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The startability of SI engines, especially of DISI engines, is the greatest challenge when using ethanol blended fuels. The development of a suitable injection strategy is therefore the main engineering target when developing an ethanol engine with direct injection. In order to limit the test efforts of such a program, a vaporization model has been created that provides the quantity of vaporized fuel depending on pressure and on start and end, respectively number and split relation of injections. This model takes account of the most relevant fuel properties such as density, surface tension and viscosity. It also considers the interaction of the spray with cylinder liner, cylinder head and piston. A comparison with test results shows the current status and the need for action of this simulation model.

A detailed analysis of knocking events can help improving engine performance and diagnosis strategies. The paper aim is a better understanding of the phenomena involved in knocking combustions through the combination of CFD and signals analysis tools. CFD simulations have been used in order to reproduce knock effect on the in-cylinder pressure trace. In fact, the in-cylinder pressure signal holds information about waves propagation and heat losses: for the sake of the diagnosis it is important to relate knock severity to knock indexes values. For this purpose, a CFD model has been implemented, able to predict the combustion evolution with respect to Spark Advance, from non-knocking up to heavy knocking conditions. The CFD model validation phase is crucial for a correct representation of both regular and knocking combustions: the operation has been carried out by means of an accurate statistical analysis of experimental in-cylinder pressure data.

Fluid filled bushings are commonly used in vehicle suspension and sub-frame systems due to their spectrally-varying and amplitude-dependent properties. Since the literature on this topic is sparse, a controlled laboratory prototype bushing is first designed, constructed, and instrumented. This device provides different internal combination of long and short flow passages and flow restriction elements. Experiments with sinusoidal displacement excitations are conducted on the prototype, and dynamic stiffness spectra along with fluid chamber pressure responses are measured. The frequency-dependent properties of several commonly seen hydraulic bushing designs are experimentally studied and compared under two excitation amplitudes. Further, new linear time-invariant models with one long and one short flow passages (in parallel or series) are proposed along with the limiting cases.

The acoustic and performance characteristics of an automotive centrifugal compressor are studied on a steady-flow turbocharger test bench, with the goal of advancing the current understanding of compression system instabilities at the low-flow range. Two different ducting configurations were utilized downstream of the compressor, one with a well-defined plenum (large volume) and the other with minimized (small) volume of compressed air. The present study measured time-resolved oscillations of in-duct and external pressure, along with rotational speed. An orifice flow meter was incorporated to obtain time-averaged mass flow rate. In addition, fast-response thermocouples captured temperature fluctuations in the compressor inlet and exit ducts along with a location near the inducer tips.

In the near future, emissions legislation will become more and more restrictive for direct injection SI engines by adopting a stringent limitation of particulate number emissions in late 2017. In order to cope with the combustion system related challenges coming along with the introduction of this new standard, Hitachi Automotive Systems Ltd., Hitachi Europe GmbH and IAV GmbH work collaboratively on demonstrating technology that allows to satisfy EU6c emissions limitations by application of Hitachi components dedicated to high pressure injection (1). This paper sets out to describe both the capabilities of a new high pressure fuel system improving droplet atomization and consequently mixture homogeneity as well as the process of utilizing the technology during the development of a demonstrator vehicle called DemoCar. The Hitachi system consists of a fuel pump and injectors operating under a fuel pressure of 30 MPa.

This work focuses on the development and validation of a data-driven model capable of predicting the maximum in-cylinder pressure during the operation of an internal combustion engine, with the least possible computational effort. The model is based on two parameters, one that represents engine load and another one the combustion phase. Experimental data from four different gasoline engines, two turbocharged Gasoline Direct Injection Spark Ignition, a Naturally Aspirated SI and a Gasoline Compression Ignition engine, was used to calibrate and validate the model. Some of these engines were equipped with technologies such as Low-Pressure Exhaust Gas Recirculation and Water Injection or a compression ignition type of combustion in the case of the GCI engine. A vast amount of engine points were explored in order to cover as much as possible of the operating range when considering automotive applications and thus confirming the broad validity of the model.

The next steps of the current European and US legislation, EURO 6c and LEV III, and the incoming new test cycles will impose more severe restrictions on pollutant emissions for Gasoline Direct Injection (GDI) engines. In particular, soot emission limits will represent a challenge for the development of this kind of engine concept, if injection and after-treatment systems costs are to be minimized at the same time. The paper illustrates the results obtained by means of a numerical and experimental approach, in terms of soot emissions and combustion stability assessment and control, especially during catalyst-heating conditions, where the main soot quantity in the test cycle is produced. A number of injector configurations has been designed by means of a CAD geometrical analysis, considering the main effects of the spray target on wall impingement.

Metallic foams or sponges are materials with a cell structure suitable for many industrial applications, such as reformers, heat catalytic converters, etc. The success of these materials is due to the combination of various characteristics such as mechanical strength, low density, high specific surface, good thermal exchange properties, low flow resistance and sound absorption. Different materials and manufacturing processes produce different type of structure and properties for various applications. In this work a genetic algorithm has been developed and applied to support the design of catalytic devices. In particular, two substrates were considered, namely the traditional honeycomb and an alternative open-cell foam type. CFD simulations of pressure losses and literature based correlations for the heat and mass transfer were used to support the genetic algorithm in finding the best compromise between flow resistance and pollutant abatement.

In this study, an adaptive control mechanism is proposed to design a silencer applying variable volume resonator concept. Transfer matrix method is used to calculate the transmission loss and evaluate acoustic performance of the proposed mechanism. Effects of damping factor, area ratio of expansion chambers are examined first for a fixed double chamber resonator. Then a two-dimensional search scheme is developed to find optimal piston position that achieves maximum transmission loss with minimal effort. This study shows that the proposed adaptive silencer can efficiently attenuate noise when comparing with a conventional fixed resonator.

Fuels are formulated by a variety of different components characterized by chemical and physical properties spanning a wide range of values. Changing the ratio between the mixture component molar fractions, it is possible to fulfill different requirements. One of the main properties that can be strongly affected by mixture composition is the volatility that represents the fuel tendency to vaporize. For example, changing the mixture ratio between alcohols and hydrocarbons, it is possible to vary the mixture saturation pressure, therefore the fuel vaporization ratio during the injection process. This paper presents a 1D numerical model to simulate the superheated injection process of a gasoline-ethanol mixture through real nozzle geometries. In order to test the influence of the mixture properties on flash atomization and flash evaporation, the simulation is repeated for different mixtures characterized by different gasoline-ethanol ratio.

Zero-dimensional heat release rate models have the advantage of being both easy to handle and computationally efficient. In addition, they are capable of predicting the effects of important engine parameters on the combustion process. In this study, a zero-dimensional combustion model based on physical and chemical sub-models for local processes like injection, spray formation, ignition and combustion is presented. In terms of injection simulation, the presented model accounts for a phenomenological nozzle flow model considering the nozzle passage inlet configuration and an approach for modeling the characteristics of the Diesel spray and consequently the mixing process. A formulation for modeling the effects of intake swirl flow pattern, squish flow and injection characteristics on the in-cylinder turbulent kinetic energy is presented and compared with the CFD simulation results.

The purpose of this paper is to present some innovative techniques developed for an unconventional utilization of currently standard exhaust sensors, such as HEGO, UEGO, and NOx probes. In order to comply with always more stringent legislation about pollutant emissions, intake-exhaust systems are becoming even more complex and sophisticated, especially for CI engines, often including one or two UEGO sensors and a NOx sensor, and potentially equipped with both short-route and long-route EGR. Within this context, the effort to carry out novel methods for measuring the main exhaust gas dynamic properties exploiting sensors installed for different purposes, could be useful both for control applications, such as EGR rates estimation, or cost reduction, minimizing the on-board devices number. In this work, a gray-box model for measuring the gas mass flow rate, based on standard NOx sensor operating parameters of its heating circuit, is analyzed.

This work focuses on the effects of cooled Low Pressure EGR and Water Injection observed by conducting experimental tests consisting mainly of Spark Advance sweeps at different cooled LP-EGR and WI rates. The implications on combustion and main engine performance indexes are then analysed and modelled with a control-oriented approach, showing that combustion duration and phase and exhaust gas temperature are the main affected parameters. Results show that cooled LP-EGR and WI have similar effects, being the associated combustion speed decrease the main cause of exhaust gas temperature reduction. Experimental data is used to identify control-oriented polynomial models able to capture the effects of LP-EGR and WI on both these aspects. The limitations of LP-EGR are also explored, identifying maximum compressor volumetric flow and combustion stability as the main ones.

Previously we had found significant errors in the interfacial force results for a source-path-receiver system where only translational motions were measured. This paper examines the sources of those errors by using computational finite and boundary element models. The example case consists of a source structure (with few modes), a receiver (with many modes) and three steel rod paths. We first formulate indirect, yet exact, methods for estimating interfacial forces, by assuming that six-dimensional motions at any location are available though we focus on only the driving points. One- and three-dimensional sub-sets of the proposed formulation are compared with the six-dimensional theory in terms of interfacial force and partial sound pressure spectra.

In-cylinder charge motion is known to significantly increase turbulence intensity, accelerate combustion rate, and reduce cyclic variation. This, in turn, extends the tolerance to exhaust gas recirculation (EGR), while the introduction of EGR results in much lowered nitrogen oxide (NOx) emissions and reduced fuel consumption. The present study investigates the effect of charge motion in a spark ignition engine on fuel consumption, combustion, and engine-out emissions with stoichiometric and EGR-diluted mixtures under part-load operating conditions. Experiments have been performed with a Chrysler 2.4L 4-valve I4 engine under 2.41 bar brake mean effective pressure at 1600 rpm over a spark range around maximum brake torque timing. The primary intake runners are partially blocked to create different levels of tumble, swirl, and cross-tumble (swumble) motion in the cylinder before ignition.

External gear pumps are widely used in many different applications because of their relatively low costs and high performances, especially in terms of volumetric and mechanical efficiency. The main weaknesses of external gear pumps can be summarized as follows: 1 Sudden increase or decrease of pressure inside volumes between teeth, which could lead respectively to noise emissions and to cavitation onset; 2 Necessity of limiting power losses and increasing volumetric efficiency, obtainable by reducing leakage flows between components; 3 Need of maintaining an ad-hoc minimum lubrication film thickness. In recent years many efforts, in terms of mathematical models and experimental tests, were done in order to limit energy losses and noise emissions. With the aim of deeply studying dynamic behaviour of external gear pumps and addressing their design, a 1D model was developed by means AMESim® code.

In order to satisfy environmental regulations while maintaining strong performance and excellent fuel economy, advanced diesel engines are employing sophisticated air breathing systems. These include high pressure and low pressure EGR (Hybrid EGR), intake and exhaust throttling, and variable turbine geometry systems. In order to optimize the performance of these sub-systems, system level controls are necessary. This paper presents the design, benefits and test results of a model-based air system controller applied to an automotive diesel engine.

Specific power and efficiency of gasoline engines are influenced by factors such as compression ratio and Spark Advance (SA) regulation. These factors influence the combustion development over the crank angle: the trade-off between performance and the risk of irreversible damages is still a key element in the design of both high-performance (racing) and low-consumption engines. This paper presents a novel approach to the problem, with the objective of defining a damage-related and operating conditions-independent index. The methodology is based on the combined analysis of indicating parameters, such as Cumulated Heat Release (CHR), Indicated Mean Effective Pressure (IMEP) and 50% Mass Fraction Burned (MFB50), and typical knock detection parameters, estimated by means of the in-cylinder pressure sensor signal. Knocking combustions have several consequences, therefore they can be detected in many ways.

During a motor-vehicle collision, an occupant may interact with a variety of interior structures. The material properties and construction of these structures can directly affect the occupant's kinetic response. Simulation tools such as MADYMO (Mathematical Dynamical Models) can be used to estimate the forces imparted to an occupant for injury mechanism and causation evaluation relative to a particular event. Depending on the impact event and the specific injury mechanism being evaluated, the selection of proper material characteristics can be quite important. A comprehensive literature review of MADYMO studies illustrates the prevalent use of generic material characteristics and the need for improved property estimation and implementation methods.

This study investigates the autoignition of Primary Reference Fuels (PRFs) using a detailed kinetic model. The chemical kinetics software CHEMKIN is used to facilitate solutions in a constant volume reactor and a variable volume reactor, with the latter representing an IC engine. Experimental shock tube and HCCI engine data from literature is compared with the present predictions in these two reactors. The model is then used to conduct a parametric study in the constant volume reactor of the effect of inlet pressure, inlet temperature, octane number, fuel/air equivalence ratio, and exhaust gas recirculation (EGR) on the autoignition of PRF/air mixtures. A number of interesting characteristics are demonstrated in the parametric study. In particular, it is observed that PRFs can exhibit single or two stage ignition depending on the inlet temperature. The total ignition delay, whether single or two stage, is correlated withn-C7H16/O2 ratio.