×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

thermal expansion & compression of metals due to temperature and force

thermal expansion & compression of metals due to temperature and force

thermal expansion & compression of metals due to temperature and force

(OP)
This is purely a theoretical topic right now...

Trying to find a metal or combination of metals of piping that allow for a certain amount of thermal expansion, while still maintaining their visible structure. Or really, more along the lines of thermal "compression" so to speak, even though that isnt the goal here.

The easiest way I can find to dictate entropy in an exhaust system is (purely theoretical) to have an exhaust manifold that can slightly change inner piping diameter. Picture exhaust gasses moving out of a cylinder head at 1000 mph or more, the flow requirements of the manifold will differ than those required at say half of that speed (of course at a lower load). if the manifold pipings' inner diameter was allowed to ever-so-slightly expand under pressure from increased CFM from the exhaust ports, that would be ideal, theoretically making it easier for the exhaust gasses to flow through the manifold without developing turbulence while stabilizing CFM in the manifold. The only thing is, is this metal compound that would be used, it would have to be coupled with an outer skin of a metal with a lower thermal coiffecent of expansion, to allow the manifold to maintain its shape.

When speaking of the "expansion" of the inner metal, this is really a compression based on force, the force of the increased CFM of the exhaust hitting it at higher speeds. The only thing is that this inner material would have no place to expand to, being it cannot expand inward, (hopefully) due to the forces of the exhaust gasses against it, and it cannot expand outward, due to the outer skin of a metal that has a lower coiffecent of thermal expansion. So the inner material would have to compress (between the exhaust gasses and the outer metal) once its activation energy is met with temperature.

Anyone follow this? Anyone have ideas of materials that could be used in this case? Keep in mind that both materials cannot have their structural integrity challenged to the point of fatigue or worse.

RE: thermal expansion & compression of metals due to temperature and force

Why does the inner material need to be resting against the outer material? Why can't there be a void, or even a vaccuum between the two materials in order to allow the inner material to expand?

RE: thermal expansion & compression of metals due to temperature and force

from some work I've done studying exaust systems the gauge pressure is rarely over 12"H2O, approx .433 PSI. This is not that much pressure. Flow upwards of 800lbs/hr is usual. Temps to 1000C.

(I think that at 12" press 800lbs/hr converts to around 500CFM)

Wow I'm not sure wht material you might use.

Nick
I love materials science!

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources