High Performance Sealing Options (Turbomachinery)

[minger]

Let's say you have a turbojet shaft that needs sealed. Temperatures and pressures are very high (very). Now let's assume that you don't know squat about seals. Aside from brush and labby seals, what other sealing options exist that can operate at extremely high pressures/temperatures (and possibly surface velocities).

[FredGarvin]

The surface velocities are the killer. You really don't have any other choices than labby's or carbon seals. Either a radial or face carbon seal is probably your best bet. Even then, depending on the seal delta P you could still be in trouble.

[minger]

bleh. We're predicting too high leakage rates with the labbys, and I think we're out of the temperature range for carbon face seals. We might find ourselves running a lot of labbys inline...might not have the space for it though.

It's what I figured, but thanks for the info nonetheless.

[Q_Goest]

Hi Minger,
Can you get the seal out of the hot area? Perhaps by moving it down the shaft or extending the shaft?

[FredGarvin]

bleh. We're predicting too high leakage rates with the labbys, and I think we're out of the temperature range for carbon face seals. We might find ourselves running a lot of labbys inline...might not have the space for it though.

It's what I figured, but thanks for the info nonetheless.
There are games to be played with cooling schemes. I am assuming this is in/around an HP turbine?

[minger]

There are games to be played with cooling schemes. I am assuming this is in/around an HP turbine?

Yea, it's a seal for the combustor. Due to the scope of the program (which I won't get into), the shaft has an odd shape, forcing high surface velocities.

We have another guy looking at options, but it seems that we're running out; I figured I'd take a look around. It's kind of funny though, google for high temp seals, and most suppliers' defintion of high temp is like kitchen oven temp...not so much HP spool temps.