Numerical investigation of nozzle shape and angle orientation changing effects on fuel atomization characteristics

Various cavitation regimes which occur in a nozzle of fuel injector play a dominant role in the fuel spray atomization process and the subsequent spray combustion quality. In this paper, the effect of cavitating flow on fuel atomization characteristics in nozzles of different length to width (L/W) ratios and also different angel orientations was numerically investigated. All of the simulations were carried out in the present paper are based on the Eulerian multiphase model and the Reynolds-Averaged Navier-Stokes (RANS) turbulence model of k-e and solving of promoted Rayleigh-Plesset (RP) equation to simulate an incipient cavitation. A precursor simulation of a fully developed turbulent flow in a channel, in which periodic boundary condition is adopted for the inlet and outlet, is carried out to generate inlet boundary condition for a nozzle simulation. The results of this study show that, for the nozzles with higher length to width (L/W) ratio, larger mass flow rates can be used for fuel injection into combustion chamber without occurring hydraulic flip at the outlet of nozzle which will cause Inappropriate fuel spray in the other words pure fuel flipping jet. Also results indicate changing angle orientation and locations of considered special shape of nozzle around cylinder chiefly at lower velocities causes different outlet void fraction profile at the same inlet velocity profiles which directly influence on the fuel atomization characteristics.