LES numerical study on in–injector cavitating flow

摘要

In this paper a computational study on hexane flow in a fuel injector is presented. Large Eddy Simulation (LES) was usedto capture the turbulent patterns present in the flow. The main aim was to investigate the cavitation phenomenon and itsinteraction with turbulence as well as the influence of injection pressure and backpressure on fuel mass flow and flow conditions.Analysis of the approach to define the outlet boundary conditions in terms of convergence time and fluid mass outflowoscillations formed a crucial part of the study. Numerical simulations were performed with AVL Fire CFD (Computational FluidDynamics) software. The Euler-Euler approach and multifluid model for multiphase flow modelling were applied. Injectorneedle movement was included in the simulation. Results show that the additional volumes attached to the nozzle outletsimproved the convergence of the simulations and reduced mass outflow oscillations. Fuel mass flow at the outlets was dependenton inlet pressure, position of the needle and backpressure, while the influence of backpressure on fuel mass flow wasnegligible. The presence of the vapor phase at the exit of the nozzles did not affect average fuel mass flow. All the simulationsshowed interaction between the gaseous phase distribution and the turbulence of the flow.