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Viewing 1 to 30 of 5641
Technical Paper
2014-09-15
Kai Chen
The synthetic paraffinic kerosine (SPK) produced via HEFAs is of great interest for civil aviation industry as it exhibits an excellent thermal oxidative stability with significantly lower particulate matter emission. However, due to its aromatic free characteristics, the widespread use of SPK is limited by its compatibility with non-metal materials such as fuel tank elastomers. In this research the compatibility of SPK and its blends with widely used aircraft fuel tank elastomers were systematically studied. Experimental results demonstrated the volume swellability of all selected materials showed a linear relationship with volume percentage of No.3 jet fuel in SPK blend. The increase of volume percentage of No.3 jet fuel in the SPK blend increased volume swellability for all materials except fluorosilicone gasket. The alkyl benzenes and naphthalenes in the blend acted as the hydrogen donors, which facilitated the formation of polymer matrix and led to the increase of the distance between polymer chains.
Technical Paper
2014-04-01
Dhaval Vaishnav, Mike Dong, Mayur Shah, Francisco Gomez, Mohammad Usman
When a vehicle with a partially filled fuel tank undergoes sudden acceleration, braking, turning or pitching motion, fuel sloshing is experienced. It is important to establish a CAE methodology to accurately predict slosh phenomenon. Fuel slosh can lead to many failure modes such as noise, erroneous fuel indication, irregular fuel supply at low fuel level and durability issues caused by high impact forces on tank surface and internal parts. This paper summarizes activities carried out by the fuel system team at Ford Motor Company to develop and validate such CAE methodology. In particular two methods are discussed here. The first method is Volume Of Fluid (VOF) based incompressible multiphase Eulerian transient CAE method. The CFD solvers used here are Star CD and Star CCM+. The second method incorporates Fluid-Structure interaction (FSI) using Arbitrary Lagrangian-Eulerian (ALE) formulation. While Eulerian domain predicts motion and forces of fluid inside the tank, Lagrangian domain models tank shell and predicts its vibration under these forces.
Technical Paper
2014-04-01
Praveensingh Jadhav, Aditya Nanda, Manas Tripathi, Amit Kumar, Shriganesh Umbarkar
Abstract Global automobile market is very sensitive to vehicle fuel economy. Gross vehicle weight has substantial effects on FE. Hence, for designers it becomes utmost important to work on the weight reduction ideas up to single component level. Fuel delivery pipe (Fuel Rail) is one such component where there is a big potential. Fuel rail is an integral part of the vehicle fuel system and is mounted on the engine. Primarily it serves as a channel of fuel supply from fuel tank through fuel lines to the multiple fuel injectors, which further sprays the fuel into intake ports at high pressure. Due to opening and closing of injectors, pulsations are generated in fuel lines, so fuel rail also acts as a surge tank as well as a pulsation damper. All these factors make the design of a fuel rail very critical and unique for a particular engine. Materials like aluminum, plastic and sheet metal are generally used for fuel rail manufacturing. In this technical paper, design considerations for plastic fuel rail are explained.
Technical Paper
2014-04-01
Barry (Baizhong) Lin, Mike Gundle, Mike Rowley, Alan Aloe, Frederick Zweng, Eric Blackburn, Chandra Thandhayuthapani, Chandra Thonta, Edward Law, Kah Wah Long, Mike Temkin, Zachary Calkins
Abstract Fuel Tank Straps very often get different durability fatigue test results from different types of durability testing such as shaker table vibration, road test simulator (RTS) vehicle testing and proving ground vehicle durability testing. One test produces good durability results and other may indicate some durability risk. A special study was conducted to address this inconsistency. It was found that fuel level in the tank plays a big role in fuel tank strap durability. Higher fuel levels in a tank produce higher loads in straps and lower fatigue life. This paper will use a CAE fuel tank strap model and acquired proving ground strap load data to study fuel level influence in fuel tank strap durability. The fuel level study includes a full tank of fuel, 3 quarters tank of fuel, a half tank of fuel and one quarter tank of fuel. Based on CAE results of one 32 gallon fuel tank it is observed that fuel tank strap fatigue life improves by one order of magnitude or 10 times for every quarter tank of fuel level reduction.
Technical Paper
2014-04-01
V. Jadon, G. Agawane, A. Baghel, Venkatesham Balide, R. Banerjee, A. Getta, H. Viswanathan, A. Awasthi
Abstract With significant decrease in the background noise in present day automobiles, liquid slosh noise from an automotive fuel tank is considered as a major irritant during acceleration and deceleration. All major international OEMs and their suppliers try to reduce sloshing noise by various design modifications in the fuel tank. However, most major activities reported in open literature are primarily based on performing various CAE and experimental studies in isolation. However, noise generation and its propagation is a multiphysics phenomenon, where fluid mechanics due to liquid sloshing affects structural behaviour of the fuel tank and its mountings which in turn affects noise generation and propagation. In the present study a multiphysics approach to noise generation has been used to predict liquid sloshing noise from a rectangular tank. Computational Fluid dynamics (CFD), Finite Element Analysis (FEA) and Boundary Element Method (BEM) simulation studies have been performed in a semi-coupled manner to predict noise.
Technical Paper
2014-04-01
MIng Huo, Mianzhi Wang, Chia-Fon Lee
Abstract In the new combustion strategies such as RCCI and dual-fuel combustion, the diesel pilot injection plays a pivotal role as it determines the ignition characteristics of the mixture and ultimately the combustion and emission performance. In this regard, equivalence ratio distribution resulted from the pilot injection becomes very important. In this work, computation study is carried out using KIVA-3V to simulate the engine compression stroke from intake valve close (IVC) to close to TDC so as to investigate the impact of piston geometry, injection start timing and flow initialization on the equivalence ratio distribution from a pilot injection in HSDI engine. Two piston geometry (the stock piston with bowl-in piston shape and a flat piston), three injection timing (80 CA, 60 CA and 40 CA BTDC) and three velocity initializations (Bessel fit with constant value of 3.11 and 2.2; and a velocity field obtained from PIV measurement on a steady-state bench flow test facility with minimum valve lift) were considered.
Technical Paper
2014-04-01
Raouf Mobasheri, Seyed Alireza Khabbaz
Abstract Exhaust Gas Recirculation (EGR) is an effective pre-treatment technique, which has been widely used to decrease the amount of the oxides of nitrogen (NOx) emission from diesel engines. However, the use of high EGR rates leads to the reduction in oxygen availability in the burning regions of the combustion chamber which impairs the soot oxidation process. Consequently, higher soot generated by EGR leads to long-term usage problems inside the engines such as higher carbon deposits, lubricating oil degradation and enhanced engine wear. In this study, CFD modeling has been carried out to analyze the effects of high EGR rates in conjunction with optimum multiple injection strategies. A heavy-duty DI Diesel engine has been modeled to study the engine performance and emissions with various EGR rates (from 0% to 40%). The selected operating points have been achieved with the same injection profile including a main and post injection for all considered cases. The results showed the effectiveness of multiple injections at controlling soot emission under high EGR conditions.
Technical Paper
2014-04-01
Remko Baur, Jan Peter Blath, Christian Bohn, Franz Kallage, Matthias Schultalbers
Abstract The precision of direct fuel injection systems of combustion engines is crucial for the further reduction of emissions and fuel consumption. It is influenced by the dynamic behavior of the fuel system, in particular the injection valves and the common rail pressure. As model based control strategies for the fuel system could substantially improve the dynamic behavior, an accurate model of the common rail injection system for gasoline engines - consisting of the main components high-pressure pump, common rail and injection valves - that could be used for control design is highly desirable. Approaches for developing such a model are presented in this paper. For each key component, two models are derived, which differ in temporal resolution and number of degrees of freedom. Experimental data is used to validate and compare the models. The data was generated on a test bench specifically designed and built for this purpose. The test bench consists of the relevant components of a current production four-cylinder gasoline engine which were slightly modified in order to mount sensors.
Technical Paper
2014-04-01
Benedikt Huber, Heinz Ulbrich
Abstract Common rail diesel injectors are multi-domain systems with complex interactions between mechanical, hydraulic and electrical components. For a detailed understanding of the dynamic behavior and for further performance improvements, often simulation models are indispensable. Injection dynamics is influenced by the opening and closing dynamics of the solenoid valve. Therefore an accurate simulation model of the solenoid valve is necessary for injector simulations. The objective of this study is to present a validated simulation model of the solenoid valve of a commercially available common rail diesel injector. For modeling the solenoid valve, a division into a mechanical and a magnetic submodel is done. The mechanical submodel is made up by a two mass system representing the pin and the armature of the solenoid valve. Contacts are modeled using linear-elastic spring-damper elements and viscous damping is considered for friction representation. The magnetic submodel is based on experimentally gained static magnetic force data.
Technical Paper
2014-04-01
Subrata Sarkar, Kailash Golecha, Surbhi Kohli, Vaughn Mills, Mustafa Huseyin, Pritam Bhurke, Stefan Walter, Ravikumar S. Dinni, Shrikrishna Jaywant Deshpande
Abstract The primary objective of this study was to provide an efficient system solution for the removal of fuel from an Active Drain Liquid Trap (ADLT), used in automotive vent systems; using a Jet Pump. The Voice of Customer was collected and analyzed. The two major focus areas identified were - improvement in robustness of Jet Pump performance and maximization of induced flow. Robust design of such a Jet Pump was carried out using Taguchi's Orthogonal Crossed Array based parameter design, through computer simulation. Two Jet Pumps were designed for Gasoline based vehicles; one with the conventional approach and the other with the robust design approach. Both were put on a field trial, integral with the vent system. The robust design showed a tremendous improvement in performance over the conventional design, due to the elimination of cavitation and insensitivity to noises.
Technical Paper
2014-04-01
Karthik Nithyanandan, Han Wu, Ming Huo, Chia-Fon Lee
Abstract Alcohols, because of their potential to be produced from renewable sources and their characteristics suitable for clean combustion, are considered potential fuels which can be blended with fossil-based gasoline for use in internal combustion engines. As such, n-butanol has received a lot of attention in this regard and has shown to be a possible alternative to pure gasoline. The main issue preventing butanol's use in modern engines is its relatively high cost of production. Acetone-Butanol-Ethanol (ABE) fermentation is one of the major methods to produce bio-butanol. The goal of this study is to investigate the combustion characteristics of the intermediate product in butanol production, namely ABE, and hence evaluate its potential as an alternative fuel. Acetone, n-butanol and ethanol were blended in a 3:6:1 volume ratio and then splash blended with pure ethanol-free gasoline with volumetric ratios of 0%, 20%, 40% to create various fuel blends. These blends were tested in a port-fuel injected spark-ignited (SI) engine and their performance was evaluated through measurements of in-cylinder pressure, and various exhaust emissions.
Technical Paper
2014-04-01
Eric Hein, Adam Kotrba, Tobias Inclan, Andrew Bright
Secondary fuel injection is applied to facilitate active soot management of the particulate filter within diesel aftertreatment systems, avoiding concerns with fuel delivery via in-cylinder post-injection. System performance is dependent on the thermo-fluid interactions of the injected fuel with the exhaust stream, with the intent of having more fully vaporized fuel and a well-mixed air-fuel mixture at the inlet of the oxidation catalyst for uniform thermal distribution as it exothermically reacts. Pre-heating the fuel with a diesel vaporizer prior to its delivery into the exhaust enables improved system performance, reducing droplet sizes and mixing demands. A diesel vaporizer is applied within the exhaust of a medium duty truck application, and the response of the catalyst is characterized across a variety of conditions. Cross-sectional measurements at the catalyst and filter outlet are described, including gas velocity, temperature, and HC concentration, and the effect of poor fuel vaporization is demonstrated.
Technical Paper
2014-04-01
Tamer Badawy, Naeim Henein
Abstract Advanced injection systems play a major role in reducing engine out emission in modern diesel engines. One interesting technology is the common rail injection system which is becoming more vital in controlling emission due to its flexibility in injection pressure, timing and number of injection events. Many studies have showed the advantages of using such injection parameters to meet the strict emission and improve engine performance. A glow plug/ ion current sensor was used to measure ionization produced during the combustion process. The ion current signal contains many valuable information including combustion phasing, duration and combustion resonance. In prior publications, it was demonstrated the capability of the ion current to control the combustion phasing and the ability to detect combustion resonance. Therefore, the experimental testing was conducted under controlled combustion phasing using the feedback from the ion current sensor. Since the combustion noise is mainly produced by combustion resonance, the ion current sensor was used to detect combustion resonance in this work.
Technical Paper
2014-04-01
Robert C. Elgin, Shane Daly, Christopher L. Hagen
In this paper we describe the experimental apparatus used to validate concepts associated with a bimodal internal combustion engine for use in natural gas vehicles (NGV's). In one mode, all engine cylinders fire normally providing locomotion for the NGV. In the other mode, one cylinder of the engine is used to compress residential natural gas, in multiple stages, to a standard US compressed natural gas (CNG) vehicle storage tank pressure of 250 bar. In the refueling mode, while the single cylinder is compressing natural gas it is powered by natural gas combustion in the remaining engine cylinders. Here we describe the engine dynamometer testing used to validate the bimodal engine design described in a companion paper. More specifically, a base compression ignition engine is powered by an AC motor while pumping air into storage tanks while all relevant thermodynamic parameters are recorded. The experimental data is compared with numerical model data in anticipation of convergence between the two.
Technical Paper
2014-04-01
Zhijia Yang, Richard Stobart, Edward Winward, Thomas Steffen
Abstract A three-pulse fuel injection mode has been studied by implementing two-input-two-output (2I2O) control of both peak combustion pressure (Pmax) and indicated mean effective pressure (IMEP). The engine test results show that at low engine speed, the first main injection duration and the second main injection duration are able to be used to control Pmax and IMEP respectively. This control is exercised within a limited but promising area of the engine map. However, at high engine speed, Pmax and IMEP are strongly coupled together and then can not be separately controlled by the two control variables: the first and the second main injection duration. A simple zero-dimensional (0D) combustion model together with correlation analysis method was used to find out why the coupling strength of Pmax and IMEP increases with engine speed increased. It was found that the closer coupling of Pmax and IMEP at higher engine speeds is due to the following reasons: (i) combustion occupied a larger crank angle; (ii) there was lower maximum heat release rate and (iii) there was a stronger correlation between IMEP and manifold air pressure (MAP) and promoted by the turbocharger.
Technical Paper
2014-04-01
Roberto Krenus, Marcos R. V. Passos, Thiago Ortega, Kenneth Mowery, Young Jin Kim, Lucille G. Lavan, Kuho Lee, C.J. Park, Kwang Han
Abstract After the second worldwide oil crisis, Brazil put in place by 1975 a strategic plan to stimulate the usage of ethanol (from sugar cane), to be mixed to the gasoline or to be sold as 100% ethanol fuel (known as E100). To enable an engine to operate with both gasoline and ethanol (and their mixtures), by 2003 the “Flex Fuel” technology was implemented. By 2012 calendar year, from a total of about 3.8 million vehicles sold in the Brazilian market, 91% offered the “Flex Fuel” technology, and great majority used a gasoline sub-tank to assist on cold starts (typically below 15°C, where more than 85% of ethanol is present in fuel tank). The gasoline sub-tank system suffers from issues such as gasoline deterioration, crash-worthiness and user inconvenience such as bad drivability during engine warm up phase. This paper presents fuel injector technologies capable of rapidly electrically heating the ethanol fuel for the Brazilian transportation market. These heated fuel injectors can be used for cold starting ethanol fueled engines as presented in SAE paper 2009-01-0615 [1] and to enable emissions reduction with a variety of automotive fuels as presented in SAE paper 2010-01-1265 [2].
Technical Paper
2014-04-01
Nicholas P. Echter, Kristina M. Weyer, Christopher W. Turner, Guy R. Babbitt, Christopher L. Hagen
Home refueling systems for natural gas vehicles are commercially available but suffer from long refilling times and high system costs. A novel concept of selectively repurposing one cylinder of a compressed natural gas (CNG) engine to be used as a compressor would allow a CNG vehicle to refuel itself quickly and with low capital cost. Using funding from the DOE through the ARPA-E program, such a vehicle is being designed and built by Oregon State University with the help of Czero, Inc. This paper outlines some of the early design, analysis and simulation work done to prove the concept and arrive at a first prototype design. Some of the unique challenges associated with the concept are discussed and the solutions to them are presented. An accompanying paper will present test results for the system.
Technical Paper
2014-04-01
Saiful Bari, Idris Saad
Abstract The performance of a compression ignition (CI) engine run with alternative fuel is inferior to when it is run with petro-diesel resulting in lower power, higher fuel consumption and higher carbon deposits. This is due to the poorer properties of the alternative fuel for the CI engine compared to petro-diesel, for instance, higher viscosity. Due to this factor, this research has grouped these fuels as higher viscous fuels (HVFs). In order to solve or reduce the problem of higher viscosity, this paper presents research that has sought to improve the in-cylinder airflow characteristics by using a guide vane so that the evaporation, diffusion, mixing and combustion processes can be stimulated eventually improving or at least reducing the problem. The in-cylinder airflow was studied using ANSYS-CFX with the help of SolidWorks. Firstly, the validated base model replicated from the generator of a CI engine was prepared. Then, 10 guide vane models with various numbers of vanes were adapted to simulate the in-cylinder airflow characteristics.
Technical Paper
2014-04-01
Daniela Anna Misul, Mirko Baratta, Hamed Kheshtinejad
Abstract Sustainable mobility has become a major issue for internal combustion engines and has led to increasing research efforts in the field of alternative fuels, such as bio-fuel, CNG and hydrogen addition, as well as into engine design and control optimization. To that end, a thorough control of the air-to-fuel ratio appears to be mandatory in SI engine in order to meet the even more stringent thresholds set by the current regulations. The accuracy of the air/fuel mixture highly depends on the injection system dynamic behavior and to its coupling to the engine fluid-dynamic. Thus, a sound investigation into the mixing process can only be achieved provided that a proper analysis of the injection rail and of the injectors is carried out. The present paper carries out a numerical investigation into the fluid dynamic behavior of a commercial CNG injection system by means of a 0D-1D code. The model has been validated by comparing the experimental readings to the numerical outputs in terms of injection system pressure profiles versus time.
Technical Paper
2014-04-01
Roy Hartfield, Timothy W. Ledlow
Abstract This paper describes the conception, development, and analysis of a new engine type. The continuous flow rotary vane engine described in this work represents a new paradigm in heat engine technology in that positive displacement compression and expansion processes are incorporated in a steady flow, continuous pressure gain combustion design. This concept is explored through an ideal gas cycle analysis and a more realistic engineering analysis in which the gas losses are accounted for using a zero dimensional energy based analysis and the friction losses are accounted for using a one-dimensional analysis. Realistic performance estimates are included. An ongoing prototype development effort to test the performance predictions is included and as assessment of applicability for the engine concludes the paper.
Technical Paper
2014-04-01
Bo Yang, Xing Wei, Ke Zeng, Ming-Chia Lai
Abstract Natural gas has been considered to be one of the most promising alternative fuels due to its lower NOx and soot emissions, less carbon footprint as well as attractive price. Furthermore, higher octane number makes it suitable for high compression ratio application compared with other gaseous fuels. For better economical and lower emissions, a turbocharged, four strokes, direct injection, high pressure common rail diesel engine has been converted into a diesel/natural gas dual-fuel engine. For dual-fuel engine operation, natural gas as the main fuel is sequentially injected into intake manifold, and a very small amount of diesel is directly injected into cylinder as the ignition source. In this paper, a dual-fuel electronic control unit (ECU) based on the PowerPC 32-bit microprocessor was developed. It cooperates with the original diesel ECU to control the fuel injection of the diesel/natural gas dual-fuel engine. Also, a real-time diesel substitution rate control strategy for the dual-fuel engine was implemented.
Technical Paper
2014-04-01
James F. Burkhard
Abstract This paper discusses on-engine results achieved in applying an algorithm-based Individual Cylinder Fuel Control (ICFC) to turbocharged four-cylinder engines. ICFC is a software algorithm which permits the detection and closed-loop correction of air/fuel imbalances on a cylinder-by-cylinder basis, which is not possible with typical bank-wide closed loop fuel control systems. Cylinder-to-cylinder air/fuel imbalances can be the result of a number of combined sources. The potential sources include fuel injector variation (both new and aged) as well as maldistribution of fresh air airflow, evaporative emissions purge flow, or exhaust gas recirculation flow. The ICFC algorithm requires no additional hardware beyond the typical sensor set already present on modern automotive spark-ignition engines, including oxygen sensor(s) and engine controller. While the ICFC algorithm has been employed in production programs since 2009, to date these have all been naturally-aspirated engines using switching oxygen sensors.
Technical Paper
2014-04-01
Donald Selmanaj, Harald Waschl, Michael Schinnerl, Sergio Savaresi, Luigi del Re
Abstract Especially in view of more and more stringent emission legislation in passenger cars it is required to reduce the amount of pollutants. In the case of Diesel engines mainly NOx and PM are emitted during engine operation. The main influence factors for these pollutants are the in-cylinder oxygen concentration and the injected fuel amount. Typically the engine control task can be divided into two separate main parts, the fuel and the air system. Commonly air system control, consisting of a turbocharger and exhaust gas recirculation control, is used to provide the required amount of oxygen and address the emission targets, whereas the fuel is used to provide the desired torque. Especially in transient maneuvers the different time scales of both systems can lead to emission peaks which are not desired. Against this background in this work instead of the common way to address the air system, the fuel system is considered to reduce emission peaks during transients. The idea is to start from a base calibration and adapt the injection parameters, like start and amount of pilot and main injection, to reduce transient emission peaks.
Technical Paper
2014-04-01
Rickard Solsjo, Mehdi Jangi, Clément Chartier, Oivind Andersson, Xue-Song Bai
Abstract The paper presents a large eddy simulation investigation on the effect of fuel injection pressure on mixing, in an optical heavy-duty diesel engine. Recent investigation on impinging wall jets at constant-volume and quiescent conditions exhibited augmented air entrainment in wall jets with increasing injection pressure, when compared with a free jet. The increased mixing rates were explained as owing to enhanced turbulence and vortex formation in the jet-tip in the recirculation zone. A recent investigation carried out in an optical heavy-duty diesel engine indicated however a negligible effect of injection pressure on the mixing in the engine environment. The effect of enhanced turbulence and vortex formation of the jet-tip in the recirculation zone is believed weaker than the effect of engine confinement, due to the presence of fuel from adjacent jets limiting the mixing the fuel with the ambient gas. The aims of this paper are to investigate this issue and to look into more details about the nature of the mixing process in diesel engines.
Technical Paper
2014-04-01
Yoshihiro Sukegawa, Kengo Kumano, Kenichiro Ogata
Abstract A technique of estimating particulate matter (PM) from gasoline direct injection engines is proposed that is used to compute mass density and particle number density of PM by using fuel mass in rich mixtures obtained by using non-combustion computational fluid dynamics (CFD). The CFD code that was developed by the authors employed a Cartesian coordinates system as a discretization method and large eddy simulation (LES) as a turbulence model. Fuel spray droplets were treated with the discrete droplet model (DDM). The code was verified with some experimental data such as those obtained from in-cylinder gas-flows with a laser Doppler velocimeter (LDV) and in-cylinder fuel concentration with laser induced fluorescence (LIF). PM emissions from a single-cylinder gasoline direct injection engine were measured with an electrical low pressure impactor (ELPI) to determine the model constants that were required in the estimation model. We confirmed that the technique could be applied to various engine operating conditions and fuel spray patterns.
Technical Paper
2014-04-01
Ireneusz Pielecha, Przemyslaw Borowski, Wojciech Cieslik
Abstract The current paper is a continuation of research on fuel atomization presented in SAE 2012-01-1662. The influence of varied position of the injector inside the combustion chamber on combustion, toxic compounds formation and exhaust emission were investigated. The simulation research (injection and combustion with NO formation) was supported with the model using the FIRE 2010 software by AVL. Modelling studies of toxic compounds formation were compared with the results of measurements on single-cylinder AVL 5804 engine. There thermodynamic evaluation indicators and exhaust emission were made.
Technical Paper
2014-04-01
Jian Huang, Zhi Wang, Martin Wissink, Rolf Reitz
Abstract The effects of the temporal and spatial distributions of ignition timings of combustion zones on combustion noise in a Direct Injection Compression Ignition (DICI) engine were studied using experimental tests and numerical simulations. The experiments were performed with different fuel injection strategies on a heavy-duty diesel engine. Cylinder pressure was measured with the sampling intervals of 0.1°CA in order to resolve noise components. The simulations were performed using the KIVA-3V code with detailed chemistry to analyze the in-cylinder ignition and combustion processes. The experimental results show that optimal sequential ignition and spatial distribution of combustion zones can be realized by adopting a two-stage injection strategy in which the proportion of the pilot injection fuel and the timings of the injections can be used to control the combustion process, thus resulting in simultaneously higher thermal efficiency and lower noise emissions. Simulated results show that if a large amount of the combustion occurs near the liner walls of the combustion chamber, this significantly contributes to high amplitude pressure oscillations, which leads to heavy knock and low thermal efficiency.
Technical Paper
2014-04-01
Nicholas Matthias, Thomas Wallner, Riccardo Scarcelli
The pressing need to improve U.S. energy independence and reduce climate forcing fossil fuel emissions continues to motivate the development of high-efficiency internal combustion engines. A recent trend has been to downsize and turbocharge automotive spark-ignited engines coupled with direct fuel injection to improve engine efficiency while maintaining vehicle performance. In-line with recent trends in state-of-the-art engine technology, the focus of this study is lean and EGR dilute combustion in a gasoline direct injection (GDI) engine. The lean and dilute operating limits are defined by combustion stability typically in terms of COVIMEP so experiments were carried out on an automotive size single-cylinder research engine to characterize combustion stability. From a 20,000 cycle sequence analysis, lean operating conditions exhibit binary high- to low-IMEP cycle sequences. This may be because the cycle-to-cycle feedback mechanisms are physically limited to one or two cycles. Longer sequences are observed with EGR likely because the EGR loop introduces a much longer transient feedback mechanism.
Technical Paper
2014-04-01
Bishwadipa Das Adhikary, Rolf Reitz, Stephen Ciatti, Christopher Kolodziej
Abstract The use of gasoline in a compression ignition engine has been a research focus lately due to the ability of gasoline to provide more premixing, resulting in controlled emissions of the nitrogen oxides [NOx] and particulate matter. The present study assesses the reactivity of 93 RON [87AKI] gasoline in a GM 1.9L 4-cylinder diesel engine, to extend the low load limit. A single injection strategy was used in available experiments where the injection timing was varied from −42 to −9 deg ATDC, with a step-size of 3 deg. The minimum fueling level was defined in the experiments such that the coefficient of variance [COV] of indicated mean effective pressure [IMEP] was less than 3%. The study revealed that injection at −27 deg ATDC allowed a minimum load of 2 bar BMEP. Also, advancement in the start of injection [SOI] timing in the experiments caused an earlier CA50, which became retarded with further advancement in SOI timing. To help explain these behaviors, simulations were carried out using the KIVA3V CFD code coupled with a Jacobian chemistry solver, SpeedChem.
Technical Paper
2014-04-01
Quan Liu, Alasdair Cairns, Hua Zhao, Mohammadreza Anbari Attar, Luke Cruff, Hugh Blaxill
Abstract The work was concerned with visualisation of the charge homogeneity and cyclic variations within the planar fuel field near the spark plug in an optical spark ignition engine fitted with an outwardly opening central direct fuel injector. Specifically, the project examined the effects of fuel type and injection settings, with the overall view to understanding some of the key mechanisms previously identified as leading to particulate formation in such engines. The three fuels studied included a baseline iso-octane, which was directly compared to two gasoline fuels containing 10% and 85% volume of ethanol respectively. The engine was a bespoke single cylinder with Bowditch style optical access through a flat piston crown. Charge stratification was studied over a wide spectrum of injection timings using the Planar Laser Induced Fluorescence (PLIF) technique, with additional variation in charge temperature due to injection also estimated when viable using a two-line PLIF approach. Overall, both gasoline-ethanol fuels generally exhibited a higher degree of stratification, albeit at least partly alleviated with elevated rail pressures.
Viewing 1 to 30 of 5641