Browse Topic: Gasoline

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Devices Providing Backfire Flame Control for Gasoline Engines in Marine ApplicationsJ1928_202511 (Current)11/21/2025
This SAE Standard covers the minimum requirements for design, construction, and testing of devices to prevent the propagation of backfire flame from within the gasoline engine to the surrounding atmosphere.
Marine Technical Steering Committee
1D Numerical and Experimental Investigations of an Ultralean Pre-Chamber Engine03-13-02-001211/19/2019
Abstract In recent years, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigations. With this solution, in fact, it is possible to simultaneously reduce NOx raw emissions and fuel consumption due to decreased heat losses, higher thermodynamic efficiency, and enhanced knock resistance. However, the real applicability of this technique is strongly limited by the increase in cyclic variation and the occurrence of misfire, which are typical for the combustion of homogeneous lean air/fuel mixtures. The employment of a Pre-Chamber (PC), in which the combustion begins before proceeding in the main combustion chamber, has already shown the capability of significantly extending the lean-burn limit. In this work, the potential of an ultralean PC SI engine for a decisive improvement of the thermal efficiency is presented by means of numerical and experimental analyses. The SI engine is experimentally investigated with and without the employment of the PC with the aim to analyze the real gain of this innovative combustion system. For both configurations, the engine is tested at various speeds, loads, and air-fuel ratios. A commercial gasoline fuel is directly injected into the Main Chamber (MC), while the PC is fed in a passive or active mode. Compressed Natural Gas (CNG) or Hydrogen (H2) is used in the actual case. A 1D model of the engine under study is implemented in a commercial modeling framework and is integrated with “in-house developed” sub-models for the simulation of the combustion and turbulence phenomena occurring in this unconventional engine. The numerical approach proves to reproduce the experimental data with good accuracy, without requiring any case-dependent tuning of the model constants. Both the numerical and experimental results show an improvement of the indicated thermal efficiency of the active PC, compared to the conventional ignition device, especially at high loads and low speeds. The injection of H2 into the PC leads to a significant benefit only with very lean mixtures. With the passive fueling of the PC, the lean-burn limit is less extended, with the consequent lower improvement potential for thermal efficiency.
Bozza, Fabio, De Bellis, Vincenzo, Tufano, Daniela, Malfi, Enrica, Müller, Christoph, Habermann, Knut
C919 Trailing Edge Assembly Interchangeable Tooling2019-01-18809/16/2019
Traditional Trailing Edge (TE) assembly that utilise fixtures for accurate positioning of aircraft (a/c) parts do not allow for removal of specific tooling from the fixtures to travel with the TE, post assembly. Instead, the tooling that positions all the primary a/c assembly datums generally utilise precision pins of various sizes that index and clamp the a/c ribs. Often it is difficult to remove the pins post assembly before the spar can be taken out of the fixture. Use of hammers is common place to hit pins out of holes which is less than ideal considering the a/c parts can be fragile and the tooling is precision set. Also, the Main Assembly Fixture (MAJ) that will receive the TE will inevitably need to relocate some if not all the primary a/c ribs and therefore will most likely be subject to some amount of persuasion. Electroimpact have for many years used cup cone locators that allows static tooling to be temporarily ‘loosened’ and therefore made more compliant for pin insertion/removal, this has been successful to reduce the need for hammering, but doesn’t remove the necessity for extensive manual work to reclaim all the datums. The intent of this paper is to highlight how we, on the C919 project, have successfully designed and implemented the use of removable tooling that travels with the TE sub-assemblies into the main TE assembly fixture and similarly the same interchangeable and removable tooling travels with the completed TE and re-engages with identical tooling receivers in the MAJ. Providing a fast, efficient, reduced man-power and accurate means for building a TE and transfer into the MAJ.
Dineley, James
Nominal High-Altitude Electromagnetic Pulse (HEMP) WaveformsTBMG-348708/1/2019
Even before the Trinity nuclear test in July of 1945, physicists predicted a transient electromagnetic signal would be caused by high-energy photons released from the detonation interacting with the air around the detonation. Predictions of these signals were difficult to make due to the complexity of the physics unleashed by the detonation.
Nominal High-Altitude Electromagnetic Pulse (HEMP) Waveforms19AERP08_088/1/2019
Calculating the characteristics of high-altitude electromagnetic pulses created by the detonation of a nuclear device. Defense Threat Reduction Agency, Fort Belvoir, Virginia Even before the Trinity nuclear test in July of 1945, physicists predicted a transient electromagnetic signal would be caused by high-energy photons released from the detonation interacting with the air around the detonation. Predictions of these signals were difficult to make due to the complexity of the physics unleashed by the detonation. Post-World War II, there was a period of active atmospheric nuclear testing until 1962, during which measurements of these signals were made in order to understand the phenomena that were previously largely viewed as an annoyance and impediment to other instrumentation. The name “electromagnetic pulse” (EMP) began to be used to refer to these signals.
Sensitivity Study on Thermal and Soot Oxidation Dynamics of Gasoline Particulate Filters2019-01-09904/2/2019
Gasoline particulate filters (GPFs) are devices used to filter soot emitted by gasoline direct injection (GDI) engines. A numerical model for a ceria-coated GPF presented in a previous paper by H. Arunachalam et al. in 2017 was developed to predict internal temperature and soot amount combusted during regeneration events. Being that both the internal temperature and the accumulated soot cannot be directly measured during real-time operation and owing to their critical importance for GPF health monitoring as well as regeneration scheduling, the above model turns out to be a valuable tool for OBD applications. In this paper, we first conduct a stochastic analysis to understand the relation between the model parameters and the initial value of the ceria (IV) oxide volume fraction, as a deterministic value for such a state is not known. A particle swarm optimization (PSO) algorithm was employed to define what type of relationship the model parameters were with respect to the initial state of the ceria (IV) oxide volume fraction. A sensitivity study is then conducted over the model parameters to study parameter identifiability from system measurements. Effects of the initial temperature and initial amount of soot were studied as well. Results indicated that the model is most sensitive to the activation energy of GPF regeneration, agreeing with previous studies. Additionally, the model was shown to be able to predict the GPF temperature with less than 5% error when there was at most 20% uncertainty in the parameters. The results of the relationship between ceria (IV) oxide and the parameters, as well as the sensitivity analysis can be used simultaneously in the future for observer-based design.
Takahashi, Aki, Korneev, Slava, Onori, Simona
Study of Performance and Emission Characteristics of Propan-2-ol and Gasoline Fuel Blends in an Unmodified Spark Ignition Engine2019-01-07934/2/2019
In view of the rapid depletion, increasing prices and uneven distribution of conventional petroleum fuels; the interest in the use of alternative fuels has increased exponentially. Fuels such as biodiesel & alcohol have been evaluated both at experimental and commercial scale due to improved emission characteristics as compared to conventional fuels. Alcohols are oxygenated and result in improving the engine performance. As a blend with conventional gasoline, the alcohols enhance the premixed and diffusive combustion phase which improves the combustion efficiency. The present investigation evaluates studies on stability and homogeneity along with physicochemical properties like density, viscosity, calorific value, copper-strip corrosion and solubility at room temperature of Propan-2-ol and gasoline blends. Comprehensive engine trials on unmodified petrol engine fuelled with blends of Propan-2-ol and gasoline blends in the proportions of 5, 10, 15 and 20% by volume have been conducted. The performance characteristics e.g. brake-specific energy consumption, brake thermal efficiency and emissions characteristics such as NOX, CO and HC were studied and analyzed to evaluate the optimum alcohol/fuel blend for the petrol engine. The result yielded enhanced combustion and performance characteristics as compared to gasoline with reduced Carbon monoxide and un-burnt hydrocarbon emissions. However, there was an increase in the oxides of nitrogen emissions.
Kumar, Naveen, Jain, Shikhar, Bagla, Aakriti, Sharma, Shivalika, Tomar, Mukul
Individual Quantum Dots Imaged in 3-D for the First TimeTBMG-338963/1/2019
Researchers have developed an imaging technique that uses a tiny, super sharp needle to nudge a single nanoparticle into different orientations and capture 2-D images to help reconstruct a 3-D picture. The method demonstrates imaging of individual nanoparticles at different orientations while in a laser-induced excited state.
The Effects of Injection Strategies on Particulate Emissions from a Dual-Injection Gasoline Engine2019-01-00551/15/2019
European standards have set stringent PN (particle number) regulation (6×1011 #/km) for gasoline direct injection (GDI) engine, posing a great challenge for the particulate emission control of GDI engines. Dual-injection, which combines direct-injection (DI) with port-fuel-injection (PFI), is an effective approach to reduce particle emissions of GDI engine while maintaining good efficiency and power output. In order to investigate the PN emission characteristics under different dual-injection strategies, a DMS500 fast particle spectrometer was employed to characterize the effects of injection strategies on particulates emissions from a dual-injection gasoline engine. In this study, the injection strategies include injection timing, injection ratio and injection pressure of direct-injection. The experimental results indicated that as the fuel percentage of direct-injection decreased, engine-out particle emissions also gradually declined, with the port-fuel-injection mode yielding the lowest PN emissions. There existed a turning point of direct-injection pulse width, by which the particulate emission characteristics of dual-injection were divided into two different parts. The best direct injection timing in the dual-injection mode to minimize PN emissions was closer to the exhaust top dead center than that in the direct-injection mode. Similar to gasoline-direct-injection, increasing direct-injection pressure in the dual-injection mode also yielded notable reductions in particle number, particle mass and geometry mean diameter (GMD). The experimental results in this paper provide important references for the development and calibration work of dual-injection gasoline engines.
Chen, Wenhao, Xia, Chun, Mao, Kerang, Tao, Jie, Fang, Junhua, Huang, Zhen
LES Analysis on Cycle-to-Cycle Variation of Combustion Process in a DISI Engine2019-01-00061/15/2019
Combustion cycle-to-cycle variation (CCV) of Spark-Ignition (SI) engines can be influenced by the cyclic variations in charge motion, trapped mass and mixture composition inside the cylinder. A high CCV leads to misfire or knock, limiting the engine’s operating regime. To understand the mechanism of the effect of flow field and mixture compositions on CCV, the present numerical work was performed in a single cylinder Direct Injection Spark-Ignition (DISI) engine. A large eddy simulation (LES) approach coupled with the G-equation combustion model was developed to capture the CCV by accurately resolving the turbulent flow field spatially and temporally. Further, the ignition process was modeled by sourcing energy during the breakdown and arc phases with a line-shape ignition model which could move with the local flow. Detailed chemistry was solved both inside and outside the flame front. A compact 48-species 152-reactions primary reference fuel (PRF) reduced mechanism was used. By implementing an adaptive mesh refinement strategy based on the sub-grid scale reaction progress variable, a good balance between accuracy and efficiency was achieved. Compared with the available experimental data, the simulation results showed a satisfying agreement. Furthermore, a correlation analysis was done based on the combustion phasing, peak pressure and gross indicated mean effective pressure (IMEP). Also, the effect of in-cylinder flow field on the early flame development and the peak pressure was discussed under the considered operating condition.
Chen, Ceyuan, Ameen, Muhsin M, Wei, Haiqiao, Iyer, Claudia, Ting, Foochern, Vanderwege, Brad, Som, Sibendu
Heat of Vaporization and Species Evolution during Gasoline Evaporation Measured by DSC/TGA/MS for Blends of C1 to C4 Alcohols in Commercial Gasoline Blendstocks2019-01-00141/15/2019
Evaporative cooling of the fuel-air charge by fuel evaporation is an important feature of direct-injection spark-ignition engines that improves fuel knock resistance and reduces pumping losses at intermediate load, but in some cases, may increase fine particle emissions. We have reported on experimental approaches for measuring both total heat of vaporization and examination of the evaporative heat effect as a function of fraction evaporated for gasolines and ethanol blends. In this paper, we extend this work to include other low-molecular-weight alcohols and present results on species evolution during fuel evaporation by coupling a mass spectrometer to our differential scanning calorimetry/thermogravimetric analysis instrument. The alcohols examined were methanol, ethanol, 1-propanol, isopropanol, 2-butanol, and isobutanol at 10 volume percent, 20 volume percent, and 30 volume percent. The results show that total heat of vaporization of the alcohol gasoline blends is in line with the decreasing heat of vaporization in kilojoules per kilogram with increasing alcohol carbon number, as expected. Mass spectrometer results show that methanol fully evaporates at significantly lower fraction evaporated relative to other alcohols even though it is present at higher molar concentration at a fixed volumetric concentration. Certain alcohols, especially methanol and ethanol, can suppress the evaporation of aromatic compounds such as cumene during the evaporation process in some samples. While the use of mass spectrometry to analyze the composition of the evolving gas mixture provided useful results for a relatively simple research gasoline (FACE B), additional research is required to practically apply this methodology to more complex commercial gasolines.
Fioroni, Gina M., Christensen, Earl, Fouts, Lisa, McCormick, Robert
Fast NGC: A New On-Line Technique for Fuel Flow Measurement2019-01-00621/15/2019
Knowledge of fuel mass injected in an individual cycle is important for engine performance and modelling. Currently direct measurements of fuel flow to individual cylinders of an engine are not possible on-engine or in real-time due to a lack of available appropriate measurement techniques. The objective of this work was to undertake real-time Coriolis fuel flow measurement using GDI injectors on a rig observing fuel mass flow rate within individual fuel injections. This paper evaluates the potential of this technology - combining Coriolis Flow Meters (CFMs) with Prism signal processing together known as Fast Next Generation Coriolis (Fast NGC), and serves as a basis for future transitions on-engine applications. A rig-based feasibility study has been undertaken injecting gasoline through a GDI injector at 150 bar in both single shot mode and at a simulated engine speeds of 1788 and 2978 rpm. The results show that these injections can, in principle, be observed. In addition a number of features of the Fast NGC system unique to gasoline are discussed, and the repeatability of the technique is preliminarily assessed. The study concludes that the Fast NGC system has the potential to measure individual injector flow rates on-engine in real-time.
Leach, Felix, Davy, Martin, Henry, Manus, Malladi, Maruthi Rochishnu, Tombs, Michael, Zhou, Feibiao, Gold, Martin, Pearson, Richard
Knock Sensor Based Virtual Cylinder Pressure Sensor2019-01-00401/15/2019
Typically the combustion in a direct injected compression ignited internal combustion engine is open-loop controlled. The introduction of a cylinder pressure sensor opens up the possibility of a virtual combustion sensor which could enable closed-loop combustion control and thus the potential to counteract effects such as engine part to part variation, component ageing and fuel quality diversity. Closed-loop combustion control requires precise, robust and preferably cheap sensors. This paper presents a virtual cylinder pressure sensor based on the signal from the inexpensive but well proven knock sensor. The method used to convert the knock sensor signal into a pressure estimate included the stages: Phase correcting the raw signal, Filtering the raw signal, Scaling the signal to known thermodynamic laws and provided engine sensors signals and Reconstructing parts of the signal with other known models and assumptions. The modelled cylinder pressure shows high correlation with the measured pressure trace and it was concluded that it is possible to estimate many important combustion parameters - such as maximum pressure, mass fraction burned and total heat release.
Rugland, Christian, Stenlaas, Ola
Fuel & Lubricant Effects on Stochastic Preignition2019-01-00381/15/2019
In this multi-phase study, fuel and lubricant effects on stochastic preignition (SPI) were examined. First, the behavior of fuels for which SPI data had previously been collected were characterized in terms of their combustion and emissions behavior, and correlations between these characteristics and their SPI behavior were examined. Second, new SPI data was collected for a matrix of fuels that was constructed to test and confirm hypotheses that resulted from interpretation of the earlier data in the study and from data in open literature. Specifically, the extent to which the presence of heavy components in the fuel affected SPI propensity, and the extent to which flame initiation propensity affected SPI propensity, were examined. Finally, the interaction of fuels with lubricants expected to exhibit a range of SPI propensities was examined. Although this final dataset did not yield conclusive results, it suggests that additional factors such as engine condition can have a very significant effect on SPI propensity. The main findings of the study are that lower volatility fuel components appear to affect the propensity of the fuel to create initiation events (which could be fuel-oil droplets or deposit breakoff) that can lead to SPI, and further that the ease by which a flame can be established in the bulk mixture correlates to SPI tendency when the initiation event tendency is fixed. The study also showed that neither soot-forming tendency of a fuel nor the fuel’s antiknock quality necessarily correlate to SPI tendency.
Costanzo, Vincent S., Yu, Xin, Chapman, Elana, Davis, Richard, Haenel, Patrick
Estimation of the Fuel Efficiency Potential of Six Gasoline Blendstocks Identified by the U.S. Department of Energy’s Co-Optimization of Fuels and Engines Program2019-01-00171/15/2019
Six blendstocks identified by the Co-Optimization of Fuels & Engines Program were used to prepare fuel blends using a fixed blendstock for oxygenate blending and a target RON of 97. The blendstocks included ethanol, n-propanol, isopropanol, isobutanol, diisobutylene, and a bioreformate surrogate. The blends were analyzed and used to establish interaction factors for a non-linear molar blending model that was used to predict RON and MON of volumetric blends of the blendstocks up to 35 vol%. Projections of efficiency increase, volumetric fuel economy increase, and tailpipe CO2 emissions decrease were produced using two different estimation techniques to evaluate the potential benefits of the blendstocks. Ethanol was projected to provide the greatest benefits in efficiency and tailpipe CO2 emissions, but at intermediate levels of volumetric fuel economy increase over a smaller range of blends than other blendstocks. A bioreformate surrogate blendstock was projected to provide the greatest increase in volumetric fuel economy and the lowest increase in efficiency. Tailpipe CO2 emissions for blends of the bioreformate surrogate were higher at all blend levels compared to the baseline E10 fuel.
Sluder, C. Scott
In-Cylinder GDI Soot via Visualization and Time-Resolved Total Cylinder Sampling2019-01-00371/15/2019
For better understanding, model development and its validation of in-cylinder soot formation processes of Gasoline Direct Injection (GDI) engines, crank-angle-resolved mass and size distribution of in-cylinder soot during a GDI combustion cycle were investigated via optical measurements and total cylinder sampling technique in an optically accessible Rapid Compression and Expansion Machine (RCEM). A direct-injection, spark-ignited and single-shot combustion event was achieved in the RCEM operated with engine speed 600 rpm, compression ratio 9.0, equivalence ratio 0.9 and natural aspiration. A three-component (iso-octane 65%, n-heptane 10%, toluene 25%) gasoline surrogate fuel and a multi-hole injector shared within the Japanese SIP Innovative Combustion Technology research program were used. As for the optical measurements, two-color method and laser/LED-based Diffused Back Illumination (DBI) high-speed imaging through sapphire windows on the cylinder head and the flat-top piston provided time-sequential in-cylinder soot mass. As for the total cylinder sampling, filter gravimetry and Portable Aerosol Mobility Spectrometer (PAMS) measurements of total-cylinder soot-laden gas provided crank-angle-resolved in-cylinder soot mass and size distribution. The total cylinder sampling was realized by replacing the cylinder head window with a stainless-steel diaphragm, rupturing the diaphragm at an arbitrary crank angle during combustion and rapidly expanding the total-cylinder soot-laden gas to effectively freeze secondary reactions and agglomeration of soot particles. The in-cylinder soot mass obtained by the above mentioned four different methods showed reasonable agreement each other both in increasing trend during combustion and quantitative soot mass. Measured variation of soot size distribution during combustion indicates that formation and agglomeration of soot are simultaneously occurring during combustion. Observation and morphology analysis of sampled soot via High-Resolution Transmission Electron Microscopy (HR-TEM) are also in progress.
Maruyama, Tomohisa, Sato, Yoshiumi, Endo, Kazuki, Tsukamoto, Takamichi, Aizawa, Tetsuya
Benchtop Investigation of Filtration Efficiency and Pressure Drop Behavior of Commercial High Porosity Gasoline Particulate Filters2019-01-00541/15/2019
The increasing number of gasoline direct injection (GDI) vehicles on the roads has drawn attention to their particulate matter (PM) emissions, which are greater both in number and mass than port fuel injected (PFI) spark ignition (SI) engines [1]. Regulations have been proposed and implemented to reduce exposure to PM, which has been shown to have negative impacts on both human health and the environment [2, 3]. Currently, the gasoline particulate filter (GPF) is the proposed method of reducing the amount of PM from vehicle exhaust, but modifications to improve the filtration efficiency (FE) and reduce the pressure drop across the filter are yet needed for implementation of this solution in on-road vehicles. This work evaluates the impacts of wall thickness and cell density on filtration efficiency and backpressure using a benchtop filtration system. For both unmodified and modified GPFs, the filtration efficiency was studied using a scanning mobility particle sizer (SMPS), and the pressure drop across the filter was obtained using a differential pressure transducer. The performance of the unmodified GPFs were investigated at three space velocities: 15,000 hr-1, 30,000 hr-1, and 60,000 hr-1. Increasing space velocity through unmodified GPFs results in decreasing FE by approximately 5% for every 15,000 hr-1 increase, which means a GPF has its lowest FE and highest pressure drop at 60,000 hr-1. The GPF with lowest initial FE and pressure drop, 300-10, was modified by preloading calcium sulfate (CaSO4) to form a cake layer on the walls. The improvement of about 10% to the filtration efficiency and increase of about 6% to the pressure drop when loaded to 20 g/L indicates that a preloaded cake layer can improve performance with less penalty than increasing wall thickness.
Porter, Quinton, Strzelec, Andrea
Mechanism Analysis on the Effect of Fuel Properties on Knocking Performance at Boosted Conditions2019-01-00351/15/2019
In recent years, boosted and downsized engines have gained much attention as a promising technology to improve fuel economy; however, knocking is a common issue of such engines that requires attention. To understand the knocking phenomenon under downsized and boosted engine conditions deeply, fuels with different Research Octane Number (RON) and Motor Octane Number (MON) were prepared, and the knocking performances of these fuels were evaluated using a single cylinder engine, operated under a variety of conditions. Experimental results showed that the knocking performance at boosted conditions depend on both RON and MON. While higher RON showed better anti-knocking performance, lower MON showed better anti-knocking performance. Furthermore, the tendency for a reduced MON to be beneficial became stronger at lower engine speeds and higher boost pressures, in agreement with previously published modelling work. A new method of interpreting octane appetite is presented which relates the gradient of contour lines of MB50 in RON/MON space to K value. The results can be further interpreted by understanding the relative contribution of low temperature oxidation (LTO) pathways under the prevailing temperature/pressure conditions in the engine.
Kassai, Masaharu, Aksu, Cagdas, Shiraishi, Taisuke, Cracknell, Roger, Shibuya, Masahiko
An Experimental Study of the Effects of Coolant Temperature on Particle Emissions from a Dual Injection Gasoline Engine2019-01-00511/15/2019
Euro VI emission standards have set a very strict limitation on particulate matter emissions of Gasoline Direct Injection (GDI) engine. It is difficult for GDI engine to meet the Euro VI PN regulation (6×1011#/km) without a series of complicated after-treatment devices such as Gasoline Particulate Filter (GPF). Previous research shows that GDI vehicles under cold start condition account for more than 50% of both particle number and mass emissions during the entire NEDC driving cycle. Dual Injection Gasoline engine is based on the GDI engine by adding a set of port fuel injection system. The good mixing characteristics of the port fuel injection system can help to reduce the particulate matter emissions of the GDI engine during the cold start condition. In this study, a Cambustion DMS500 fast particle spectrometer was employed to characterize the effects of coolant temperature and direct injection ratio on particulate emissions from a turbocharged four-cylinder dual-injection gasoline engine. The experimental results showed that with the coolant temperature increasing the particulate matter tended to be consistent under the port fuel injection mode. The particulate matter showed significantly drop with the coolant temperature increasing both in the dual injection mode and the direct injection mode. At the same coolant temperature, with the decrease of the direct injection ratio, the particulate matter showed notably reductions, and with the increase of coolant temperature, the magnitude of the reductions gradually declined. The experimental results provided important guidance to reduce the particulate matter via dual injection mode during the cold start condition.
Xia, Chun, Chen, Wenhao, Fang, Junhua, Huang, Zhen
Future Fuels for DISI Engines: A Review on Oxygenated, Liquid Biofuels2019-01-00361/15/2019
Global warming and climate change have led to a greater interest in the implementation of biofuels in internal combustion engines. In spark ignited engines, biofuels have been shown to improve efficiency and knock resistance while decreasing emissions of unburned hydrocarbons, carbon monoxide and particles. This study investigates the effect of biofuels on SI engine combustion through a graphical compilation of previously reported results. Experimental data from 88 articles were used to evaluate the trends of the addition of different biofuels in gasoline. Graphs illustrating engine performance, combustion phasing and emissions are presented in conjunction with data on the physiochemical properties of each biofuel component to understand the observed trends. Internal combustion engines have the ability to handle a wide variety of fuels resulting in a broad range of biofuel candidates. Three groups of oxygenated liquid biofuels were investigated in this review: alcohols, ethers and furans. While the investigated alcohols showcase properties associated with increased engine efficiencies (such as higher chemical knock resistance, greater charge cooling and faster laminar flame speeds). They also pose the challenge of greater fuel consumption due to lower energy densities than gasoline. Ethers and furans, on the other hand are favored by current engine designs as they exhibit properties (such as the energy density) closer to gasoline alongside increased chemical knock resistance. The compiled data summarizes the possibilities to improve efficiency and fuel economy for biofuel and binary blends in SI engines. However, the results also, show that some of the trends are more complex than anticipated. The effect of biofuels on combustion speed, regulated emissions and exhaust temperatures are not proven to be as self-evident as reported in previous studies. Results on multiple blends with focus on the effect of blending on properties would help improve the picture of the effect of future fuels on SI combustion.
Larsson, Tara, Stenlaas, Ola, Erlandsson, Anders
Regulation vs. Field Data: Managing Fuel Quality2019-26-01571/9/2019
Unlike in the aviation and marine sector, fuel specification in the on-road transportation sector are varied depending on the countries. Globally, the countries are going towards ultra-low sulfur fuels. In developed countries including in EU and the U.S., ultra-low sulfur fuels have been used since 2005-2006. In Asia, Japan lead the region with less than 10 ppm sulfur fuels introduced into the market in January 2005. More than a decade later, fuels with high sulfur content are still sold in most countries in Asia, Africa, the Middle East and Pacific. Facing pressure from environmentalists, these countries are focusing on sulfur reduction in their conventional fuels, along with improvement in their conventional fuels, along with improvement in their vehicle emission standards. On the other hand, in more advanced countries where they already have the cleanest possible conventional fuels, alternative fuels vehicles including electric vehicles are getting more attentions. Governments of developing countries are setting higher fuel quality standards to enable the implementation of more stringent vehicle emission standards. However, lack of fuel quality monitoring system in those countries results in the use of off-spec fuels. SGS worldwide market data delivers many examples. In the Philippines, 83% of premium plus gasoline samples have RON of 93 - 96.5 against the minimum requirement of 97 in the period of 2011-2017. Another example: 11.28 vol.% of methanol was found in a gasoline sample in 2016-2017 in the Philippines despite the specifications do not allow methanol to be present. One more example from Pakistan: the Manganese presence in all gasoline samples with concentration from 0.1 to 104 mg/kg in 2003-2017. Prolonged use of off-spec fuels will deteriorate exhaust emissions, damage the vehicles and worsen air quality. Therefore, a good understanding of fuel specifications and implementation of a good fuel quality monitoring system are needed to avoid severe productivity loss due to stalled vehicles on the road
Nurafiatin, Lucky
Diminishing Benefits of Federal Reformulated Gasoline (RFG) Compared to Conventional Gasoline (CG)04-12-01-000112/20/2018
The Federal reformulated gasoline (RFG) program originated with the 1990 Clean Air Act Amendments to address high ozone and air toxics levels in major urban areas. These areas include portions of 17 states and represent approximately 30% of the total U.S. gasoline volume. Initially, formulation changes were limited to addition of oxygen and reductions in benzene and fuel Reid vapor pressure (RVP) levels. These reformulations were intended to meet minimum emissions reduction targets for volatile organic compounds (VOCs), air toxics, and oxides of nitrogen (NOx) when compared to a 1990 baseline gasoline in a “1990 technology” vehicle fleet. The United States Environmental Protection Agency (U.S. EPA) developed two computational models, the Simple Model in 1995 and the Complex Model in 1998, for use in demonstrating compliance with the regulations. This article reviews the derivation and evolution of the RFG program. Initially, RFG’s emissions reduction benefits compared to conventional gasoline (CG) resulted primarily from differences in fuel sulfur levels, benzene content, and RVP. However, due to other regulatory changes over the past two decades, the compositions of CG and RFG have nearly converged. Inserting annual average gasoline properties into the Complex Model shows that RFG’s predicted NOx and toxics reduction benefits have largely disappeared, while a VOC reduction benefit persists. This benefit results from CG’s higher summertime vapor pressure, due to the 1 psi RVP increase that is allowed for CG containing 10 vol.% ethanol. Due to fleet turnover and introduction of low-emitting, advanced technology vehicles, fleet-wide vehicle emissions have decreased dramatically over the past 20 years. Considering this, along with the general erosion of RFG’s emissions reduction benefits, it is unlikely that RFG provides any demonstrable air quality benefit compared to CG today. RFG’s residual VOC benefit likely could be maintained by application of simpler RVP controls, rather than by continuation of the outdated RFG program.
Hoekman, S. Kent, Leland, Amber, Bishop, Gary
Influence of Autoignition and Pressure Wave Behavior on Knock Intensity Based on Multipoint Pressure Measurement and In-Cylinder Visualization of the End Gas2018-32-000110/30/2018
In this study, the effect of autoignition behavior in the unburned end-gas region on pressure wave formation and knock intensity was investigated. A single-cylinder gasoline engine capable of high-speed observation of the end gas was used in the experiments. Visualization in the combustion chamber and spectroscopic measurement of light absorption by the end gas were carried out to analyze autoignition behavior in the unburned end-gas portion and the reaction history before autoignition. The process of autoignition and pressure wave growth was investigated by analyzing multipoint pressure histories. As a result, it was found that knocking intensity increases through interaction between autoignition and pressure waves.
Yamashita, Takahiro, Takahata, Shuhei, Kudo, Hiroki, Izako, Takuya, Ishikawa, Takahiro, Saito, Masanori, Tanabe, Mitsuaki, Iijima, Akira
Influences of Butanol Blends on Combustion and Emissions of a Small SI Engine2018-32-005810/30/2018
In the general efforts to replace the fossil fuels in transportation by renewable fuels the bioalcohols are an important alternative. The global share of Bioethanol used for transportation is continuously increasing. Butanol, a four-carbon alcohol, is considered in the last years as an interesting alternative fuel, both for Diesel and for Gasoline application. Its advantages for engine operation are: good miscibility with gasoline and diesel fuels, higher calorific value than Ethanol, lower hygroscopicity, lower corrosivity and possibility of replacing aviation fuels. In the present work research with different nButanol portions in gasoline (BuXX)* was performed on the 2-cylinder SI engine with variations of several parameters on engine dynamometer. At different steady state operating points were varied: spark timing (αz), air excess factor (λ) and EGR-rate. Furthermore, the conversion rates and light-off of a 3-way-catalyst were investigated. As research tools the combustion pressure indication and the exhaust gas analysis were used. In the steady state operation, it was found that Bu-blends generally reduce the emissions of CO, HC, NOx in untreated exhaust gas and have a very little influence on catalytic conversion rates of the 3-way-catalyst. At lower engine part load, “Bu” shortens the inflammation lag and reduces the cyclic dispersion of combustion. Nevertheless, this advantage disappears at higher engine loads and with higher “Bu” portions. The present paper shows some examples of the most important results.
Czerwinski, Jan, Güdel, Martin, Engelmann, Danilo, Pechout, Martin
A Study of the Factors Determining Knocking Intensity Based on High-Speed Observation of End-Gas Autoignition Using an Optically Accessible Engine2018-32-000310/30/2018
The purpose of this study was to investigate how autoignition leads to the occurrence of pressure oscillations. That was done on the basis of in-cylinder visualization and analysis of flame images captured with a high-speed camera using an optically accessible engine, in-cylinder pressure measurement and measurement of light emission from formaldehyde (HCHO). The results revealed that knocking intensity tended to be stronger with a faster localized growth speed of autoignition. An investigation was also made of the effect of exhaust gas recirculation (EGR) as a means of reducing knocking intensity. The results showed that the application of EGR advanced the ignition timing, thereby reducing knocking intensity under the conditions where knocking occurred.
Ishikawa, Takahiro, Takahata, Shuhei, Kudo, Hiroki, Izako, Takuya, Yamashita, Takahiro, Koga, Hibiki, Kiura, Toshiro, Iijima, Akira
Effect of Fuel Injection Timing on the Mixture Preparation in a Small Gasoline Direct-Injection Engine2018-32-001410/30/2018
Gasoline direct-injection (GDI) engines have evolved as a solution to meet the current demands of the automotive industry. Benefits of a GDI engine include good fuel economy, good transient response, and low cold start emissions. However, they suffer from problems, like combustion instability, misfire, and impingement of fuel on in-cylinder surfaces. Therefore, to highlight the influence of fuel injection timing on in-cylinder flow, turbulence, mixture distribution and wall impingement, a computational study is conducted on a small-bore GDI engine. Results showed that air motion inside the engine cylinder is influenced by direct-injection of fuel, with considerable variation in turbulent kinetic energy at the time of injection. Due to charge cooling effect, mixture density and trapped mass were increased by about 10.8% and 9.5%, respectively. A significant drop in mean in-cylinder temperature (about 100 °C) was observed with direct-injection of fuel as compared to the case without injection, with further variation based on injection timing. Fuel distribution near the spark plug and fuel impingement on in-cylinder surfaces are carefully evaluated. An early injection at 80 crank angle degree after top dead center of intake provided the best fuel distribution and minimum wall impingement. At the time of spark, in-cylinder turbulence was also found to be higher for this injection timing. Experimental results also indicated relatively higher brake thermal efficiency and lower emissions with early fuel injection timings, located around the mid of intake.
Jose, Jubin, Parsi, Anil, Shridhara, Shrinidhi, Mittal, Mayank, Ramesh, A
Mixture Formation and Combustion Evaluation of a Motorcycle Engine Concept Equipped with One Fuel Injector for Each Intake Valve2018-32-000910/30/2018
In light of a more stringent emission legislation and in anticipation of possible future measures to further reduce the real environmental impact of motorcycles, it is necessary to develop engine concepts which are efficient and low on emissions in a wide range of operating points. This poses an important challenge on the development of high performance motorcycles engines as their focus on full load behaviour conflicts sharply with the emission and efficiency demands of the remaining engine load map. The focus of this paper is to evaluate the potential of a port fuel injection (PFI) concept consisting of one individual fuel injector for each intake valve to solve this trade-off. Previous research shows a positive effect of such a setup on mixture formation due to better targeting and atomization, reducing HC emissions and cyclic variations. It also shows improved efficiency, performance and knocking characteristics caused by an enhanced charge cooling effect through open valve injection (OVI). Although the system has been previously investigated, the necessary layout considerations and impacts of the system for a high performance motorcycle engine have not yet been addressed. In this work the mentioned PFI concept was studied using a high performance two-cylinder motorcycle engine. Engine tests were conducted for two injector sets having different static flow values. The results showed improved efficiency and lower HC emissions for higher engine loads, but no performance gain at full load. The reasons for this behaviour were closely analysed by means of CFD simulation and thermodynamic loss analysis of the combustion process. These explanations were further confirmed by additional engine tests using exhaust gas sampling with fast FID. As a final result a set of recommendations for further concept improvement is proposed.
Gaitan, Pedro, Schwarz, Frank, Eibl, Rüdiger
Experimental Study of Spark-Assisted Auto-Ignition Gasoline Engine with Octagonal Colliding Pulsed Supermulti-Jets and Asymmetric Double Piston Unit2018-32-000410/30/2018
Much effort has been devoted to studies on auto-ignition engines of gasoline including homogeneous-charge combustion ignition engines over 30 years, which will lead to lower exhaust energy loss due to high-compression ratio and less dissipation loss due to throttle-less device. However, the big problem underlying gasoline auto-ignition is knocking phenomenon leading to strong noise and vibration. In order to overcome this problem, we propose the principle of colliding pulsed supermulti-jets. In a prototype engine developed by us, octagonal pulsed supermulti-jets collide and compress the air around the center point of combustion chamber, which leads to a hot spot area far from chamber walls. After generating the hot spot area, the mechanical compression of an asymmetric double piston unit is added in four-stroke operation, which brings auto-ignition of gasoline. In our previous report (SAE paper 2016-01-2336) using gasoline, there were only some engine cycles indicating high thermal efficiency comparable to that of diesel engines. In the present report, we show that spark-assisted auto-ignition combustion optimized with the hot spot area generated by octagonal pulsed supermulti-jets indicates potential of high thermal efficiency averaged during many cycles, which is about the same level of diesel engines. Mechanical compression ratio is about from 7.8:1 to 11:1 and engine speed is 2,000 rpm under the part load whose exhaust air-fuel ratio is about from 20 to 30. Moreover, experimental data obtained also show the increasing rate of pressure after combustion is less than the knocking limit of reciprocating engines. And we have made a new prototype engine whose asymmetric double piston unit moves non-sinusoidally. We intend to report progress of this new prototype engine.
Isshiki, Yuuki, Naitoh, Ken, Onuma, Yuichi, Ohara, Soichi, Arai, Daisuke, Machida, Yutaka, Ito, Hajime, Kobayashi, Yoshiki, Suzuki, Takahiro, Tada, Yusuke
Study on Knocking Characteristics for High-Efficiency Operation of a Super-Lean Spark Ignition Engine2018-32-000210/30/2018
This study investigated the influence of EGR and spark advance on knocking under high compression ratio, ultra-lean mixture and supercharged condition using premium gasoline as a test fuel. A high-compression ratio, supercharged single cylinder engine was used in this experiment. As a result, the period from ignition to autoignition was prolonged. In addition, knock intensity was drastically reduced. In other words, it is inferred that by combining an appropriate amount of EGR and spark advance, high efficiency operation avoiding knocking can be realized.
Nishiyama, Takeshi, Agui, Keito, Togawa, Masaaki, Saito, Masanori, Tanabe, Mitsuaki, Iijima, Akira
Automotive Engineering: October 201818AUTP1010/4/2018
Transforming Tenneco From new-tech suspensions to curb motion sickness, to composite exhausts, Dr. Ben Patel's engineers are innovating toward the electrified, automated-driving future. The electric future-Audi-style The first-ever electric vehicle from Audi, the e-tron, is production-ready and as expected, impressively engineered. Dual-volute salute! BorgWarner's new twist in turbocharging helps GM's new L3B gasoline four deliver V6-beating power and torque, with diesel-like fuel efficiency, in full-size pickup trucks. Editorial OEMs deny suppliers the limelight SAE Standards News Battery-size standards Technical Information Report available Supplier Eye The future of "core" vehicle systems The Navigator Ideas for multi-modal mobility What We're Driving VinFast: Vietnam's first car company has big ambitions Mercedes-Benz getting serious about fuel-cells-for vans Autonomous vehicles present passive-safety challenges Millers Oils tackles EV lubrication challenges OEMs progress to 'functional engineering' as digital tools evolve Schaeffler debuts new Mover concept at Detroit symposium With 2019 Sierra, GMC puts brand differentiation behind it-literally 2019 Honda Pilot gets refined 9-speed, tougher styling Subaru 'Ascends' to three-row crossover segment Toyota 'hatches' new Corolla variant Q&A Renovo Auto's Chris Heiser on OS for AMoD
An Optical Study on the Combustion of Gasoline/PODEn Blends in a Constant Volume Vessel2018-01-17489/10/2018
Polyoxymethylene dimethyl ethers (PODEn) have high cetane number, high oxygen content and high volatility, therefore can be added to gasoline to optimize the performance and soot emission of Gasoline Compression Ignition (GCI) combustion. High speed imaging was used to investigate the spray and combustion process of gasoline/PODEn blends (PODEn volume fraction 0%-30%) under various ambient conditions and injection strategies in a constant volume vessel. Results showed that with an increase of PODEn proportion from 10% to 30%, liquid-phase penetration of the spray increased slightly, ignition delay decreased from 3.8 ms to 2.0 ms and flame lift off length decreased 29.4%, causing a significant increase of the flame luminance. For blends with 20% PODEn, when ambient temperature decreased from 893 K to 823 K, the ignition delay increased 1.3 ms and the flame luminance got lower. When increasing the injection pressure, the liquid phase length and the ignition delay got a little longer and the flame luminance and flame duration decreased. Long spray results showed that soot formed in higher PODEn flames oxidized earlier and quicker. The parameter changes that can extend the ignition delay all gave rise to the decrease of flame luminance because of the increase of the proportion of premixed combustion.
Ma, Yue, Cui, Longxi, Ma, Xiao, Wang, Zhi, Shuai, Shi-Jin
Engine Accelerated Aging Method Developed to Study the Effect of Lubricant Formulations on Catalyzed Gasoline Particulate Filter Durability2018-01-18049/10/2018
Catalyzed gasoline particulate filter (cGPF) is the prime technology to meet future stringent regulations for particulates from gasoline direct injection (GDI) engines. One of the technical concerns is the ultimate durability of cGPF in regards to engine lubricant formulations. This study investigated two tailored lubricant formulations on catalyzed GPFs which were aged on engine followed by emission testing on vehicle. An engine accelerated aging protocol was developed for cGPFs to simulate thermal aging, ash and soot loading that is at least equivalent to 200,000 km durability requirement. Evaluations include tailpipe emission levels, backpressure, catalytic performance, and post-mortem analysis. Both formulations have demonstrated a high level of cGPF performance retention; performance being assessed in terms of emission level at the end of durability demonstration testing. These formulations provide flexibility in selecting robust lubricant to meet various system requirements.
Shao, Huifang, Carpentier, Guillaume, Yin, Danhua, Wang, Yinhui, Remias, Joesph, Roos, Joseph, Xia, Wenzheng, Zheng, Yi, Yuan, Xinbo, Yang, Dongxia, He, Xiaokun, Yin, Zenghui
Dual Fuel Injection (DI + PFI) for Knock and EGR Dilution Limit Extension in a Boosted SI Engine2018-01-17359/10/2018
Combined direct and port fuel injection (i.e., dual injection) in spark ignition engines is of increasing interest due to the advantages for fuel flexibility and the individual merits of each system for improving engine performance and reducing engine-out emissions. Greater understanding of the impact of dual injection will enable deriving the maximum benefit from the two injection systems. This study investigates the effects of dual injection on combustion, especially knock propensity and tolerance to exhaust gas recirculation (EGR) dilution at different levels of EGR. A baseline for comparison with dual injection results was made using direct injection fueling only. A splash blended E20 fuel was used for the direct injection only tests. For the dual injection tests, gasoline, representing 80% by volume of the total fuel, was injected using the direct injector, and ethanol, representing 20% by volume of the total fuel, was injected using the port fuel injector. EGR mass fraction was varied from 0% to 21%, under boosted intake air pressure of 1.25 bar for both injection strategies. The results showed dual injection was beneficial to shorten the burn duration and improve combustion stability. Dual injection was more sensitive to knock than direct injection primarily due to increased unburned gas temperature. The overall thermal efficiency for the two injection types was comparable. The particulate matter emissions from dual injection showed slightly lower values, and the gaseous emissions showed lower total hydrocarbons and similar nitrogen oxides compared with only using direct injection of E20.
Han, Taehoon, Lavoie, George, Wooldridge, Margaret, Boehman, André
Methodical Selection of Sustainable Fuels for High Performance Racing Engines2018-01-17499/10/2018
As the importance of sustainability increases and dominates the powertrain development within the automotive sector, this issue has to be addressed in motorsports as well. The development of sustainable high-performance fuels defined for the use in motorsports offers technical and environmental potential with the possibility to increase the sustainability of motorsports at the same or even a better performance level. At the moment race cars are predominantly powered by fossil fuels. However due to the emerging shift regarding the focus of the regulations towards high efficient powertrains during the last years the further development of the used fuels gained in importance. Moreover during the last decades a huge variety of sustainable fuels emerged that offer a range of different characteristics and that are produced based on waste materials or carbon dioxide. This study investigates the question of which sustainable fuels offer the characteristics suitable for high-performance race engines. Equivalents to gasoline, diesel and natural gas are examined separately in order to present the options with various engine concepts. The requirements for a high-performance fuel are defined based on experimental investigations emphasizing among other characteristics the importance of the knock resistance for gasoline-like fuels and the ignitability for diesel-like fuels. Furthermore the characteristics of the sustainable alternatives are analyzed. On the basis of the experimental results a comparison is carried out to match the fuel requirements with the characteristics and to select the optimal equivalent for fossil gasoline, diesel and natural gas. Moreover the sustainable fuels are evaluated with an environmental analysis including the fuel life cycle. The results show a potential to reduce the greenhouse gas emissions per mega joule energy content by up to 88%. This research assesses the broad variety of sustainable biologic and synthetic fuels concerning the potential use in motorsports and the resulting environmental benefits.
Schwarz, Lea, Bargende, Michael, Dreyer, Stefan, Baretzky, Ulrich, Kotauschek, Wolfgang, Wohlgemuth, Sebastian, Bach, Florian
Holistic Evaluation of CO 2 Saving Potentials for New Degrees of Freedom in SI Engine Process Control Based on Physical Simulations2018-01-16549/10/2018
Specific shifting of load points is an important approach in order to reduce the fuel consumption of gasoline engines. A potential measure is cylinder deactivation, which is used as a study example. Currently CO2 savings of new concepts are evaluated by dynamic cycles simulations. The fuel consumption during driving cycles is calculated based on consumption-optimized steady-state engine maps. Discrete load point shifts occur as shifts within maps. For reasons of comfort shifts require neutral torque. The work of deactivated cylinders must be compensated by active cylinders within one working cycle. Due to the larger time constant of the air path the air charge must be increased or decreased in order to deactivate or activate cylinders without affecting the torque. A working-cycle-resolved, continuously variable parameter is prerequisite for process control. Manipulation of ignition timing enables a reduction of efficiency and gained work. So far dynamic cycle simulation does not take into account additional fuel consumption due to shifts of operating points. A new method is developed to investigate the influence of these highly dynamic operating events on total CO2 savings. Relevant operating point shifts are determined by dynamic cycle simulations. Additional fuel consumption is calculated by use of a one-dimensional model of air path and a predictive zero-dimensional model of the combustion chamber. A wheel-neutral discrete shift of operating points is controlled by automatically generated setpoint trajectories of process parameters. Applying cost functions enables the evaluation of different degrees of freedom in process control independently from the controller’s quality. After calculating setpoint trajectories for an engine configuration the results are applicable to further driving cycles and vehicle configurations without additional effort. This method is examined on various driving cycles. Taking into account the consumption by shift operations the advantages of cylinder deactivation in cycle simulation decrease with increasing operating dynamics.
Wandschneider, Tim, Wiege, Katharina, Gottschalk, Wolfram
Distribution of Knock Frequencies in Modern Engines Compared to Historical Data2018-01-16669/10/2018
It is widely known that the rapid autoignition of end-gas will cause an engine cylinder to resonate, creating a knocking sound. These effects were quantified for a simple engine geometry in 1934 in a study where critical resonance frequencies were identified. That analysis, performed by Charles Draper, still forms the basis of most knock studies. However, the resonance frequencies are highly dependent on the engine geometry and the conditions inside the cylinder at autoignition. Since, engines and fuels operate at substantially different conditions than they did in 1934, it is expected that there should be a shift in knock frequencies. Experimental tests were run to collect knock data in an engine, representative of modern geometries, over a range of operating conditions for a number of different fuels. The operating conditions-intake air temperature, intake air pressure, and engine speed-were varied to identify shifts in the critical frequencies. Additionally, fuels were varied in octane number from 80 to 100. The resulting analysis found that the first circumferential mode, at approximately 6 kHz still played a substantial role in knock in modern engines. However, the analysis also found a decreased contribution from radial modes and an increased contribution from the axial modes. The distributions of frequencies did not shift significantly for changes in the intake air temperature or pressure; however, the axial modes became more significant at higher engine speeds. Additionally, the axial modes increase in frequency for higher octane fuels, which have an earlier knock-limited spark advance. These results show the increased importance of the axial modes in knock for modern engines; these modes are typically not audible, though they can still result in engine damage.
Mittal, Vikram
Impact of Engine Age and Engine Hardware on Low-Speed Pre-Ignition2018-01-16639/10/2018
Low-speed pre-ignition (LSPI) is a well-studied phenomenon in boosted, spark ignition engines. The impact of lubricant formulation has received a lot of attention in recent years, yet the impact of engine hardware and engine wear on LSPI is still not fully understood. This paper addresses some of these questions using results from multiple installations of the GM 2.0 L LHU engine platform. In the first part of the study, the effect of engine life on LSPI activity was observed, and it was found that engines were susceptible to variations in LSPI activity during the initial LSPI tests with the activity eventually reaching a “stabilized” level. It was further observed that the LSPI activity generally continued to decline at a steady rate as the engine aged. For engines used in LSPI testing, the life of the engine is often limited as LSPI activity decays with age. This reduction in LSPI activity may correlate to the engine liner wear and it is suggested that the amount of oil transport along the engine liner, which is a function of the liner roughness amongst other factors, is a dominant mechanism for this observed reduction. This observation highlights the importance of baseline testing throughout the life of the engine which is critical for severity adjustments of oils tested at different times. The effect of hardware component replacement on LSPI activity was also investigated. It was determined that the removing, cleaning, and replacing of both pistons and rings had no effect on LSPI activity and did not require re-stabilization of the test engine.
Kalaskar, Vickey B., Swarts, Andre, Alger, Terrence
Detonation Peninsula for TRF-Air Mixtures: Assessment for the Analysis of Auto-Ignition Events in Spark-Ignition Engines2018-01-17219/10/2018
Controlling abnormal auto-ignition processes in spark-ignition engines requires understanding how auto-ignition is triggered and how it propagates inside the combustion chamber. The original Zeldovich theory regarding auto-ignition propagation was further developed by Bradley and coworkers, who highlighted different modes by considering various hot spot characteristics and thermodynamic conditions around them. Dimensionless parameters (ε, ξ) were then proposed to classify these modes and to define a detonation peninsula for H2-CO-air mixtures. This article deals with numerical simulations undertaken to check the relevancy of this original detonation peninsula when considering realistic gasoline fuels. 1D calculations of auto-ignition propagation are performed using the Tabulated Kinetics for Ignition model. Chemical kinetics calculations are first carried out to build the needed look-up table for the auto-ignition delay time τi, and the excitation times τe of E10-air mixtures using a RON 95 TRF surrogate. The dimensionless parameter ε is based on the hot spot radius and on the excitation time τe of the fuel. Previous chemical kinetics calculations confirm the impact of the fuel on this parameter as H2-CO-air mixtures feature much longer excitation times than TRF-air mixtures. Focusing on the parameter ξ, its estimation depends on hot spots characteristics and thermodynamic conditions. The limits of the peninsula therefore vary depending on initial conditions and hot spot characteristics, that is why this paper focuses on several conditions to validate the dependency of the boundaries between the different auto-ignition modes. Hundreds of simulations are performed and due to the large amount of calculations, a specific post-processing methodology is defined to determine the auto-ignition propagation modes by automatically characterizing the coupling conditions between reaction and pressure waves. Several new detonation peninsulas are finally proposed depending on initial conditions in terms of temperature, pressure, fuel-air equivalence ratio and dilution. Limits of the detonation peninsula for TRF-air mixtures are more affected depending on each operating conditions. These new limits can finally be used to better understand abnormal auto-ignition events in spark-ignition engines.
Guerouani, Ahmed, Robert, Anthony, Zaccardi, Jean-Marc
Homogeneous Lean Combustion in a 2lt Gasoline Direct Injected Engine with an Enhanced Turbo Charging System2018-01-16709/10/2018
In the quest for a highly efficient, low emission and affordable source of passenger car propulsion system, meeting future demands for sustainable mobility, the concept of homogeneous lean combustion (HLC) in a spark ignited (SI) multi-cylinder engine has been investigated. An attempt has been made to utilize the concept of HLC in a downsized multi-cylinder production engine producing up to 22 bar BMEP in load. The focus was to cover as much as possible of the real driving operational region, to improve fuel consumption and tailpipe emissions. A standard Volvo two litre four-cylinder gasoline direct injected engine operating on commercial 95 RON gasoline fuel was equipped with an advanced two stage turbo charger system, consisting of a variable nozzle turbine turbo high-pressure stage and a wastegate turbo low-pressure stage. The turbo system was specifically designed to meet the high demands on air mass flow when running lean on higher load and speeds. Also, a dual coil ignition system was used for enhanced ignition ability and a lean NOx emissions exhaust after-treatment system (EATS) dummy was fitted downstream the turbo to receive representative exhaust pressures and temperatures for further development purposes. The engine was mapped running lean in various load points in the operational area of interest. It was found that the engine could sustain a high degree of dilution in lower engine speeds and intermediate loads. Fuel consumption improvements of 12% were obtained running at 1500 rpm and 10 bar BMEP at lambda 1.8. At higher engine loads, above 10 bar BMEP, it was found that the combustion stability deteriorated. The ignition could not be optimized due to knocking combustion and at the same time, combustion duration, measured in crank angle degrees, increased with increasing en-leanment and engine speed, leading to late combustion phasing and large variation in cycle-to-cycle of NMEP. This is currently limiting the operational region of lean combustion of the engine used. The load limit in lean operation was investigated, assessing combustion variations and knock phenomena under different operating conditions.
Clasen, Kristoffer, Koopmans, Lucien, Dahl, Daniel
Effect of Mixture Formation and Injection Strategies on Stochastic Pre-Ignition2018-01-16789/10/2018
Stochastic pre-ignition remains one of the major barriers limiting further engine downsizing and down-speeding; two widely used strategies for improving the efficiency of spark-ignited engines. One of the most cited mechanisms thought to be responsible for pre-ignition is the ignition of a rogue droplet composed of lubricant oil and fuel. This originates during mixture formation from interactions between the fuel spray and oil on the cylinder liner. In the present study, this hypothesis is further examined using a single cylinder supercharged engine which employs a range of air-fuel mixture formation strategies. These strategies include port-fuel injection (PFI) along with side and central direct injection (DI) of an E5 gasoline (RON 97.5) using single and multiple injection events. Computational fluid dynamic (CFD) calculations are then used to explain the observed trends. Overall, this study reinforces that interactions between the fuel spray and oil on the cylinder liner can be an important contributor towards stochastic pre-ignition. The occurrence of pre-ignition, as shown by CFD calculations, is successful after completion of two stages. The first stage involves the formation of precursors from interactions between the fuel spray and oil on the cylinder liner. This is shown to be dependent upon the mass of the fuel impinging on the cylinder liner. The second stage involves the ignition of the precursor, which is shown to be dependent upon the temperature of the air-fuel mixture near top dead center.
Singh, Eshan, Mubarak Ali, Mohammed Jaasim, Ichim, Adrian, Morganti, Kai, Dibble, Robert
Characterizing Spray Propagation of GDI Injectors under Crossflow Conditions2018-01-16969/10/2018
In DISI engines spray distribution and atomization directly influence mixture formation, the quality of combustion and the resulting emissions. Constant Volume Chambers (CVC) are commonly used to characterize sprays of gasoline injectors. The CVCs provide good optical access but the flow condition of the engine cannot be reproduced. Optically accessible engines in contrast deliver realistic flow conditions but have restricted optical access. In former investigations we compared the spray propagation of different injectors in constant volume chambers and in optical accessible engines. These results showed a clear difference of the spray propagation in the CVC and the engine, especially at high charge motion conditions in the engine. To find an appropriate way to investigate the impact of different charge motion a flow channel was built with adjustable crossflow velocities from 5-50 m/s. The spray propagation during the injection process was measured with high-speed shadowgraphy. Two main parameters are introduced to describe the crossflow stability. The location of the intensity center represents the global spray deflection. The second parameter is the ratio between the areas of high and low optical spray density to express the spray “blow-out” under crossflow conditions. Five different injectors were investigated at injection pressures between 100 bar and 170 bar to determine their stability and behavior under crossflow conditions. The results show a clear dependence of the spray propagation on crossflow velocities. With increasing injection pressure the stability against crossflow is increasing. Furthermore, the injectors show different behavior at the same conditions due to their different nozzle designs.
Welss, Richard, Bornschlegel, Sebastian, Wensing, Michael
Strategies to Define Surrogate Fuels for the Description of the Multicomponent Evaporation Behavior of Hydrocarbon Fuels2018-01-16929/10/2018
The scope of this work is to propose a methodology to define multicomponent surrogate mixtures which describe the main evaporation characteristics of real gasoline fuels. Since real fuels are commonly complex mixtures with hundreds or thousands of hydrocarbons, their exact composition is generally not known. Only global characteristics are standardized. An accurate modeling of such complex mixtures in 3D-CFD requires the definition of a suitable surrogate. So far, surrogate mixtures have mostly been defined based on their combustion properties, such as ignition delay or burning velocity, irrespective of their evaporation characteristics. For this reason, in this work, a systematic study is carried out to develop a methodology to define mixtures of representative components that mimic the evaporation behavior of real fuels. Specifically, the following aspects are analyzed: the necessary number and type of the surrogate components, the definition of optimization targets representing the real fuel properties of interest (i.e. the vapor pressure and the distillation curve), the formulation of an appropriate numerical model to evaluate these quantities and the choice of a suitable optimization algorithm to obtain the optimal surrogate composition. It is shown that these different aspects can influence the surrogate definition, potentially leading to a non-optimal representation of the real fuel target properties. This investigation is carried out for four representative real fuels, for which experimental data on their vapor pressure and distillation curve are available. Finally, suitable surrogates are proposed for all fuels.
Pati, Andrea, Gierth, Sandro, Haspel, Philip, Hasse, Christian, Munier, Jerome
Combustion Characteristics of PRF and TSF Ethanol Blends with RON 98 in an Instrumented CFR Engine2018-01-16729/10/2018
The CFR F1 engine is the standard testing apparatus used for rating the research octane number (RON) of gasoline fuels. Unlike the motor octane number (MON) method, where the intake port temperature after the carburetor is controlled by an electric heater, the mixture temperature can vary during the RON test due to the heat of vaporization (HoV) of the fuel. Ethanol is receiving increasing attention as a high octane and high HoV fuel component. This work presents an analysis of the combustion characteristics during the RON rating of ethanol fuel blends according to the standard ASTM D2699 method, highlighting the effects of ethanol concentration and base fuel composition. All fuels were blended to a constant RON of 98. Ethanol levels varied from 0 to 50 vol% and the base fuels were surrogate blends composed of primary reference fuels (PRF), toluene standardization fuels (TSF), and a four component gasoline surrogate. These were compared against two full boiling range gasolines, also having a RON of 98. Through the use of detailed cylinder pressure analyses, this paper provides insights into the combustion behavior of various RON 98 fuels which are commonly not captured by the standard RON knock rating method. Ethanol was found to significantly reduce the pressure transducer based knock intensity of PRF fuel blends up to a level of 30 vol%, despite all fuels having the same RON. Meanwhile, the knock intensity of the equivalent TSF fuel blends was found to be relatively insensitive to ethanol concentration. For ethanol concentrations beyond 30 vol%, the pressure transducer based knock intensity behavior did not appear to be affected by the base fuel composition.
Hoth, Alexander, Kolodziej, Christopher P., Rockstroh, Toby, Wallner, Thomas
Fuel Stratification Using Twin-Tumble Intake Flows to Extend Lean Limit in Super-Lean Gasoline Combustion2018-01-16649/10/2018
To drastically improve thermal efficiency of a gasoline spark-ignited engine, super-lean burn is a promising solution. Although, studies of lean burn have been made by so many researchers, the realization is blocked by a cycle-to-cycle combustion variation. In this study, based on the causes of cycle-to-cycle variation clarified by the authors’ previous study, a unique method to reduce the cycle-to-cycle variation is proposed and evaluated. That is, a bulk quench at early expansion stroke could be reduced by making slight fuel stratification inside the cylinder using the twin-tumble of intake flows. As a result, the lean limit was extended with keeping low NOx and moderate THC emissions, leading to higher thermal efficiency.
Moriyoshi, Yasuo, Kuboyama, Tatsuya, Kaneko, Makoto, Yamada, Toshio, Sato, Hironao
Simulation of the Effect of Intake Pressure and Split Injection on Lean Combustion Characteristics of a Poppet-Valve Two-Stroke Direct Injection Gasoline Engine at High Loads2018-01-17239/10/2018
Poppet-valve two-stroke gasoline engines can increase the specific power of their four-stroke counterparts with the same displacement and hence decrease fuel consumption. However, knock may occur at high loads. Therefore, the combustion with stratified lean mixture was proposed to decrease knock tendency and improve combustion stability in a poppet-valve two-stroke direct injection gasoline engine. The effect of intake pressure and split injection on fuel distribution, combustion and knock intensity in lean mixture conditions at high loads was simulated with a three-dimensional computational fluid dynamic software. Simulation results show that with the increase of intake pressure, the average fuel-air equivalent ratio in the cylinder decreases when the second injection ratio was fixed at 70% at a given amount of fuel in a cycle. With the increase of intake pressure, ignition timing advances, combustion duration slightly decreases first and then increases while the maximum pressure rise rate first increases and then drops. High intake pressure can prevent the occurrence of knock through decreased fuel-air equivalent ratio around the cylinder. The second injection timing can also influence combustion processes. The improved indicated thermal efficiency occurs when the second injection timing is 90°CA after top dead center. Delayed second injection timing is beneficial for the development of initial flame kernel. But when the second injection timing is 60°CA after top dead center, the fuel is only consumed by flame propagation. When auto-ignition occurs in the end mixture, the heat released by auto-ignition gradually increases with the delay of the second injection timing. Meanwhile, indicated thermal efficiency is increased when little amount of end mixture auto-ignites without knock.
Li, Xiao, He, Bang-Quan, Zhao, Hua, Zhang, Yan, Li, Yufeng, Bai, Honglin
Effectiveness of Fuel Enrichment on Knock Suppression in a Gasoline Spark-Ignited Engine2018-01-16659/10/2018
Knock, and more recently, super-knock, have been limiting factors on improving engine efficiency. As a result, engines often operate rich at high loads to avoid damage resulting from knock and protect the after-treatment system from excessive thermal stress. In this work, port-fuel injection and direct injection of excess fuel is explored as a mechanism to suppress knock and super-knock. Under naturally aspirated conditions, increasing the fuel enrichment initially increases knock intensity. However, further increasing fuel enrichment subsequently decreases knock intensity. The competing mechanism from calorific value and latent heat of vaporization can be used to explain the phenomenon. However, when directly injecting the excess fuel after the spark plug has been fired, knock intensity monotonically decreases with increasing fuel quantity. This decrease is shown to be due to fuel quenching the flame that is propagating from spark location. Under boosted conditions, the amount of fuel injected is of critical importance in avoiding super-knock. A lower fuel quantity leads to knock suppression. But beyond a critical value, higher quantities of fuel result in more interaction with the oil film on the cylinder liner, leading to a greater number of pre-ignition precursors (fuel + oil droplets) and a higher number of pre-ignition events. These spontaneous pre-ignition events arising from fuel enrichment are further advanced and do not lead to super-knock behavior due to high amounts of charge cooling from evaporation of the excess fuel. Furthermore, such spontaneous pre-ignition events are characterized by higher pressure in the intake stroke and dominance of higher frequency oscillations in the cylinder.
Singh, Eshan, Dibble, Robert
Laminar Burning Velocity of Market Type Gasoline Surrogates as a Performance Indicator in Internal Combustion Engines2018-01-16679/10/2018
The laminar burning velocity is an important parameter in various combustion models for engine simulations. With respect to computational time for computational fluid dynamics (CFD) and full system engine simulations, the calculation of laminar burning velocities using a detailed chemical mechanism can be replaced by incorporation of approximation formulas, based on rate-ratio asymptotics. In the present study, a work flow is developed to analyze the engine efficiency performance of spark ignition engines with respect to the laminar burning velocity as a fundamental fuel property. Firstly, methane is used as a fuel to assess practicability of the approach. The procedure is subsequently adopted for market type gasoline surrogates, RON95 and RON100. Detailed chemistry calculations are carried out for the three target fuels using existing state of the art mechanisms, the Aramco [Zhou et al., Proc. Combust. Inst., pp. 403-411, 2017] and the ITV RWTH mechanism [Cai et al., Combust. Flame, pp. 1623-1637, 2015]. Subsequently, the asymptotic-based approximation formula by Göttgens et al. [Göttgens et al., Symp. (Intl.) Combust., pp. 129-135, 1992] is employed and fitted based on detailed simulations under engine relevant conditions. In order to compute fundamental engine performance parameters, such as the indicated mean effective pressures (IMEP), the deduced model is embedded in GT-POWER [Gamma Technologies, LCC.,“GT-SUITE”, 2018], an industry standard tool for engine simulations. Significant differences in IMEP can be observed between calculations with the newly incorporated model and the default model for the laminar burning velocity of methane/air mixtures. Higher burning velocities were found to decrease the burn duration. In order to optimize thermal efficiency, the center of combustion must be delayed by shifting spark timing. For gasoline surrogates, differences in IMEP and efficiency between the two flame speed models were found to be less pronounced. This implies that either the GT-POWER inbuilt flame speed model for gasoline is reasonably good or sensitivities to the laminar burning velocity might not be represented well by the code.
Hesse, Raik, Beeckmann, Joachim, Wantz, Kevin, Pitsch, Heinz
Severe Soot Oxidations in Gasoline Particulate Filter Applications2018-01-16999/10/2018
With the start of EU6 in 2017 gasoline particulate filters (GPF) have been introduced to production vehicles. It is expected that by 2019 all gasoline direct injection engines sold in Europe will be equipped with a GPF. A similar trend is observed in China with a slight delay compared to Europe, but covering all gasoline engines, including those with port fuel injection technology. With the introduction of GPFs, new requirements are introduced to the management of gasoline engines and their aftertreatment. One requirement is to protect the aftertreatment components from excessive temperatures and damage as result of uncontrolled soot oxidations. While the general fundamentals are similar to those in diesel applications, significant differences exist in the relevant details. In gasoline applications, for example, one of the worst case scenarios with respect to severe soot oxidations is a fuel cutoff during which oxygen is introduced, whereas the drop to idle, critical in diesel applications, is not of concern. In this contribution, we will evaluate the sensitivity of the soot oxidation in gasoline particulate filters to various operating parameters. We will discuss results obtained by a combination of a broad set of data from fuel cutoff experiments performed on engine bench under different operating conditions as well as detailed numerical simulations. Different limiting cases and regimes as well as simplified methods to describe them will be introduced and discussed. The results will be relevant for developing software functionalities to manage the soot, to protect the filter component as well as for calibrations.
Boger, Thorsten, Rose, Dominik, Nicolin, Per, Coulet, Bertrand, Bachurina, Anastasiia
Critical Analysis of PM Index and Other Fuel Indices: Impact of Gasoline Fuel Volatility and Chemical Composition2018-01-17419/10/2018
Among the challenges for the future facing the development of gasoline engines, one of the most important is the reduction of particles emissions. This study proposes a critical and objective evaluation of the influence of fuel characteristics on gasoline particles emission through the use of Fuel Particle Indices. For this, a selected fuel matrix composed of 22 fuels was built presenting different volatility and chemical composition (content in total aromatics, heavy cuts and ethanol). To represent the fuel sooting tendency, seven Fuel Particle Indices were selected based on a literature review, namely, Particulate Matter Index (PMI), Particulate Number index (PNI), Threshold Sooting index (TSI), Smoke point (SP), Oxygen Extended Sooting Index (OESI), Simplified index 1 and 2 (sPMI 1, sPMI 2). These indices were computed on the fuel matrix and compared on the basis of three main axes. First, the sensitivity to fuel variation. Second, the agreement with engine particles emissions measured on vehicle on three vehicles. Third, the ease to compute with respect to the data availability in the European standard EN228. The comparison of fuel particles indices revealed different sensitivities to fuel variation: PMI, sPMI 1 and sPMI 2 represent well the effects of heavy aromatics, PNI is highly sensitive to the DVPE whereas SP, OESI and TSI were found well representative of the total aromatic content but represent weakly the effect of heavy aromatics. The comparison of the fuel particles indices with engine data indicates a good agreement of all indices, except for PNI. Finally, sPMI 1, sPMI 2 and calculated SP were found to be much easier to compute because they need simple data as input. This work highlights the importance of fuel quality on the reduction of particles emissions and suggests relevant Fuel Particles Indices that allow to capture fuel variation.
Ben Amara, Arij, Tahtouh, Toni, Ubrich, Elisabeth, Starck, Laurie, Moriya, Hidenori, IIda, Yutaka, KOJI, Nagata
New GKI - Gasoline Knock Index for Rating of Fuel’s Knock Resistance on an Upgraded CFR Test Engine2018-01-17439/10/2018
In terms of international efforts for conservation of resources and reducing CO2-emission, the thermal efficiency of SI engines needs to be increased. One key enabler to achieve this goal is the availability of highly knock-resistant fuels: it allows to break up the trade-off between elevated compression ratio demanded for high part-load efficiency and a reduced knock tendency at high engine loads by a minimized requirement for adverse spark retard. In view of the world’s fuel map, which is dominated nowadays by qualities between 91 and 98 RON, there is a beginning transition towards increased knock resistance (above 100 RON) being observed in several countries. The corresponding standards for engine-based fuel quality rating provide a RON scale covering the range from 40 to 120.3, which basically seems to be enough. At a second glance the change in reference material from isooctane/n-heptane mixtures towards isooctane with TEL for RON > 100 changes the rating behavior of the method. Comprehensive research and development has been established considering the test engine operation mode as well as the data processing, conclusively defining an improved test method as a suggestion for future knock resistance rating. In order to increase transferability of the fuel’s quality number to modern engines, especially in view to RDE legislation, the operation mode is basically characterized by a stoichiometric mixture composition in combination with a closed-loop control of the combustion phasing. The CR achievable at predefined knock intensity, statistically assessed by a 95% cumulative frequency of knock pressure amplitudes, defines knock resistance without relevant limitations in scale expressed by the new fuel characteristic GKI - Gasoline Knock Index.
Hauber, Johann, Huber, Karl, Nell, Robert
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