A Numerical Simulation of Turbulent Mixing in Transient Spray by LES (Comparison between Numerical and Experimental Results of Transient Particle Laden Jets)

The purpose of this study is to investigate the turbulent mixing in a diesel spray by large eddy simulation (LES). As the first step for the numerical simulation of diesel spray by LES, the LES of transient circular gas jets and particle laden jets were conducted. The simulation of transient circular jets in cylindrical coordinates has numerical instability near the central axis. To reduce the instability of calculation, azimuthal velocity around the central axis is calculated by the linear interpolation and filter width around the axis is modified to the radial or axial grid scale level. A transient circular gas jet was calculated by the modified code and the computational results were compared with experimental results with a Reynolds number of about 13000. The computational results of mean velocity and turbulent intensity agreed with experimental results for z/D>10. Predicted tip penetration of the jet also agreed to experimental data. Next, the simulations of transient circular particle laden jets were performed at the mass loading ratios of particles of 0.13 and 0.8. The particles were glass beads and the Sauter mean diameter of beads was 0.035 mm. Prediction underestimated the turbulent intensity of particles and overestimated the length of potential core. When the mass loading of particles increased, the discrepancy between predicted and experimental results increased.