Search Results

The onset of cavitating conditions inside the nozzle of diesel injectors is known to play a major role on spray characteristics, especially on jet penetration and break-up. In this work, for the first time a Direct Numerical Simulation (DNS) based on the Lattice Boltzmann Method (LBM) is applied to study the fluid dynamic field inside the nozzle of a cavitating diesel injector. The formation of the cavitating region is determined via a multi-phase approach based on the Shan-Chen Equation of State and its most recent enhancements. The evolution of cavitation bubbles is followed and the characteristic numbers, i.e., Cavitation Number (CN) and discharge coefficient (Cd) are evaluated. The results obtained by the LBM simulation are compared to both numerical and experimental data present in literature.

Spray formation and break-up are crucial phenomena for mixture formation inside diesel engines, both for combustion control and pollutant formation. Since the emission restrictions have become more and more severe in the last years, many studies have been conducted in order to improve diesel injection. Numerical simulations have proven to be reliable in producing results in a faster and cheaper way than experimental measures. The recent great progresses in computer science, then, have allowed to reach great accuracy in the simulations. In this work, a novel methodology based on Boltzmanns Kinetic Theory is applied to diesel injection. Lattice Boltzmann BGK (LBGK) provides and alternative method for solving fluid-dynamic problems and allows even superior accuracy as compared to conventional CFD. The multiphase approach used in this paper to study spray formation and primary is based on the works by Shan and Chen and their successive modifications.