Velocity field analysis of the high density, high pressure diesel spray

• The PIV study traces droplets through the scattering signal, without flow seeding.
• The effect of injection pressure and ambient air density on velocity profiles is studied.
• A comparison to a similar study, in which flow is seeded, is presented.
• A comparison to a 1D model is presented.
• Transverse cut profiles of axial velocity are evaluated for self-similarity.

In this study, particle image velocimetry (PIV) measurements have been performed extensively on a non-reactive dense diesel spray injected from a single orifice injector, under various injection pressure and steady ambient conditions, in a constant flow chamber. Details of PIV setup for diesel spray measurement without additional seeding are explained first. The measured velocity profiles are compared to those obtained from other similar measurements performed in a different institution, as well as those obtained from a 1D spray model simulation, presenting in both cases a good level of agreement. In addition, the velocity fields under various injection pressures and ambient densities show the dominant effects of these parameters on the behavior of diesel spray. The self-similarity of the transverse cut profiles of axial velocity is evaluated, showing that the measurements are in agreement with the hypothesis of self-similar velocity profiles. Finally, the effect of injection pressure and ambient density on the velocity fluctuations is presented and analyzed as well. While the experimental results presented here could help to understand the complex diesel fuel–air mixing process during injection, they also provide additional spray velocity data for future computational model validation, following the main idea of the Engine Combustion Network.