High Performance Sealing Options (Turbomachinery)

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Discussion Overview

The discussion revolves around sealing options for a turbojet shaft operating under extremely high temperatures and pressures. Participants explore various sealing technologies suitable for high-performance applications in turbomachinery, particularly in the context of a combustor seal with unique design constraints.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant suggests that aside from brush and labby seals, other sealing options for high temperatures and pressures need to be considered.
  • Another participant argues that carbon seals, either radial or face types, are likely the best options, but notes potential issues with seal delta P.
  • A participant expresses concern about high leakage rates with labby seals and questions the suitability of carbon face seals for the temperature range involved.
  • There is a suggestion to potentially relocate the seal away from the hot area by modifying the shaft design.
  • Participants discuss the possibility of using cooling schemes to manage temperatures around the seal.
  • One participant highlights the challenge of finding suppliers that meet the high-temperature requirements for seals in high-performance applications.
  • A question is raised about the feasibility of routing high-pressure bleed air through a cooler before directing it back to the seal area.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of various sealing options, with no consensus reached on the best approach. Concerns about leakage rates and temperature limits remain unresolved.

Contextual Notes

Participants mention specific challenges related to the unique shape of the shaft and the high surface velocities involved, which may limit the effectiveness of certain sealing technologies. The discussion also reflects a lack of clarity regarding the definitions of high temperature in the context of seal suppliers.

Who May Find This Useful

Engineers and professionals involved in turbomachinery design, particularly those focused on sealing technologies in high-temperature and high-pressure environments.

minger
Science Advisor
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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).
 
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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.
 
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.
 
Hi Minger,
Can you get the seal out of the hot area? Perhaps by moving it down the shaft or extending the shaft?
 
minger said:
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?
 
FredGarvin said:
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' definition of high temp is like kitchen oven temp...not so much HP spool temps.
 
Could you route high pressure bleed air through a cooler then back into the seal area?
 

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