bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermo-Fluid Analysis of the Exhaust Manifold Integrated With Cylinder Head
Authors: Neshan Mohammad Amin , Keshavarz Ali , Jazayeri Ali , Ghasemian Ali 
Published: July 2013

Exhaust manifold is an individual part of conventional internal combustion engines which is made of cast iron. Furthermore expensive alloys are needed to increase its thermal resistance. In the Integrated Exhaust Manifold into Cylinder Head (IEMCH), the exhaust manifold is manufactured as one part with the cylinder head. Thus its material changes from cast iron to aluminum which has a much lower thermal resistance than the cast iron. IEMCH has many advantages such as, low cost, lower weight and volume, less fuel consumption and faster warm-up. But due to its lower thermal resistance, it must be cooled.
Here a new exhaust manifold is designed for IEMCH. Thermo-fluid analysis is carried out numerically to evaluate temperature limitation of the new exhaust manifold. The obtained results are compared to the standard exhaust manifold which indicates that by means of cooling, the new exhaust manifold can be remained at its proper temperature limitation. Thus no expensive alloys are needed in the new exhaust manifold.
Effect of Injection Timing on Combustion, NOx, Particulate Matter and Soluble Organic Fraction Composition in a 2-Stroke Tier 0+ Locomotive Engine
Authors: Bohac Stanislav V. , Feiler Eric , Bradbury Ian 
Published: July 2013

This study investigates how injection timing affects combustion, NOx, PM mass and composition from a 2-stroke turbocharged locomotive diesel engine fitted with an early-development Tier 0+ emissions kit. The objective of the work is to gain insight into how injection timing affects combustion and emissions in this family of engines, modified to meet the newly implemented Tier 0+ emissions requirements, and to identify areas of potential future emissions reduction. For a range of injection timings at a medium load (notch 5) operating condition, the majority of PM mass is comprised of insolubles (81–89%), while the soluble component of PM (SOF) accounts for a smaller fraction (11–19%) of total PM mass. The SOF is 66–80% oil-like C22–C30+ hydrocarbons, with the remainder being fuel-like C9–C21 hydrocarbons.
A heat release analysis is used to elucidate how injection timing affects combustion by calculating mass fraction burn curves. It is observed that retarding injection timing retards combustion phasing, decreases peak cylinder pressure and temperature, and increases expansion pressure and temperature. Results show that insolubles and fuel-like hydrocarbons increase and oil-like hydrocarbons decrease with later injection timing. Analysis suggests that insolubles and fuel-like HC increase due to lower peak combustion temperature, while oil-like HC, which are distributed more widely throughout the cylinder, decrease due to higher expansion temperatures. The net result is that total PM mass increases with retarded combustion phasing, mostly due to increased insolubles.
Considering the high fraction of insoluble PM (81–89%) at all injection timings tested at notch 5, steps taken to reduce PM elemental carbon should be the most effective path for future reductions in PM emissions. Further reductions in oil consumption may also reduce PM, but to a smaller extent.
Fluid-Dynamic Characterization of a CNG Injection System
Authors: Baratta Mirko , Misul Daniela , Spessa Ezio , Gazzilli Giuseppe , Gerini Andrea 
Published: July 2013

A renewed interest in CNG fuelled engines, which has recently been boosted by the even more stringent emissions regulations, has generated considerable R&D activity in the last few years. In order to fulfill such limits, most current CNG vehicles combine advanced technical and control solutions such as VVA intake systems, new turbocharging solutions, enhanced ECU strategies, etc. The present work focuses on the complete fluid-dynamic characterization of a gaseous injection system so as to support the design of the related control module and devices. To that end, a numerical investigation into the fluid-dynamic behavior of a commercial CNG injection system has been extensively carried out by means of the GT-POWER code.
A detailed geometrical model including the rail, the injectors as well as the pipe connecting the pressure regulator to the rail has been built in the GT-POWER environment. The model has been validated by comparing the experimental to the numerical outputs for the rail pressure and for the injected mass quantity. The model has hence been applied to the prediction of the pressure waves produced by the injection event and of their effect on the actually injected fuel mass. Moreover, the influence of the pressure regulator dynamics has been assessed by simulating the impact on the system behavior of a pressure noise downstream from the regulator. Finally, the possibility of reducing the rail volume, thus enhancing its dynamic response, has been investigated.
The results have shown a good agreement between the predicted and the measured rail pressure and injected fuel mass flow rates over a wide range of engine operation conditions. Moreover, the dynamic simulations sketched a dependence of the injected fuel mass on the average rail pressure level, which in turn appeared to reduce for increasing engine power outputs. Finally, the reduction in the rail volume has proved not to significantly affect the injected mass flow rate.
An Experimental Study of Two-Stage Combustion Strategy on Combustion and Emission Characteristics in a Diesel Engine Fueled With Biodiesel Blends
Authors: Lee Donggon , Jeong Kyusoo , Roh Hyun Gu , Lee Chang Sik 
Published: July 2013

This study describes the effects of two-stage combustion (TSC) strategy on combustion and emission characteristics in 4 cylinder common-rail direct injection (CRDI) diesel engine fueled with biodiesel blends. In the present work, to investigate the combustion and emission characteristics, the experiments were performed under various injection pressures, first injection quantity and first injection timing of TSC strategy at constant engine speed and engine load. In addition, conventional diesel fuel (ULSD) was used to compare with biodiesel blends.
The experimental results show that combustion of biodiesel blends is stable for various test conditions regardless of blending ratio, and indicated specific fuel consumption (ISFC) was increased as biodiesel blending ratio increased. In the emission characteristics, biodiesel blends generated lower indicated specific nitrogen oxides (IS-NOx) and indicated specific soot (IS-Soot) emissions compared to those of ULSD when the first injection quantity increased.
Influence of Prechamber-Geometry and Operating-Parameters on Cycle-to-Cycle Variations in Lean Large-Bore Natural Gas Engines
Authors: Kammerstätter S. , Sattelmayer T. 
Published: July 2013

Lean large-bore natural gas engines are usually equipped with gas-scavenged prechambers. After ignition and during combustion in the prechamber hot reacting jets penetrate the main chamber and provide much higher ignition energies than electric spark plugs. Although prechambers stabilize combustion, limitations of the concept are observed at very lean main chamber mixtures and large cylinder diameters, which appear as cycle-to-cycle variations of heat release and pressure.
At the Thermodynamics Institute of the Technical University of Munich cycle-to-cycle variations are investigated in an unique periodically chargeable high pressure combustion cell with full optical access to the entire main chamber. Recently, the influence of the ignition timing, the amount of scavenge-gas of the prechamber and the cross section of the prechamber exit orifices on cycle-to-cycle variations have been studied. From the pressure traces characteristic parameters of the combustion process like the ignition probability, the ignition delay and the rate of the pressure rise have been derived. By analysing the emission of OH*-chemiluminescence in terms of reacting area and light emission and on the basis of numerical simulations information on the source of cycle-to-cycle variations is obtained. Finally it is shown that cycle-to-cycle variations can be reduced remarkably by appropriate selection and combination of prechamber geometry and operating parameters.
DI-CNG Injector Characterization at Small Energizing Times by Means of Numerical Simulation
Authors: Baratta Mirko , Catania Andrea E. , Rapetto Nicola , Fuerhapter Alois , Gerlich Matthias , Zoels Wolfgang 
Published: July 2013

In the last few years, a significant research effort has been made for developing and enhancing Direct Injection (DI) for compressed natural gas (CNG) engines. Several research projects have been promoted by the European Community (EC) in this field with the objective of finding new solutions for the automotive market and also of encouraging a fruitful knowledge exchange among car manufacturers, suppliers and technical universities.
This paper concerns part of the research activity that has been carried out by the Politecnico di Torino, AVL List GmbH and Siemens AG within the EC VII Framework Program (FP) InGAS Collaborative Project (CP), aimed at optimizing the control phase of a new injector for CNG direct injection, paying specific attention to its behavior at small injected-fuel amounts, i.e., small energizing times. The CNG injector which was developed within the research project proved to be suitable to be used in a DI SI engine, featuring a pent-roof combustion chamber head and a bowl in piston, with reference to both homogeneous and stratified charge formation. Fuel flow measurements made by AVL on the four-cylinder engine revealed a good linearity between injection duration and fuel mass-flow rate for injection durations above a reference value.
In order to improve the injector characterization at short injection durations, an experimental and numerical activity was designed. More specifically, a multidimensional CFD model of the actual injector geometry was built by Politecnico di Torino, and purposely-designed simulation cases were carried out, in which the needle-lift time-history was defined on the basis of experimental measurements made by Siemens. The numerical model was validated on the basis of experimental data concerning the total injected-fuel amount under different conditions. Then, the model was applied in order to evaluate the dynamic flow characteristic by taking also the inner geometry of the injector valve group into account, so as to establish a correlation to the needle lift measurements done by Siemens for injector characterization.
In the paper this dynamic behavior of the injector is analyzed, under actual operating conditions, and its impact on the nozzle injection capability is discussed. The simulation results did not show significant oscillations of the stagnation pressure upstream of the nozzle throat section, and thus the resultant mass-flow rate profile is almost proportional to the needle-lift one. As a consequence, in order to characterize the injector flow behavior in the nonlinear region (short injection duration), the measurement of needle lift is sufficient.
Effects of H2 Addition to CNG Blends on Cycle-to-Cycle and Cylinder-to-Cylinder Combustion Variation in an SI Engine
Authors: Baratta Mirko , d’Ambrosio Stefano , Misul Daniela , Spessa Ezio 
Published: July 2013

An experimental investigation and a burning-rate analysis have been performed on a production 1.4 liter CNG (compressed natural gas) engine fueled with methane-hydrogen blends. The engine features a pent-roof combustion chamber, four valves per cylinder and a centrally located spark plug.
The experimental tests have been carried out in order to quantify the cycle-to-cycle and the cylinder-to-cylinder combustion variation. Therefore, the engine has been equipped with four dedicated piezoelectric pressure transducers placed on each cylinder and located by the spark plug. At each test point, in-cylinder pressure, fuel consumption, induced air mass flow rate, pressure and temperature at different locations on the engine intake and exhaust systems as well as ‘engine-out’ pollutant emissions have been measured. The signals correlated to the engine operation have been acquired by means of a National Instruments PXI-DAQ system and a home developed software. The acquired data have then been processed through a combustion diagnostic tool resulting from the integration of an original multizone thermodynamic model with a CAD procedure for the evaluation of the burned-gas front geometry. The diagnostic tool allows the burning velocities to be computed.
The tests have been performed over a wide range of engine speeds, loads and relative air-fuel ratios (up to the lean operation). For stoichiometric operation, the addition of hydrogen to CNG has produced a bsfc reduction ranging between 2 to 7% and a bsTHC decrease up to the 40%. These benefits have appeared to be even higher for lean mixtures. Moreover, hydrogen has shown to significantly enhance the combustion process, thus leading to a sensibly lower cycle-to-cycle variability. As a matter of fact, hydrogen addition has generally resulted into extended operation up to RAFR = 1.8. Still, a discrepancy in the abovementioned conclusions was observed depending on the engine cylinder considered.
Development of a Post-Processing Methodology for Studying Thermal Stratification in an HCCI Engine
Authors: Lawler Benjamin , Hoffman Mark , Filipi Zoran , Güralp Orgun , Najt Paul 
Published: July 2013

Naturally occurring thermal stratification significantly impacts the characteristics of HCCI combustion. The in-cylinder gas temperature distributions prior to combustion dictate the ignition phasing, burn rates, combustion efficiency, and unburned hydrocarbon and CO emissions associated with HCCI operation. Characterizing the gas temperature fields in an HCCI engine and correlating them to HCCI burn rates is a prerequisite for developing strategies to expand the HCCI operating range.
To study the development of thermal stratification in more detail, a new analysis methodology for post-processing experimental HCCI engine data is proposed. This analysis tool uses the autoignition integral in the context of the mass fraction burned curve to infer information about the distribution of temperature that exists in the cylinder prior to combustion. An assumption is made about the shape of the charge temperature profiles of the unburned gas during compression and after combustion starts elsewhere in the cylinder. Secondly, it is assumed that chemical reaction rates proceed very rapidly in comparison to the staggering of ignition phasing from thermal stratification. The autoignition integral is then coupled to the mass fraction burned curve to produce temperature-mass distributions that are representative of a particular combustion event. Due to the computational efficiency associated with this zero-dimensional calculation, a large number of zones can be simulated at very little computational expense.
The temperature-mass distributions are then studied over a coolant temperature sweep. The results show that very small changes to compression heat transfer can shift the distribution of mass and temperature in the cylinder enough to significantly affect HCCI burn rates and emissions.
Fuzzy Logic Control of Diesel Combustion Phasing Using Ion Current Signal
Authors: Badawy Tamer , Khaled Nassim , Henein Naeim 
Published: July 2013

Diesel engines have to meet stringent emissions standards without penalties in performance and fuel economy. This necessitated the use of elaborate after treatment devices to reduce the tail pipe emissions. In order to decrease the demand on the after treatment devices, there is a need to reduce the emissions in the formation stage during combustion. This requires a precise control of the phasing of the combustion process. Currently, diesel engines are controlled by pre-set open loop schedules that require extensive, time consuming and costly laboratory tests and calibration tasks to meet the production target goals which are stricter than the emission standards. Such goals are set as a safe guard against the deterioration during engine life cycle. This paper presents an incremental fuzzy logic controller that adjusts the combustion phasing as per desired targets to meet production goals over the engine life period. An ion current/ glow plug sensor and its circuit are used to produce a signal indicative of different combustion parameters. Signal conditioning and filtering are applied to improve the quality of ion current.
The algorithm developed in this paper optimizes the ion current feed back to increase its reliability for stable engine control while maintaining fast controller response, and high accuracy. Experiments are carried out on a four cylinder, turbo-charged, 4.5L heavy duty diesel engine equipped with a common rail injection system and an open ECU. The response of the controller is evaluated from experimental data obtained by running the engine under different steady, and transient operating conditions. The results demonstrate the ability of the closed-loop control system in achieving the desired combustion phasing.
High Efficiency Two-Valve DI Diesel Engine for Off-Road Application Complying With Upcoming Emission Limits
Authors: Bianchi Gian Marco , Cazzoli Giulio , Forte Claudio , Costa Marco , Oliva Marcello 
Published: July 2013

Nowadays, environmental concerns are posing a great challenge to DI Diesel engines. Increasingly tightening emission limits require a higher attention on combustion efficiency. In this scenario, computational fluid-dynamics can prove its power guaranteeing a deeper understanding of mixture formation process and combustion. A high efficiency Diesel engine can be developed only mastering all the parameters that can affect the combustion and, therefore, NOx and soot emissions. In this work, the development of an engine in order to fulfill Tier 4i emission standard will be presented. Originally, the engine was a two-valve engine supplied with a DPF. Since no SCR aftertreatment is supplied, NOx emission target are achieved through external exhaust gas recirculation and retarding the start of injection. In order to fulfill Tier 4i emissions, the main concern is on soot emission and, thus, the combustion chamber has been re-designed, through CFD simulations, leading to a better interaction between the flow field, the fuel spray and the piston bowl geometry.
Particularly, through intake phase simulations, performed with the CFD code Fire v2009 v3, different intake ducts, with different swirl ratio, have been simulated in order to provide a flow field as realistic as possible for the combustion simulations. Through combustion process simulations, performed with the CFD code Kiva, by varying different parameters the interaction between the swirl flow field, generated by the intake duct, the reverse squish motion, and motions aerodynamically generated by spray has been investigated leading to the definition of a new engine lay-out. The study shows how, given the need of retarded injection for limiting NOx emission, the decrease of swirl ratio, when combined with a proper piston bowl design, allows a significant decrease of soot emissions and the achievement of Tier 4i emission standard.
Accelerometer Signal to Characterize the Combustion Development in Multiple Injection Diesel Engine
Authors: Chiatti G. , Chiavola O. , Recco E. 
Published: July 2013

This work constitutes one of the last steps of a comprehensive research program in which vibration sensors are used with the purpose of developing and setting up a methodology that is able to perform a real time control of the combustion process by means of non-intrusive measurements.
Previous obtained and published results have demonstrated that a direct relationship exists between in-cylinder pressure and engine block vibration signals. The analysis of the processed data have highlighted that the block vibration signal may be used to locate, in the crank–angle domain, the combustion phases (the start of the combustion, the crank angle value corresponding to the beginning of main combustion and to the in-cylinder pressure maximum value) and to quantify the in-cylinder pressure development by evaluating the pressure peak value and the pressure rise rate caused by the combustion process.
The aim of this work is to extend and validate the developed methodology when a multiple-injection strategy is imposed on the engine.
The paper presents the results obtained during the experimentation of a two cylinder diesel engine equipped with a common rail injection system, that was performed in the Laboratory of the Mechanical and Industrial Department of ‘ROMA TRE’ University. During the tests, a wide variation of the injection parameters settings is imposed on the engine (timing and duration) in its complete operative field.
Dilution Effects on Partially-Premixed Combustion of an Ultra-Low Sulphur Diesel Fuel Under Low-Load Operation
Authors: Dumitrescu Cosmin E. , Neill W. Stuart , Guo Hongsheng , Chippior Wallace L. 
Published: July 2013

Dilution of partially-premixed combustion (PPC) using different combinations of excess air (λ>1) and exhaust gas recirculation (EGR) was investigated in a single-cylinder, heavy-duty diesel engine equipped with common-rail fuel injection. The experiments were limited to a single fuel injection event using ultra-low sulphur diesel fuel at a low engine load (∼3 bar BMEP) and engine speeds of 900 and 1350 rpm. The start of injection was varied to optimize the combustion performance and emissions.
The experimental results show that increasing air dilution at constant EGR reduced BSFC slightly. CO and HC emissions decreased significantly due to the increased oxygen concentration, but NOx and soot emissions increased. For a given level of charge dilution, there was an optimal EGR rate to minimize BSFC. NOx emissions decreased significantly as the proportion of dilution by EGR was increased, but CO and HC emissions increased due to the reduced in-cylinder temperature and oxygen concentration, which increased the combustion duration.
The Application of the Time Series Theory to Processing Data From the SBAS Receiver in Safety Mode
Authors: Jonas M. 
Published: July 2013

Before satellite-based augmentation systems (SBAS) such as the Wide Area Augmentation System (WAAS) in the USA, and the European Geostationary Navigation Overlay Service (EGNOS), will be used in railway safety-related applications, it is necessary to determine reliability attributes of these systems as quality measures from the user’s point of view. It is necessary to find new methods of processing data from the SBAS system in accordance with strict railway standards.
For this purposes data from the SBAS receiver with the Safety of Life Service was processed by means of the time series theory. At first, a basic statistic exploration analysis by means of histograms and boxplot graphs was done. Then correlation analysis by autocorrelation (ACF), and partial autocorrelation functions (PACF), was done. Statistical tests for the confirmation of non-stationarity, and conditional heteroscedasticity of time series were done. Engle’s ARCH test confirmed that conditional heteroscedasticity is contained. ARMA/GARCH models were constructed, and their residuals were analyzed.
Autocorrelation functions and statistical tests of models residuals were done. The analysis implies that the models well cover the variance volatility of investigated time series and so it is possible to use the ARMA/GARCH models for the modeling of SBAS receiver outputs.