I'm aware that the difference in density with respect to height is low, but I'm in need of the values for a project: in which I explain that the continuity equation of fluid dynamics will work well for gases as an approximation since the density difference is not high for different heights of a flame.

p.s: the project is a video explaining the tapering of flame. I also would like to know if showing the values of temperature incase I can't get the values for density would be acceptable.

up vote 1 down vote accepted

The approximate values of density for a flame with respect to heights

I'm aware that the difference in density with respect to height is low, but I'm in need of the values for a project: in which I explain that the continuity equation of fluid dynamics will work well for gases as an approximation since the density difference is not high for different heights of a flame.

Check out: "Jet flame heights, lift-off distances, and mean flame surface density for extensive ranges of fuels and flow rates", (DOI link: https://doi.org/10.1016/J.COMBUSTFLAME.2015.09.009) by Derek Bradley, Philip H. Gaskell, Xiaojun Gu, and Adriana Palacios for formulas to make these calculations:

"The correlations are based on a vast experimental data base, covering 880 flame heights. They encompass pool fires and flares, as well as choked and unchoked jet flames of CH$_4$, C$_2$H$_2$, C$_2$H$_4$, C$_3$H$_8$, C$_4$H$_{10}$ and H$_2$, over a wide range of conditions. Supply pressures range from 0.06 to 90 MPa, discharge diameters from 4·10$^{-4}$ to 1.32 m, and flame heights from 0.08 to 110 m.".

See also: "The size of flames from natural fires", (11 October 2007) by P.H.Thomas. Origonal paper: Source: Fire Safety Science Digital Archive. "This paper discusses one of the least studied features of natural fires - the length of the turbulent flames rising from the burning fuel.".

An answer about backpressure: Why does exit pressure matches back pressure in a converging diverging nozzle?

PS: The project is a video explaining the tapering of flame.

Here's a great video from NASA: "NASA’s new High Dynamic Range Camera Records Rocket Test", not much tapering in that view but it's shot in HDR and shows the turbulence of the burning.

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.