NUMERICAL SIMULATION OF INTERNAL FLOW AND CAVITATION OF A DIESEL NOZZLE

Cavitation phenomenon inside a high-pressure diesel nozzle is usually induced by the relative pressure region formed by flow separation along with laminar-turbulent transition. In the present paper, the k-ω SST two-equation turbulence model and k-kl-ω turbulence model taking account of laminar-turbulent transition were employed to simulate the non-cavitation and cavitation flow in a diesel nozzle. Compared with the k-ω SST model that disregards the laminar-turbulent transition effects and accordingly fails to predict the incipient cavitation, the k-kl-ω turbulent model predicted the location and shape of incipient cavitation bubble well with the experimental results, as well as the mass flow rate at the nozzle outlet. Further, the internal flow characteristics, including the length of recirculation region, pressure, fluctuation energy distributions, were investigated utilizing the k-kl-ω model, which provides the insight of liquid fuel jet atomization phenomena and corresponding mechanism.