Nonlinear modelling and control of a common rail injection system for diesel engines

Investigation of Diesel Spray Primary Break-up and Development for Different Nozzle Geometries

This article details a method for modelling the most critical parts of an injection system. It focuses on the most important component of the system, the injector itself. As a clear example of this methodology, the modelling of a first-generation common rail injection system is carried out using a commercial code. The proposed methodology for modelling the injection system is based on two types of characterization: a detailed dimensional characterization and a hydraulic characterization of the different internal parts of the injector. The dimensional characterization is based on the use of a fine detail measuring technique applied to all the constituents of the injector. These include the passages and internal lines of the injector, internal volumes, calibrated orifices, nozzle springs, clearances between moving sections of pistons, etc. The second type of characterization makes reference mainly to the hydraulic characterization of the nozzle and injector control orifices, which together with dime...

Diesel Injection System Modelling. Methodology and Application for a First-generation Common Rail System:

The aim of this work is to set up a methodology for simulating Common Rail high-pressure injectors based on coupling a lump-model with CFD two-phase multi-dimensional computations. The unit simulated is the Bosch injector. The injector lump-model resulted in the definition of the three sub-models for hydraulics, mechanics and electromagnetics. The second-order differential governing equations have been solved in Matlab/Simulink environment and are properly coupled together with the one-dimensional partial differential equations that describe the unsteady pipe flow. A detailed library of thermo-mechanical properties for ISO-4113 oil and diesel fuel is included. Cavitation effects on discharge coefficient in the main orifices were accounted for by using results from CFD steady two-phase flow simulations. The evaluation of the model capability was assessed by using detailed experiments carried out at different practical injector operating conditions. Instantaneous and integrated injected flow rate, and injector needle lift were measured and collected for comparison with simulation. CFD steady computations revealed to be unavoidable in driving the lump-model toward a high reliability of injector performances over the whole range of injection pressures and energizing times.

V. Landriscina

Papers

Evaluation of Instability Phenomena in a Common Rail Injection System for High Speed Diesel Engines