciate an explanation, it bugs the heck out of me!

[krebsderek]

Pretty much what grogadile said. All liquid fuel rocket motors experience combustion instability particularly on ignition. The motor is designed to self damp after oscillations such as the one shown occur. Keep in mind that this was taken with a high speed camera, the oscillation likely happened within 1/10 of a second and what you are seeing is likely the harmonics of a 4k-24kHz oscillation. The issue is more problematic on larger rockets which is why the Russians use small clusters.