Calculate Flame Height: Material and Output Hole Size

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Discussion Overview

The discussion revolves around calculating the height of a flame produced by burning a material, specifically focusing on factors such as the type of material, the area of the flame output hole, and the internal pressure of the lighter. The conversation touches on theoretical aspects and practical implications related to flame behavior.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant suggests that flame height could be calculated based on the material being burned and the area of the flame output hole.
  • Another participant proposes that internal pressure in the lighter affects flame height, noting that the flame shortens as the lighter empties due to changes in pressure and exit velocity of the butane.
  • It is mentioned that the air/fuel ratio is significant, with a reference to how different oxygen levels affect flame characteristics, particularly in an acetylene torch.
  • A participant humorously notes the lack of access to acetylene torches for experimentation but acknowledges their effectiveness in demonstrating flame behavior.
  • Another participant references Bunsen burners as a more accessible means to observe similar effects by adjusting air intake.

Areas of Agreement / Disagreement

Participants express various viewpoints on the factors influencing flame height, indicating that there is no consensus on a singular method or formula for calculation. Multiple competing views remain regarding the significance of different variables such as pressure, fuel type, and air intake.

Contextual Notes

Limitations include the dependence on specific definitions of terms like "flame height" and the unresolved mathematical relationships between the discussed variables. The discussion does not reach a definitive conclusion on how to calculate flame height.

Who May Find This Useful

This discussion may be of interest to individuals exploring combustion processes, those studying fluid dynamics in relation to gases, or anyone curious about practical applications of flame behavior in everyday items like lighters and Bunsen burners.

dyiu9632
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Just curious: Is there a way to calculate flame height given the material being burnt and the area of flame output hole (for example a lighter with adjustable flame height)?
 
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I would expect it to depend on the internal pressure in the case of the lighter. This would explain why the flame of a lighter gets shorter as it empties. The velocity at which the butane escapes from the lighter will depend on the pressure of the butane canister and the size of the hole it is escaping from, once you have the exit velocity you'd probably need some number representing how long it takes the butane molecule to burn, on average, then you can just do d=v*t to get an idea of how tall the flame will be.
 
The nature of the fuel itself, and the air/fuel ratio should be of significance as well. I guess that the fuel part is covered by knowing how long a molecule takes to burn, as dice mentioned. As for the air... consider the difference in effect of an acetylene torch at constant pressure with differing amounts of oxygen fed in.
 
Danger said:
As for the air... consider the difference in effect of an acetylene torch at constant pressure with differing amounts of oxygen fed in.

Um... not all of us have acetylene torches to play around with. Not that I'd turn one down, mind you :biggrin:
 
If they still make Bunsen burners the way they did when I was in school, you can get the same demonstration by adjusting the air intake on the bottom.
 

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