×
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

Burn pattern opinions

Burn pattern opinions

Burn pattern opinions

(OP)
What causes some areas of the combustion chamber to coat with carbon while other areas remain clean?




RE: Burn pattern opinions

Flame travel, mixture distribution, surface temperature

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Burn pattern opinions

what he said.

RE: Burn pattern opinions

(OP)

Quote (patprimmer):

Flame travel, mixture distribution, surface temperature


So the flame travel stops because conditions are unfavorable for combustion, low temperatures and/or poor air/fuel mixture. Therefore modifications that enhance mixture quality should extend flame travel and accomplish complete burn.

Would the additional heat in the end gas zone promote detonation?

 

RE: Burn pattern opinions

Additional heat could promote detonation.

Also, liquid fuel particles are much heavier than air, and I would expect, tend to flow straight out from the valve whereas the air turns the corner easier, so I would expect richer.

Soot collects on some areas, but burns off others, so it can be no soot on cold surfaces, or less soot on hot surfaces, depending on mixture, power output and running conditions.

There is more to it I am sure, but I do not have time to elaborate my thoughts right now.

 

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Burn pattern opinions

(OP)
Patprimmer,
Thanks, I would love to here more when time permits

RE: Burn pattern opinions

Understand that the incoming air and fuel is more akin to a fluid with air and fuel stratification, rather than a totally homogenous mixture.  What is desired is seldom fully reached.  Placing the fuel injector directly at the intake valve leads to this division, relying on ultrafine spray patterns to obtain a reasonably good air-fuel mixture.  The rest of the mixture enhancement is up to the piston shape, the combustion chamber shape and the heat of the chamber to enhance combustion.

The piston dome is an integral portion of the combustion chamber and the movement of the piston causes a focusing effect of the air-fuel mixture.

Cylinder wall wetting also contributes to hot and cold sections of the combustion chamber, along with carbon deposits and other mechanical factors.

Franz

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: Burn pattern opinions

(OP)
The two examples both show areas wet with fuel, one obviously a better design than the other. My desire is to understand the effects of eliminating the wet areas in the chamber and when doing so will end gas be exposed to higher temperatures eliminating quench areas and leading to elevated end gas detonation.

RE: Burn pattern opinions

I've just been looking at an SAE paper(#950680) on combustion chamber deposits. According to the paper, brown and lighter areas are the coldest (and thinnest deposits), black areas are hot and black "caked" areas (looking like a dry river bed) are the hottest (and thickest deposits) areas in the chamber. The clean areas could be areas that are the coolest, too cool perhaps for deposits to form.

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