Improved prediction of buoyancy effects on flame length and combustion properties of flares

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Title Improved prediction of buoyancy effects on flame length and combustion properties of flares
Creator Diez, Francisco J.; Dahm, Werner J.A.
Publication type report
Publisher American Flame Research Committee (AFRC)
Program American Flame Research Committee (AFRC)
Date 2004
Description An improved integral method is presented for determining the flame length and combustion properties of buoyant jet flames, including flares, that avoids the Morton entrainment hypothesis entirely and thereby removes the ad hoc "entrainment modeling" required in most other integral approaches. Rather than working with an integral equation for the entrainment rate dm/dx, we use the momentum flux to develop the equation for the local centerline velocity µ,(x). This allows modeling to be done in terms of the local flow width δ(x) ~ x in both the momentum-dominated jet limit and the buoyancy-dominated plume limit, and experiments show the proportionality constant ç to be constant between these limits. The 'entrainment modeling" required in traditional integral methods is thus replaced by the observed constant ç valuse in the integral equation for the buoyancy flux gives an expression for B(x) in terms of the centerline velocity, and provides a simple integral equation for µ (x) that can be readily sloved for arbitrary flare exit conditions by a simple spreadsheet calulation. The resulting µ(x) determines the local mass flux m(x), momentum flux J(x) and buoyancy flux B(x) throughout the flow, as well as the centerline mixture fraction ξ(x) and the flame length L. Comparisons with flame length data show excellent agreement over a wide range of flame conditions, and provides the parameter that characterizes the extent to which buoyancy effects are significant throughout the flame.
Type Text
Format application/pdf
Language eng
OCR Text Show
Metadata Cataloger CLR; AM
ARK ark:/87278/s6227wt0
Relation has part Diez, F. J., & Dahm, W. J.A. (2004). Improved prediction of buoyancy effects on flame length and combustion properties of flares. American Flame Research Committee (AFRC).
Format medium application/pdf
Rights management (c)American Flame Research Committee (AFRC)
Setname uu_afrc
Date Created 2020-02-11
Date Modified 2021-05-06
ID 1525720
Reference URL https://collections.lib.utah.edu/ark:/87278/s6227wt0