John B. Heywood
Bio: John B. Heywood is an academic researcher. The author has contributed to research in topics: Gasoline & Combustion chamber. The author has an hindex of 1, co-authored 1 publications receiving 14157 citations.
01 Jan 1988
TL;DR: In this article, the authors describe real engine flow and combustion processes, as well as engine operating characteristics and their operation, including engine design and operating parameters, engine characteristics, and operating characteristics.
Abstract: 1 Engine Types and Their Operations 2 Engine Design and Operating Parameters 3 Thermochemistry of Fuel-Air Mixtures 4 Properties of Working Fluids 5 Ideal Models of Engine Cycles 6 Gas Exchange Processes 7 SI Engine Fuel Metering and Manifold Phenomena 8 Charge Motion within the Cylinder 9 Combustion in Ignition Engines 10 Combustion in Compression Ignition Engines 11 Pollutant Formation and Control 12 Engine Heat Transfer 13 Engine Friction and Lubrication 14 Modeling Real Engine Flow and Combustion Processes 15 Engine Operating Characteristics Appendixes
TL;DR: A novel parameter automation strategy for the particle swarm algorithm and two further extensions to improve its performance after a predefined number of generations to overcome the difficulties of selecting an appropriate mutation step size for different problems.
Abstract: This paper introduces a novel parameter automation strategy for the particle swarm algorithm and two further extensions to improve its performance after a predefined number of generations. Initially, to efficiently control the local search and convergence to the global optimum solution, time-varying acceleration coefficients (TVAC) are introduced in addition to the time-varying inertia weight factor in particle swarm optimization (PSO). From the basis of TVAC, two new strategies are discussed to improve the performance of the PSO. First, the concept of "mutation" is introduced to the particle swarm optimization along with TVAC (MPSO-TVAC), by adding a small perturbation to a randomly selected modulus of the velocity vector of a random particle by predefined probability. Second, we introduce a novel particle swarm concept "self-organizing hierarchical particle swarm optimizer with TVAC (HPSO-TVAC)". Under this method, only the "social" part and the "cognitive" part of the particle swarm strategy are considered to estimate the new velocity of each particle and particles are reinitialized whenever they are stagnated in the search space. In addition, to overcome the difficulties of selecting an appropriate mutation step size for different problems, a time-varying mutation step size was introduced. Further, for most of the benchmarks, mutation probability is found to be insensitive to the performance of MPSO-TVAC method. On the other hand, the effect of reinitialization velocity on the performance of HPSO-TVAC method is also observed. Time-varying reinitialization step size is found to be an efficient parameter optimization strategy for HPSO-TVAC method. The HPSO-TVAC strategy outperformed all the methods considered in this investigation for most of the functions. Furthermore, it has also been observed that both the MPSO and HPSO strategies perform poorly when the acceleration coefficients are fixed at two.
TL;DR: In this paper, the status of fat and oil derived diesel fuels with respect to fuel properties, engine performance, and emissions is reviewed, and it is concluded that the price of the feedstock fat or oil is the major factor determining biodiesel price.
Abstract: In this article, the status of fat and oil derived diesel fuels with respect to fuel properties, engine performance, and emissions is reviewed The fuels considered are primarily the methyl esters of fatty acids derived from a variety of vegetable oils and animal fats, and referred to as biodiesel The major obstacle to widespread use of biodiesel is the high cost relative to petroleum Economics of biodiesel production are discussed, and it is concluded that the price of the feedstock fat or oil is the major factor determining biodiesel priceBiodiesel is completely miscible with petroleum diesel fuel, and is generally tested as a blend The use of biodiesel in neat or blended form has no effect on the energy based engine fuel economy The lubricity of these fuels is superior to conventional diesel, and this property is imparted to blends at levels above 20 vol% Emissions of PM can be reduced dramatically through use of biodiesel in engines that are not high lube oil emitters Emissions of NOx increase significantly for both neat and blended fuels in both two- and four-stroke engines The increase may be lower in newer, lower NOx emitting four-strokes, but additional data are needed to confirm this conclusion A discussion of available data on unregulated air toxins is presented, and it is concluded that definitive studies have yet to be performed in this area A detailed discussion of important biodiesel properties and recommendations for future research is presented Among the most important recommendations is the need for all future studies to employ biodiesel of well-known composition and purity, and to report detailed analyses The purity levels necessary for achieving adequate engine endurance, compatibility with coatings and elastomers, cold flow properties, stability, and emissions performance must be better defined
TL;DR: In this article, the RNG κ-e turbulence model derived by Yakhot and Orszag (1986) based on the Renormalization Group theory has been modified and applied to variable-density engine flows in the present study.
Abstract: The RNG κ-e turbulence model derived by Yakhot and Orszag (1986) based on the Renormalization Group theory has been modified and applied to variable-density engine flows in the present study. The original RNG-based turbulence transport approximations were developed formally for an incompressible flow. In order to account for flow compressibility the RNG e-equation is modified and closed through an isotropic rapid distortion analysis. Computations were made of engine compressing/expanding flows and the results were compared with available experimental observations in a production diesel engine geometry. The modified RNG κ-e model was also applied to diesel spray combustion computations. It is shown that the use of the RNG model is warranted for spray combustion modeling since the ratio of the turbulent to mean-strain time scales is appreciable due to spray-generated mean flow gradients, and the model introduces a term to account for these effects. Large scale flow structures are predicted which ar...
TL;DR: In this paper, a phenomenological description of how direct-injection (DI) diesel combustion occurs has been derived from laser-sheet imaging and other recent optical data, which is summarized in a series of idealized schematics that depict the combustion process for a typical, modern-diesel-engine condition.
Abstract: A phenomenological description, or “conceptual model,” of how direct-injection (DI) diesel combustion occurs has been derived from laser-sheet imaging and other recent optical data. To provide background, the most relevant of the recent imaging data of the author and co-workers are presented and discussed, as are the relationships between the various imaging measurements. Where appropriate, other supporting data from the literature is also discussed. Then, this combined information is summarized in a series of idealized schematics that depict the combustion process for a typical, modern-diesel-engine condition. The schematics incorporate virtually all of the information provided by our recent imaging data including: liquidand vapor-fuel zones, fuel/air mixing, autoignition, reaction zones, and soot distributions. By combining all these elements, the schematics show the evolution of a reacting diesel fuel jet from the start of fuel injection up through the first part of the mixing-controlled burn (i.e. until the end of fuel injection). In addition, for a “developed” reacting diesel fuel jet during the mixingcontrolled burn, the schematics explain the sequence of events that occurs as fuel moves from the injector downstream through the mixing, combustion, and emissions-formation processes. The conceptual model depicted in these schematics also gives insight into the most likely mechanisms for soot formation and destruction and NO formation during the portion of the DI diesel combustion event discussed.
TL;DR: In this paper, five types of models applied to HCCI engine modelling are discussed in the present paper, and specific strategies for diesel-fuelled, gasoline-fined, and other alternative fuelled combustion are also discussed.
Abstract: HCCI combustion has been drawing the considerable attention due to high efficiency and lower nitrogen oxide (NOx) and particulate matter (PM) emissions. However, there are still tough challenges in the successful operation of HCCI engines, such as controlling the combustion phasing, extending the operating range, and high unburned hydrocarbon and CO emissions. Massive research throughout the world has led to great progress in the control of HCCI combustion. The first thing paid attention to is that a great deal of fundamental theoretical research has been carried out. First, numerical simulation has become a good observation and a powerful tool to investigate HCCI and to develop control strategies for HCCI because of its greater flexibility and lower cost compared with engine experiments. Five types of models applied to HCCI engine modelling are discussed in the present paper. Second, HCCI can be applied to a variety of fuel types. Combustion phasing and operation range can be controlled by the modification of fuel characteristics. Third, it has been realized that advanced control strategies of fuel/air mixture are more important than simple homogeneous charge in the process of the controlling of HCCI combustion processes. The stratification strategy has the potential to extend the HCCI operation range to higher loads, and low temperature combustion (LTC) diluted by exhaust gas recirculation (EGR) has the potential to extend the operation range to high loads; even to full loads, for diesel engines. Fourth, optical diagnostics has been applied widely to reveal in-cylinder combustion processes. In addition, the key to diesel-fuelled HCCI combustion control is mixture preparation, while EGR is the main path to achieve gasoline-fuelled HCCI combustion. Specific strategies for diesel-fuelled, gasoline-fuelled and other alternative fuelled HCCI combustion are also discussed in the present paper.