Spray measurements and numerical analysis on an impinging jet injector

The spray characteristics of an impinging jet injector have been investigated experimentally and numerically. The droplet size distribution, the velocity and the mass flux distribution were measured using Phase-Doppler Anemometry (PDA), and approximated to distribution functions in order to obtain the input data for the numerical simulation by KIVA-3 V. The simulation indicated that the effects of turbulent dispersion on the behavior of droplets must be included in the numerical model. The local droplet size distribution is dominated by the turbulence intensity, because small droplets tend to be transported by the drag of surrounding turbulent gas flow, while the trajectories of large ones are almost straight. Computational grid sizes are also important factor because the turbulence intensity strongly depends on the radial width. Simulations with coarse grids resulted in poor predictions, in which the turbulence intensity was overestimated. It is important to choose proper grid sizes with considering the balance of the accuracy and the computational cost.