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Foster, David E.
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Optimization of Heat Release Shape and the Connecting Rod Crank Radius Ratio for Low Engine Noise and High Thermal Efficiency of Premixed Diesel Engine Combustion

Hokkaido Univ.-Gen Shibata, Koki Ishi, Yushi Shibaike, Hideyuki Ogawa
Subaru Motors-Hirooki Ushijima
Published 2015-04-14 by SAE International in United States
Premixed diesel combustion offers the potential of high thermal efficiency and low emissions, however, because the rapid rate of pressure rise and short combustion durations are often associated with low temperature combustion processes, noise is also an issue. The reduction of combustion noise is a technical matter that needs separate attention. Engine noise research has been conducted experimentally with a premixed diesel engine and techniques for engine noise simulation have been developed. The engine employed in the research here is a supercharged, single cylinder DI diesel research engine with a high pressure common rail fuel injection system. In the experiments, the engine was operated at 1600 rpm and 2000 rpm, the engine noise was sampled by two microphones, and the sampled engine noise was averaged and analyzed by an FFT sound analyzer. The structural attenuation of the test engine was calculated from the power spectrum of the FFT analysis of the in-cylinder pressure wave data and the cross power spectrum of the sound pressure of the engine noise by the coherence method. With the heat…
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Experimental and Computational Assessment of Inlet Swirl Effects on a Gasoline Compression Ignition (GCI) Light-Duty Diesel Engine

Univ. of Wisconsin-Paul Loeper, Youngchul Ra, David E. Foster, Jaal Ghandhi
Published 2014-04-01 by SAE International in United States
The light-medium load operating regime (4-8 bar net IMEP) presents many challenges for advanced low temperature combustion strategies (e.g. HCCI, PPC) in light-duty, high speed engines. In this operating regime, lean global equivalence ratios (Φ<0.4) present challenges with respect to autoignition of gasoline-like fuels. Considering this intake temperature sensitivity, the objective of this work was to investigate, both experimentally and computationally, gasoline compression ignition (GCI) combustion operating sensitivity to inlet swirl ratio (Rs) variations when using a single fuel (87-octane gasoline) in a 0.475-liter single-cylinder engine based on a production GM 1.9-liter high speed diesel engine.For the first part of this investigation, an experimental matrix was developed to determine how changing inlet swirl affected GCI operation at various fixed load and engine speed operating conditions (4 and 8 bar net IMEP; 1300 and 2000 RPM). Here, experimental results showed significant changes in CA50 due to changes in inlet swirl ratio. For example, at the 4 bar net IMEP operating condition at 1300 RPM, a reduction in swirl ratio (from 2.2 to 1.5) caused a 6…
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Experimental Investigation of Transient Response and Turbocharger Coupling for High and Low Pressure EGR Systems

SAE International Journal of Engines

University of Wisconsin-David Heuwetter, William Glewen, David E. Foster, Roger Krieger, Michael Andrie
  • Journal Article
  • 2014-01-1367
Published 2014-04-01 by SAE International in United States
The transient response of an engine with both High Pressure (HP) and Low Pressure (LP) EGR loops was compared by conducting step changes in EGR fraction at a constant engine speed and load. The HP EGR loop performance was shown to be closely linked to turbocharger performance, whereas the LP EGR loop was relatively independent of turbocharger performance and vice versa. The same experiment was repeated with the variable geometry turbine vanes completely open to reduce turbocharger action and achieve similar EGR rate changes with the HP and LP EGR loops. Under these conditions, the increased loop volume of the LP EGR loop prolonged the response of intake O2 concentration following the change in air-fuel ratio. The prolonged change of intake O2 concentration caused emissions to require more time to reach steady state as well. Strong coupling between the HP EGR loop and turbochargers was again observed using a hybrid EGR strategy. The potential benefit of the HP EGR loop's smaller volume and shorter residence time was largely negated by the simultaneous use of the…
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Experimental Investigation of Light-Medium Load Operating Sensitivity in a Gasoline Compression Ignition (GCI) Light-Duty Diesel Engine

General Motors Company-Russ Durrett
Univ. of Wisconsin Madison-Paul Loeper, Youngchul Ra, Cory Adams, David E. Foster, Jaal Ghandhi, Michael Andrie, Roger Krieger
Published 2013-04-08 by SAE International in United States
The light-medium load operating range (4-7 bar net IMEP) presents many challenges for advanced low temperature combustion strategies utilizing low cetane fuels (specifically, 87-octane gasoline) in light-duty, high-speed engines. The overly lean overall air-fuel ratio (Φ≺0.4) sometimes requires unrealistically high inlet temperatures and/or high inlet boost conditions to initiate autoignition at engine speeds in excess of 1500 RPM. The objective of this work is to identify and quantify the effects of variation in input parameters on overall engine operation. Input parameters including inlet temperature, inlet pressure, injection timing/duration, injection pressure, and engine speed were varied in a ~0.5L single-cylinder engine based on a production General Motors 1.9L 4-cylinder high-speed diesel engine.With constraints of combustion efficiency, noise level (pressure rise rate) and emissions, engine operation sensitivity due to changes in inlet temperature between 50-90C was first examined for fixed fueling rates. This experiment was then repeated at different inlet pressures and engine speeds. Finally, constant load experiments were performed in which perturbations in injection strategies (timing, duration, and pressure) were executed to assess overall system sensitivity.…
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Characterization of Particulate Morphology, Nanostructures, and Sizes in Low-Temperature Combustion with Biofuels

Argonne National Laboratory-HeeJe Seong, Kyeong O. Lee, Seungmok Choi
University of Wisconsin at Madison-Cory Adams, David E. Foster
Published 2012-04-16 by SAE International in United States
Detailed characteristics of morphology, nanostructures, and sizes were analyzed for particulate matter (PM) emissions from low-temperature combustion (LTC) modes of a single-cylinder, light-duty diesel engine. The LTC engines have been widely studied in an effort to achieve high combustion efficiency and low exhaust emissions. Recent reports indicate that the number of nucleation mode particles increased in a broad engine operating range, which implies a negative impact on future PM emissions regulations in terms of the nanoparticle number. However, the size measurement of solid carbon particles by commercial instruments is indeed controversial due to the contribution of volatile organics to small nanoparticles. In this work, an LTC engine was operated with various biofuel blends, such as blends (B20) of soy bean oil (soy methyl ester, SME20) and palm oil (palm methyl ester, PME20), as well as an ultra-low-sulfur diesel fuel. Injection timing was varied at 22°, 26°, and 30° before top dead center for each fuel. A commercial scanning mobility particle sizer (SMPS) was used to measure the particle number size distributions. Also, a unique thermophoretic…
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Analysis of Deviations from Steady State Performance During Transient Operation of a Light Duty Diesel Engine

SAE International Journal of Engines

University of Wisconsin-William Glewen, David Heuwetter, David E. Foster, Michael Andrie, Roger Krieger
  • Journal Article
  • 2012-01-1067
Published 2012-04-16 by SAE International in United States
Deviations between transient and steady state operation of a modern light duty diesel engine were identified by comparing rapid load transitions to steady state tests at the same speeds and fueling rates. The validity of approximating transient performance by matching the transient charge air flow rate and intake manifold pressure at steady state was also assessed. Results indicate that for low load operation with low temperature combustion strategies, transient deviations of MAF and MAP from steady state values are small in magnitude or short in duration and have relatively little effect on transient engine performance. A new approximation accounting for variations in intake temperature and excess oxygen content of the EGR was more effective at capturing transient emissions trends, but significant differences in magnitudes remained in certain cases indicating that additional sources of variation between transient and steady state performance remain unaccounted for.
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Gasoline DICI Engine Operation in the LTC Regime Using Triple- Pulse Injection

SAE International Journal of Engines

General Motors Company-Russ Durrett
University of Wisconsin-Madison-Youngchul Ra, Paul Loeper, Michael Andrie, Roger Krieger, David E. Foster, Rolf D. Reitz
  • Journal Article
  • 2012-01-1131
Published 2012-04-16 by SAE International in United States
An investigation of high speed direct injection (DI) compression ignition (CI) engine combustion fueled with gasoline injected using a triple-pulse strategy in the low temperature combustion (LTC) regime is presented. This work aims to extend the operation ranges for a light-duty diesel engine, operating on gasoline, that have been identified in previous work via extended controllability of the injection process. The single-cylinder engine (SCE) was operated at full load (16 bar IMEP, 2500 rev/min) and computational simulations of the in-cylinder processes were performed using a multi-dimensional CFD code, KIVA-ERC-Chemkin, that features improved sub-models and the Chemkin library. The oxidation chemistry of the fuel was calculated using a reduced mechanism for primary reference fuel combustion chosen to match ignition characteristics of the gasoline fuel used for the SCE experiments.With constraints on a minimum allowable combustion efficiency, maximum allowable noise level (pressure rise rate) and maximum allowable NOx and soot emissions, engine operation ranges were identified as functions of injection timings and the fuel split ratio (i.e., fraction of total fuel injected in each pulse) with triple-pulse…
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Thermodynamic Benefits of Opposed-Piston Two-Stroke Engines

Achates Power, Inc.-Randy E. Herold, Michael H. Wahl, Gerhard Regner, James U. Lemke
Univ. of Wisconsin - Madison-David E. Foster
Published 2011-09-13 by SAE International in United States
A detailed thermodynamic analysis was performed to demonstrate the fundamental efficiency advantage of an opposed-piston two-stroke engine over a standard four-stroke engine. Three engine configurations were considered: a baseline six-cylinder four-stroke engine, a hypothetical three-cylinder opposed-piston four-stroke engine, and a three-cylinder opposed-piston two-stroke engine. The bore and stroke per piston were held constant for all engine configurations to minimize any potential differences in friction. The closed-cycle performance of the engine configurations were compared using a custom analysis tool that allowed the sources of thermal efficiency differences to be identified and quantified. The simulation results showed that combining the opposed-piston architecture with the two-stroke cycle increased the indicated thermal efficiency through a combination of three effects: reduced heat transfer because the opposed-piston architecture creates a more favorable combustion chamber area/volume ratio, increased ratio of specific heats because of leaner operating conditions made possible by the two-stroke cycle, and decreased combustion duration achievable at the fixed maximum pressure rise rate because of the lower energy release density of the two-stroke engine. When averaged over a representative engine…
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Effects of Low Pressure EGR on Transient Air System Performance and Emissions for Low Temperature Diesel Combustion

University of Wisconsin-David Heuwetter, William Glewen, Christopher Meyer, David E. Foster, Michael Andrie, Roger Krieger
Published 2011-09-11 by SAE International in United States
Low pressure EGR offers greater effectiveness and flexibility for turbocharging and improved heat transfer compared to high pressure EGR systems. These characteristics have been shown to provide potential for further NOx, soot, and fuel consumption reductions in modern diesel engines. One of the drawbacks is reduced transient response capability due to the long EGR path. This can be largely mitigated by combining low pressure and high pressure loops in a hybrid EGR system, but the changes in transient response must be considered in the design of an effective control strategy.The effect of low pressure EGR on transient emissions was evaluated using two different combustion strategies over a variety of transient events. Low pressure EGR was found to significantly lengthen the response time of intake oxygen concentration following a transient event, which can have a substantial effect on emissions formation. The difference in response time between the two EGR systems has important implications for prediction of transient emissions based on steady state mode points since the correlation between transient and steady state emissions may change substantially…
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Particulate Matter Sampling and Volatile Organic Compound Removal for Characterization of Spark Ignited Direct Injection Engine Emissions

SAE International Journal of Fuels and Lubricants

General Motors LLC-Paul Najt, Kushal Narayanaswamy, Arun Solomon
Pacific Northwest National Laboratory-Alla Zelenyuk
  • Journal Article
  • 2011-01-2100
Published 2011-08-30 by SAE International in United States
More stringent emissions regulations are continually being proposed to mitigate adverse human health and environmental impacts of internal combustion engines. With that in mind, it has been proposed that vehicular particulate matter (PM) emissions should be regulated based on particle number in addition to particle mass. One aspect of this project is to study different sample handling methods for number-based aerosol measurements, specifically, two different methods for removing volatile organic compounds (VOCs). One method is a thermodenuder (TD) and the other is an evaporative chamber/diluter (EvCh). These sample-handling methods have been implemented in an engine test cell with a spark-ignited direct injection (SIDI) engine. The engine was designed for stoichiometric, homogeneous combustion. SIDI is of particular interest for improved fuel efficiency compared to other SI engines, however, the efficiency benefit comes with greater PM emissions and may therefore be subject to the proposed number-based PM regulation. Another aspect of this project is to characterize PM from this engine in terms of particle number and composition.PM number distributions were acquired using a TSI Scanning Mobility Particle…
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