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This paper deals with the integrated modeling of a multiple injection common rail system. The aim of the numerical investigation is to capture the behavior of the multiple injections, in terms of electro-injector dynamic and nozzle flow development. In detail, the multiple injection investigation focuses on the transient phenomena of the injector, in order to evaluate their role on the definition of two aspects of the injection strategy, the fuel rate time evolution and their influence on the nozzle flow features. The model is based on the integration of two different commercial codes. In the simulations, a 0/1-D code has been used to analyze the complete injection system. The results obtained from the injection system simulation, in terms of injection needle lift, injection flow rate, pressure time evolution, have been used as boundary conditions for the 3-D CFD computation tool, in which the numerical investigation of the internal injector flow has been performed.

This paper deals with the numerical investigation of a Diesel engine high pressure DI system in which the influence of needle motion characteristics on the internal injector flows is evaluated; a radial perturbation of the axial needle motion has been imposed to analyze its role over the nozzle flow features. The developed model is based on the coupling of two computational tools. With the former one, AMESim code, the injector has been modeled; the results obtained from the injector simulation, in terms of injection needle lift time evolution, have been used to initialize the latter computation tool, FIRE code, in which 3D flow numerical investigation of the internal injector flows has been performed. Details of the adopted modeling strategy are presented and the results of each simulation step are shown.

Diesel particulate filters are well known for their efficiency and reliability in trapping particulate matter out of diesel engines. In the last years, many efforts have been done to improve their performances, leading to the employment of new materials and architectures, as well as sophisticated regeneration and management strategies. A lumped parameter model has been developed by the authors able to ensure good accuracy and fast processing for DPF control applications. In this paper, the attention is at first addressed towards the loading process; the evolution with time of pressure drop inside the filter structure is computed and basing on the engine operative condition, a parametrization of the deposited soot layer profile is proposed, in which the effect of the flow distribution at the cross section of the filter is accounted for. The regeneration process is then investigated and temperature profile inside the filter channel is analyzed.

Many efforts are being currently devoted to the development of diagnostic techniques based on nonintrusive measurements aimed at defining the injection parameters able to optimize the combustion process. Previous papers of the authors have demonstrated a direct relationship between in-cylinder pressure and engine block vibration signals. Besides, it was also shown sensitivity of the engine surface vibration to variation of injection parameters, when the accelerometer is placed in sensitive location of the engine block. Moreover, in the accelerometer signal, a frequency band in which such a relationship is very strict has been selected. The aim of the present work is to establish a reliable relation between the main characteristics of the in-cylinder pressure curve and the vibration trend, by means of a deeper insight into the engine block signal. The final objective is to monitor the combustion behavior by means of a non-intrusive transducer.

The performances of high pressure fuel-injection systems and their effects on diesel engine combustion are strongly influenced by the injector characteristics and the set up of the whole equipment control system. High-pressure system based on the common-rail architecture allows a multi-stage injection, which is of paramount importance in controlling combustion noise, fuel consumption, operation roughness and exhaust pollutant emissions. Common rail fuel injection equipment for automotive diesel engine, together with its control system have been analysed by using AMESim environment; both standard library elements and self-developed sub-models have been adopted. At first the different components have been considered one by one; in this way the behaviour of high pressure pump (radial-jet), pressure regulator, rail, injectors, system control (e. c. u.) has been investigated; the results have been compared with experimental measurements.

An integrated numerical procedure has been developed in order to predict the noise radiation of small engine for automotive and general purpose applications. In exhaust system of single or multi-cylinder small engine, complex shape elements are always included (junction, compact chamber), where non-planar higher-order modes exist. Besides, the amplitude of pressure wave, propagating inside such exhaust systems, is generally not bounded by linear acoustic limit. For these reasons, aimed at providing realistic and accurate description of their fluid dynamic and acoustic behaviour, an integrated multi-code methodology, based on 0D, 1D and 3D models, has been set up; the investigation of the flow conditions all throughout the exhaust system, allows to predict the sound emission.