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The increasing power demand in vehicles has resulted in a need for a higher onboard generation capacity. With the increasing generation requirement, the torque levels of the generator are found to closely converge with that of the starter motor. Hence, integrating the two machines and using a single machine for the two purposes would be technically viable and economically advantageous. This results in a more compact design solution as well. The Integrated Starter/Alternator (ISA) will be integrated directly to the crankshaft of the Internal Combustion Engine (ICE) and deliver 5 kW average and 12-15 kW peak power at 42V.

Low speed pre-ignition (LSPI) in downsized spark-ignition engines has been studied for more than a decade but no definitive explanation has been found regarding the exact sources of auto-ignition. No single mechanism can explain all the occurrences of LSPI and that each engine should be considered as a particular case supporting different conditions for auto-ignition. In a different context, dual fuel Diesel-Methane engines have been more recently studied in large to medium bore compression ignition engines. However, if Dual Fuel combustion is less knock sensitive, LSPI remains one of the main limitations of low-end torque also for dual fuel engines. Indeed, in some cases, premature ignition of CNG can be observed before the Diesel pilot injection as LSPI can classically be observed before the spark in gasoline engines. This article aims at highlighting the similarities and discrepancies between LSPI phenomena in SI gasoline and dual fuel engines.

Modeling plume interaction and collapse for direct-injection gasoline sprays is important because of its impact on fuel-air mixing and engine performance. Nevertheless, the aerodynamic interaction between plumes and the complicated two-phase coupling of the evaporating spray has shown to be notoriously difficult to predict. With the availability of high-speed (100 kHz) Particle Image Velocimetry (PIV) experimental data, we compare velocity field predictions between plumes to observe the full temporal evolution leading up to plume merging and complete spray collapse. The target “Spray G” operating conditions of the Engine Combustion Network (ECN) is the focus of the work, including parametric variations in ambient gas temperature. We apply both LES and RANS spray models in different CFD platforms, outlining features of the spray that are most critical to model in order to predict the correct aerodynamics and fuel-air mixing.

Striving for sustainable transportation solutions, hydrogen is often identified as a promising energy carrier and internal combustion engines are seen as a cost effective consumer of hydrogen to facilitate the development of a large-scale hydrogen infrastructure. Driven by efficiency and emissions targets defined by the U.S. Department of Energy, a research team at Argonne National Laboratory has worked on optimizing a spark-ignited direct injection engine for hydrogen. Using direct injection improves volumetric efficiency and provides the opportunity to properly stratify the fuel-air mixture in-cylinder. Collaborative 3D-CFD and experimental efforts have focused on optimizing the mixture stratification and have demonstrated the potential for high engine efficiency with low NOx emissions. Performance of the hydrogen engine is evaluated in this paper over a speed range from 1000 to 3000 RPM and a load range from 1.7 to 14.3 bar BMEP.

Traditional Lagrangian spray modeling approaches for internal combustion engines are highly grid-dependent due to insufficient resolution in the near nozzle region. This is primarily because of inherent restrictions of volume fraction with the Lagrangian assumption together with high computational costs associated with small grid sizes. A state-of-the-art grid-convergent spray modeling approach was recently developed and implemented by Senecal et al., (ASME-ICEF2012-92043) in the CONVERGE software. The key features of the methodology include Adaptive Mesh Refinement (AMR), advanced liquid-gas momentum coupling, and improved distribution of the liquid phase, which enables use of cell sizes smaller than the nozzle diameter. This modeling approach was rigorously validated against non-evaporating, evaporating, and reacting data from the literature.

Road vehicles can expend a significant amount of energy in undesirable vertical motions that are induced by road bumps, and much of that is dissipated in conventional shock absorbers as they dampen the vertical motions. Presented in this paper are some of the results of a study aimed at determining the effectiveness of efficiently transforming that energy into electrical power by using optimally designed regenerative electromagnetic shock absorbers. In turn, the electrical power can be used to recharge batteries or other efficient energy storage devices (e.g., flywheels) rather than be dissipated. The results of the study are encouraging - they suggest that a significant amount of the vertical motion energy can be recovered and stored.

The 4th Workshop of the Engine Combustion Network (ECN) was held September 5-6, 2015 in Kyoto, Japan. This manuscript presents a summary of the progress in experiments and modeling among ECN contributors leading to a better understanding of soot formation under the ECN “Spray A” configuration and some parametric variants. Relevant published and unpublished work from prior ECN workshops is reviewed. Experiments measuring soot particle size and morphology, soot volume fraction (fv), and transient soot mass have been conducted at various international institutions providing target data for improvements to computational models. Multiple modeling contributions using both the Reynolds Averaged Navier-Stokes (RANS) Equations approach and the Large-Eddy Simulation (LES) approach have been submitted. Among these, various chemical mechanisms, soot models, and turbulence-chemistry interaction (TCI) methodologies have been considered.

In this paper, a sectional soot model coupled to a tabulated combustion model is compared with measurements from an experimental engine database. The sectional soot model, based on the work of Vervisch-Klakjic (Ph.D. thesis, Ecole Centrale Paris, Paris, 2011) and Netzell et al. (P. Combust. Inst., 31(1):667-674, 2007), has been implemented into IFPC3D (Bohbot et al., Oil Gas Sci Technol, 64(3):309-335, 2009), a 3D RANS solver. It enables a complex modeling of soot particles evolution, in a 3D Diesel simulation. Five distinct source terms are applied to each soot section at any time and any location of the flow. The inputs of the soot model are provided by a tabulated combustion model derived from the Engine Approximated Diffusion Flame (EADF) one (Michel and Colin, Int. J. Engine Res., 2013) and specifically modified to include the minor species required by the soot model.

In this paper, a new physics-based model for the prediction of NOx emissions produced by diesel engines is presented. The aim of this work is to provide a reference model for the validation of control strategies and NOx estimators. The model describes the NOx production in the burned gas zone where the burned gas temperature sub-model is adapted to be generic and tunable. The model consists of three main sub-models for the estimation of the burned gas temperature, the concentration of the species in the burned gases and the NOx formation, respectively. A new model for estimating the burned gas temperature, known to have a strong impact on thermal NOx formation rate, is proposed. The model depends on the intake burned gas ratio and the combustion phasing computed from the cylinder pressure. This model has a limited number of calibration parameters identified so that NOx model output matches with experimental data measured in a four-cylinder, four-stroke, direct-injection diesel engine.

This work presents a simple fan model that is based on the actuator disk approximation, and the blade element and vortex theory of a propeller. A set of equations are derived that require as input the rotational speed of the fan, geometric fan data, and the lift and drag coefficients of the blades. These equations are solved iteratively to obtain the body forces generated by the fan in the axial and circumferential directions. These forces are used as momentum sources in a CFD code to simulate the effect of the fan in an underhood thermal management simulation. To validate this fan model, a fan experiment was simulated. The model was incorporated into the CFD code STAR-CD and predictions were generated for axial and circumferential air velocities at different radial positions and at different planes downstream of the fan. The agreement between experimental measurements and predictions is good.

In an effort of providing better understanding of regeneration mechanisms of diesel particulate matter (PM), this experimental investigation focused on evaluating the amount of heat release generated during the thermal reaction of diesel PM and the concentrations of soluble organic compounds (SOCs) dissolved in PM emissions. Differences in oxidation behaviors were observed for two different diesel PM samples: a SOC-containing PM sample and a dry soot sample with no SOCs. Both samples were collected from a cordierite particulate filter membrane in a thermal reactor connected to the exhaust pipe of a light-duty diesel engine. A differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TGA) were used to measure the amount of heat release during oxidation, along with subsequent oxidation rates and the concentrations of SOCs dissolved in particulate samples, respectively.

For several years there has been a great deal of effort made in researching ways to run a compression ignition engine with simultaneously high efficiency and low emissions. Recently much of this focus has been dedicated to using gasoline-like fuels that are more volatile and less reactive than conventional diesel fuel to allow the combustion to be more premixed. One of the key challenges to using fuels with such properties in a compression ignition engine is stable engine operation at low loads. This paper provides an analysis of how stable gasoline compression ignition (GCI) engine operation was achieved down to idle speed and load on a multi-cylinder compression ignition engine using only 87 anti-knock index (AKI) gasoline. The variables explored to extend stable engine operation to idle included: uncooled exhaust gas recirculation (EGR), injection timing, injection pressure, and injector nozzle geometry.

Adaptive Cycle Engines, where compression and expansion events do not follow a fixed sequence but rather take place depending on demand, are competitive against electric motors because of their higher power density, lower carbon footprint with current energy sources, and predicted ability to use any kind of renewable fuel. The advantage of Adaptive Cycle Engines is greater whenever the powerplant has at least two distinct operating modes: one for high output, and one for high energy economy. This paper compares the well-to-wheels CO2 emissions and pre-tax costs when operating powerplants based on Adaptive Cycle Engines and on electric motors under several scenarios: passenger car, on-road heavy-duty vehicle, and light aircraft.

A more accurate combustion model, based on Fluent simulations including the effect of flame stretching and extinction, has been added to cycle and road simulations of an Adaptive Cycle Engine (ACE), where compressions and expansions do not follow a predefined sequence. Also, engine speed data from the Argonne Downloadable Dynamometer Database is used in the road simulations in lieu of the original constant-speed model. Results show a drop in predicted steady-state brake efficiency and bmep around 15% relative to the model using a standard Wiebe function for heat release rate. Performance on road cycles is not greatly affected by the delayed combustion since the relationship between expansion mass and work is largely unchanged. Even with the refined model, future ACE-equipped vehicles are expected to be competitive with electric powertrains in pre-tax cost and overall emissions.

The air entrainment process of diesel-like gas jet was studied by simultaneous measurements of concentration and velocity fields. A high pressure gas jet was used to simulate diesel injection conditions. The injection mass flow rate was similar to that of typical diesel injection. The experiments were performed in a high pressure vessel at typical ambient gas density of diesel engine during spray injection. The ambient gas density was varied from 25 to 30 kg/m₃ and three nozzle diameters, 0.2, 0.35 and 0.5 mm were used. Both free and wall-impinging jet configurations were investigated by combining Laser-Induced Fluorescence (LIF) and Particle Image Velocimetry (PIV) to obtain simultaneous planar measurements of concentration and velocity. Fuel concentration fields were used to define the edges of the jet and allow an accurate determination of the air entrainment rate both in free and wall-impinging configurations.

In 1990, Roy Douglas developed an analytical method to calculate the global air-to-fuel ratio of a two-stroke engine from exhaust gas emissions. While this method has considerable application to two-stroke engines, it does not permit the calculation of air-to-fuel ratios for oxygenated fuels. This study proposed modifications to the Roy Douglas method such that it can be applied to oxygenated fuels. The ISO #16183 standard, the modified Spindt method, and the Brettschneider method were used to evaluate the modifications to the Roy Douglas method. In addition, a trapped air-to-fuel ratio, appropriate for two-stroke engines, was also modified to incorporate oxygenated fuels. To validate the modified calculation method, tests were performed using a two-stroke carbureted and two-stroke direct injected marine outboard engine over a five-mode marine test cycle running indolene and low level blends of ethanol and iso-butanol fuels.

The study of spray-wall interaction is of great importance to understand the dynamics that occur during fuel impingement onto the chamber wall or piston surfaces in internal combustion engines. It is found that the maximum spreading length of an impinged droplet can provide a quantitative estimation of heat transfer and energy transformation for spray-wall interaction. Furthermore, it influences the air-fuel mixing and hydrocarbon and particle emissions at combusting conditions. In this paper, an analytical model of a single diesel droplet impinging on the wall with different inclined angles (α) is developed in terms of βm (dimensionless maximum spreading length, the ratio of maximum spreading length to initial droplet diameter) to understand the detailed impinging dynamic process.

The more and more severe regulations on exhaust emissions from vehicles and the worldwide demand for fuel consumption reduction impose continuous improvements of the engine thermal efficiency. Base engine geometrical setups are important aspects which have to be taken into account to improve the engine efficiency. This paper discusses the influence of the bore-to-stroke ratio on emissions, fuel consumption and full load performances of a Diesel engine. The expected advantage of a reduced bore-to-stroke ratio is mainly a decrease of the thermal losses, due to a higher volume-to-surface ratio, reducing the wall surfaces, responsible for the heat losses, per volume of gas. The advantages concerning the wall heat losses are opposed to the disadvantages of lower volumetric efficiency, as a smaller bore requires smaller valve diameter. Additionally does a reduction of the bore-to-stroke ratio lead to an increase of the friction losses, as the mean piston speed increases.

Legal constraints concerning CO2 emissions have made the improvement of light duty vehicle efficiency mandatory. In result, vehicle powertrain and its development have become increasingly complex, requiring the ability to assess rapidly the effect of several technological solutions, such as hybridization or internal combustion engine (or ICE) downsizing, on vehicle CO2 emissions. In this respect, simulation is nowadays a common way to estimate a vehicle's fuel consumption on a given driving cycle. This estimation can be done with the knowledge of vehicle main characteristics, its transmission ratio and efficiency and its internal combustion engine fuel consumption map. While vehicle and transmission parameters are relatively easy to know, the ICE consumption map has to be obtained through either test bench measurements or computation.

The 3-Zones Extended Coherent Flame Model (ECFM3Z) and the Tabulated Kinetics for Ignition (TKI) auto-ignition model are widely used for RANS simulations of reactive flows in Diesel engines. ECFM3Z accounts for the turbulent mixing between one zone that contains compressed air and EGR and another zone that contains evaporated fuel. These zones mix to form a reactive zone where combustion occurs. In this mixing zone TKI is applied to predict the auto-ignition event, including the ignition delay time and the heat release rate. Because it is tabulated, TKI can model complex fuels over a wide range of engine thermodynamic conditions. However, the ECFM3Z/TKI combustion modeling approach requires an efficient predictive spray injection calculation. In a Diesel direct injection engine, the turbulent mixing and spray atomization are mainly driven by the liquid/gas coupling phenomenon that occurs at moving liquid/gas interfaces.