Simulation Of The Internal Flow Characteristic OfDiesel Injector Using CFD Software

Fuel injectors deliver fuel to cylinders of internal combustion (IC) engines. The fuel is
sprayed through an injector nozzle, typically at high pressure, to improve the mixing of
fuel with air and increase the combustion efficiency. Modern passenger cars and trucks
use higher injection pressures than earlier models to improve the atomization of fuel in
order to reduce the emission levels ofIC engines. Unfortunately, high operating pressures
in diesel injectors can cause cavitation in the liquid fuel, leading to degradation in
performance and structural damage to the injector. Because fuel injectors are typically
small, experimental measurements of this phenomenon are difficult to make, so analysis
through CFD is an appealing alternative.
The project scope is mainly on the comparing the simulation results with experimental
data (using a scaled up model). In particular, it is of interest to study the flow behaviour
especially in determining the cavitation and atomization using CFD software, ANSYS
6.0. The methodology of project work consists of literature review, Gantt chart and
simulation.
The main objective of this project is to do simulation on internal flow of diesel fuel
injector using ANSYS, then comparing and analysing the results for both experiment and
simulation. Interpretation from the simulationresults lead to the better explanation for the
cavitation and atomisation phenomena. Finally, at the end of this project the
computational cost can be reduced by the simplification ofsimulation process.
The simulations cover on the single-phase and 2 dimensional analyses which focus on the
effect of the sharp and blunt inlet nozzle to the cavitation flow. Meanwhile, for the
atomization and hydraulic flip flow, volume fraction analysis will be the best method to
express the atomization flow as explain in the chapter 2. As conclusion for this project,
ANSYS software is reliable to simulate the internal fluid flow problems and able to
produce a quite accurate outcome (with some limitation) to assist in further study on the
internal fluid flow behaviour.