Authors:   S. Dooley, S. H. Won, J. Heyne, T. Farouk, F. L. Dryer, Y. Ju, K. Kumar, X. Hui, C. J. Sung, H. Wang, M. A. Oehlschlaeger, R. J. Santoro, T. A. Litzinger, V. Iyer, T. Malewicki, and K. Brezinsky
Direct link to the paper:   http://dx.doi.org/10.1016/j.combustflame.2011.11.002
Abstract:

Amethodology for the formulation of surrogatefuels for the emulation of realfuelgasphasecombustionkineticphenomena pertinent to gas turbine combustion is described and tested. A mixture of n-dodecane/iso-octane/1,3,5-trimethylbenzene/n-propylbenzene is formulated in a predictive manner to exhibit the same gasphasecombustionphenomena of a target Jet-Afuel by the sharing of fundamentally significant combustion property targets in addition to a prescribed commonality of chemical kinetically controlling intermediate species. The appropriateness of the surrogateformulation technique is demonstrated by the experimental measurement of various gasphasecombustionkineticphenomena of the proposed surrogate mixture and of the target Jet-Afuel:

(1)

A variable pressure flow reactor is used to chart the chemical reactivity of a stoichiometric mixture of surrogatefuel/O₂/N₂ at 12.5 atm and 500–1000 K, for a residence time of 1.8 s at a fixed carbon content of 0.3%.

(2)

The autoignition behavior of stoichiometric mixtures of surrogatefuel in air is measured with a shock tube at 667–1223 K at ∼20 atm and also with a rapid compression machine at 645–714 K at compressed pressures of 21.7 atm.

(3)

Detailed measurements of the intermediate species formed in the high temperature oxidation of the target fuel and in the oxidation of the surrogatefuel are performed with a shock tube for reaction times of 1.23–3.53 ms at 18–35 atm and 901–1760 K for 0.0808/0.158/0.1187 mole% mixtures of C/H/O₂.

(4)

The laminar burning velocity and strain extinction limits of premixed mixtures of surrogatefuel in O₂/N₂ are determined by the counter flow twin flame technique. These phenomena are also determined for premixed mixtures of the target fuel and for a previously proposed surrogatefuel composed of n-decane/iso-octane/toluene in O₂/N₂.

(5)

The high temperature chemical reactivity and chemical kinetic–molecular diffusion coupling of the surrogatefuel is evaluated by measurement of the strained extinction limits of diffusion flames.

(6)

The propensity of surrogate and realfuel to form soot is tested by laser extinction measurements of the soot volume fractions formed by each fuel in a wick-fed laminar flame diffusion burner as a function of the radial distance of each flame.

 

These experimental data are compared to those previously reported at identical conditions for the target Jet-Afuel and for a similar n-decane/iso-octane/toluene surrogatefuel. A conceptual theory of realfueloxidation is proposed and the similarity of the exhibited combustionphenomena of all three fuels is analyzed and interpreted in this context in order to (a) further evaluate the proposed strategy to surrogatefuelformulation and the appropriateness of the proposed theory to realfueloxidation, (b) evaluate the appropriateness of the proposed n-dodecane/iso-octane/1,3,5-trimethylbenzene/n-propylbenzene mixture as asurrogatefuel for the target Jet-Afuel, and (c) to provide direction for the development of a tractable numerical modeling framework to compute realfuel multiphase combustionphenomena.

Citation:   S. Dooley, S. H. Won, J. Heyne, T. Farouk, F. L. Dryer, Y. Ju, K. Kumar, X. Hui, C. J. Sung, H. Wang, M. A. Oehlschlaeger, R. J. Santoro, T. A. Litzinger, V. Iyer, T. Malewicki, and K. Brezinsky, “The Experimental Evaluation of a Methodology to Surrogate Fuel Formulation for the Emulation of Gas Phase Combustion Kinetic Phenomena by a Theory of Real Fuel Oxidation,” Combustion and Flame 159 (4), 1444-1466 (2012).