| NUMERICAL MODELING FOR N-HEPTANE SPRAY COMBUSTION PROCESSES WITH VARIOUS AMBIENT OXYGEN CONCENTRATIONS |
| Kiyoung Jung1, Minjun Kwon2, Sewon Kim2, Sungwook Park1, Yongmo Kim1 |
1Hanyang University
2KITECH |
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| ABSTRACT |
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This work has numerically analyzed the structure of spray flames with various ambient oxygen concentrations.
To realistically predict the spray evaporation characteristics in the high-pressure diesel-like environment, the present study has
employed the high-pressure effective conductivity vaporization model. The detailed n-heptane/air chemistry is represented by
114 elementary steps and 44 chemical species. The Representative Interactive Flamelet (RIF) model is adopted to consider the
interactions between turbulence and chemistry in the fast transient reacting flows. In order to account for the spatial
inhomogeneity of the scalar dissipation rate, the multiple RIFs are introduced. Moreover, the present approach realistically
models the vaporization effects on the mixture fraction fluctuations. For the various conditions of ambient oxygen
concentration, numerical results are compared with experimental data including the ignition delay and the lift-off length. These
results indicate that the present MRIF approach yields the reasonably good agreement with experimental data in terms of
ignition delay time and lift-off length. To gain the physical insight into the two-stage ignition behavior of diesel fuels, the
detailed discussions are also made for the temporal evolution of several key species (CH2O, OH, CO) mass fraction and
maximum temperature of the transient flamelet as well as the flame stabilization mechanism of the n-heptane spray flames
with the much lower ambient oxygen concentration. |
| Key Words:
High-pressure evaporation model, Multiple representative interactive flamelet model, Spray-H, Two-stage
ignition, Effects of ambient oxygen concentration |
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Corresponding Author.
Yongmo Kim , Email. 
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