In Figure 11, contour plots of Burned Gas mass fraction are shown for different time instants on the plane XZ. The figure shows the swirl flow induced by the intake ports and the presence of some residuals in the piston cup at the end of the scavenging process. The scavenging characteristics are quantified by evaluating three global parameters, namely the delivery ratio, the trapping efficiency and the charging efficiency [5].
The use of air as a scavenging fluid is a common choice. Unfortunately, a certain amount of air flows away through the exhaust valves and this increases the work for pumping due to the amount of air which is lost. For this reason, the inlet mass flow rate is generally higher than the amount of air theoretically required to scavenge the cylinder.
Indeed, the delivery ratio is commonly in a range between 1. Energies , 14, 10 of 19 Figure Contour plot of the Burned Gas mass fraction at several instants on the plane XY. Figure Contour plot of the Burned Gas mass fraction at several instants on the plane XZ. Energies , 14, 11 of 19 The scavenging process under theoretical conditions can be described by two simpli- fied models [13]. On one side, the perfect displacement model considers that the burned gases are pushed out by the fresh air without any mixing between them.
On the other hand, the perfect mixing assumes that the incoming fresh air mixes instantaneously and uni- formly with the gas mixture already in the cylinder.
As a matter of fact, the real scavenging process will be in between such models and will differ from both. For the baseline case, the delivery ratio is equal to 1. These efficiencies are close to those corresponding to a perfect mixing condition. Influence of Inlet Mass Flow Rate Several simulations have been performed by varying the inlet mass-flow rate, G, from 0.
Figure 12a shows the mass flow rate of Fresh Air through the intake ports as a function of time for the different cases. The flow rate is assumed to be negative for fresh air entering into the cylinder, otherwise it is assumed to be positive. As expected, by increasing G, the flow rate of fresh air entering into the cylinder increases as well. In Figure 12b, the Burned Gas BG mass fraction profiles are given based on the relationship between the BG mass fraction in the cylinder, along the x-axis, and the BG mass fraction in the exhaust ducts, along the y-axis.
The figure shows the short-circuiting phenomenon for different inlet mass flow rates. Indeed, it can be observed that, with the lower mass flow rates, the Fresh Air enters into the exhaust pipes faster, thus diverging from the perfect displacement condition. The lowest appearance of the short-circuiting phenomenon is observed with 0.
Nevertheless, the higher the intake mass flow rate, the lower the percentage of Burned Gas in the cylinder at the end of the scavenging process. In Figure 12c,d, the trapping and the charging efficiency, respectively, are plotted as a function of the delivery ratio. Each square symbol corresponds to a given inlet mass flow rate.
The figure shows that the delivery ratio increases with the inlet mass flow rate. As expected, the trapping efficiency decreases with increasing delivery ratio, whereas the charging efficiency increases with the delivery ratio. Figure 12e depicts the projection of the velocity field vectors on the XZ middle-height plane of the cylinder. The figure clearly shows the swirl motion that develops into the cylinder as a consequence of the inlet ports angle.
As the inlet mass flow rate increases, higher velocities are obtained, corresponding to a higher swirl ratio in the cylinder. The values of the swirl ratio are given in Table 3. The table shows that, for the baseline mass flow rate Gb , the swirl ratio is about 2, which corresponds to a typical value for this type of engine.
Table 3. Swirl ratio as a function of the inlet flow rate. Scavenging performance for Cylinder 3. Influence of Cylinder Number and Outlet Boundary Conditions A computational analysis has also been performed for Cylinder 1 and Cylinder 5, and the scavenging performances of all the three cylinders are finally compared.
The measured pressure profiles at the outlet sections differ for the three cylinders, as given in Figure The remaining initial and boundary conditions are the same as for the baseline case, as well as the computational mesh.
Energies , 14, 13 of 19 Figure Experimental pressure profiles at the exhaust sections for the three cylinders as a function of CAD.
The mass of Fresh Air trapped into the three cylinders has been computed along with the cylinder total mass, i. At the start of the simulation, as the exhaust valves open, the amount of mass in the cylinder decreases, whereas the Fresh Air is still zero, up to the point that the intake ports open and both the total and the Fresh Air mass in the cylinders increase. Due to the back-flow through intake ports, the increase of fluid mass in the cylinder is slower for Cylinder 1 with respect to the other two cylinders.
Nevertheless, at the end of the scavenging process, the three profiles are very similar to each other. Moreover, some differences are observed in the Burned Gas mass fraction profiles of Figure 14c. Indeed, Cylinder 1 shows a faster appearance of the short-circuiting phenomenon but, at the end of the scavenging process, the BG mass fraction in the exhaust pipes is noticeably higher with respect to the other two cylinders, due to the different profiles of Fresh Air mass flow rate through the intake ports, as reported in Figure 14a.
Cylinder 3 and Cylinder 5 have a similar behavior. The results are given in Figure 14d, thus showing that, at the start of the scavenging process, all the air delivered through the intake ports is trapped within the cylinder, then the trapping efficiency decreases during the scavenging. At the end of the process, the final delivery ratio is higher for Cylinder 5, meaning that a higher amount of air is flowed through the intake ports with respect to Cylinder 3 and, even more, to Cylinder 1.
However, the trapping efficiency is higher for Cylinder 1 with respect to Cylinder 3 and, even more, to Cylinder 5, thus showing that the scavenging process is more efficient for Cylinder 1. The trapping and charging efficiencies are given as a function of delivery ratio in Figure 14e,f, respectively. The figures show that the efficiency of Cylinder 5 is lower than that of the other two cases. Besides, the percentage of Fresh Air trapped with respect to the in-cylinder total mass, given in Table 4 for the baseline inlet mass flow rate, is lower for Cylinder 5 and higher for Cylinder 3.
The results are given in Figure 15a,b. Slight differences are now obtained for the three cylinders. Cylinder 3, which is in the mid-located, is the most favorable to reach higher efficiencies for all cases, whereas the Cylinder 5 location is the worst one with higher delivery ratios. It can be concluded that the exhaust pressure profile plays a major role in the scaveng- ing outcome of the three cylinders, in agreement with the scientific literature [10], whereas the cylinders position has a minor effect on the scavenging efficiencies.
Negligible differences are expected by comparing the results obtained with the left and right banks, since the bank geometries are very similar. In order to confirm this issue, the scavenging performances of Cylinder 3, belonging to the right bank, and of Cylinder 4, being the corresponding mid-way cylinder of the left bank, have been compared.
The simulation of Cylinder 4 has been performed by using the same initial and boundary conditions of the baseline case, in order to investigate only the role of the different locations. The results are given in Figure 16 in terms of trapping and charging efficiencies versus delivery ratio.
Negligible differences between Cylinder 3 and Cylinder 4 performances are obtained. Table 4. Cylinder 1 Cylinder 3 Cylinder 5 Scavenging performances of the GF56 right bank. Energies , 14, 15 of 19 Figure Influence of cylinders location in the bank on scavenging performances.
Scavenging performances of right and left banks of GF Influence of the Intake Ports Geometry In order to increase the tangential velocity of Fresh Air flow through the intake ports, a geometry modification of such ports is proposed. This choice enables to increase the swirl ratio, in agreement with the scientific literature [9], but keeping nearly constant the delivery ratio with respect to the previous geometry.
The contour plot of the Burned Gas mass fraction is shown in Figure 18 at different time instants. By comparing these results with those obtained with the initial configuration, given in Figure 10, a partially unscanveged zone can be observed close to the cylinder axis, whereas burned gas is not found near the liner throughout the whole scavenging process.
This is the result of the increase of the swirl motion, which helps to scavenge the regions near the cylinder walls at the expense of the central region of the chamber. It is worth noting that the volume enclosed in the near-axis zone of a cylinder is much smaller than the volume enclosed in the near-liner region of the same cylinder. Trapping and charging efficiencies as a function of the delivery ratio are given in Figure 19b,c, respectively.
The results show that the delivery ratio only slightly decreases with the new configuration with respect to the previous one. Both the trapping and the charging efficiencies improve with the new geometry and with delivery ratios higher than 1. Schematic of the new geometry for the intake ports. Contour plot of the Burned Gas mass fraction at different time instants for the new geometry. Energies , 14, 17 of 19 Figure New geometry scavenging performance.
This is due to the different velocity field obtained with the new intake ports geometry, as shown in Figure 19d. With the new configuration, the in-cylinder tangential velocity noticeably increases, leading to a substantial increase of the swirl ratio, equal to about 3.
Conclusions A detailed 3D CFD investigation of the scavenging process of a uniflow, two-stroke, multi-cylinder engine, named GF56, has been carried out. GF56 is a diesel common- rail direct injection engine for the general aviation market, with six cylinders in a boxer configuration and a total volume displacement of cc. The right bank has been analyzed by considering the plenum, the intake manifold, all cylinders and the exhaust pipes. The results are analyzed in terms of trapping and charging efficiencies to show that the cylinders are characterized by similar scavenging performances, with Cylinder 5 slightly under-performing.
The scavenging process is strongly influenced by the pressure at the outlet section. Indeed, with the same exhaust pressure for all of the three cylinders, the differences are negligible and the scavenging profiles are almost on top of each other, with a somewhat lower efficiency, at high delivery ratios, for Cylinder 5, which is in the less favored position.
These results show that the position of the cylinders in the bank plays a minor role and that the same pressure profile at the exhaust is able to provide a similar scavenging performance for all the cylinders.
Moreover, a comparison between left and right banks of the engine is provided with very similar performances for both banks as a consequence of their quasi-specularity.
Finally, the influence of the intake ports geometry has been analyzed. Specifically, a modification of such a geometry of the ports is proposed to increase the swirl ratio of the in-cylinder flow field by keeping the delivery ratio nearly constant. This new geometry configuration leads to a considerable increase of the swirl ratio and provides better scavenging performance with delivery ratios generally employed during engine running conditions.
Author Contributions: Conceptualization, A. M; software, M. M; validation, M. All authors have read and agreed to the published version of the manuscript. Conflicts of Interest: The authors declare no conflict of interest. References 1. Sigurdsson, E. Numerical analysis of the scavenge flow and convective heat transfer in large two-stroke marine diesel engines. Energy , , 37— Raptotasios, S.
Application of a multi-zone combustion model to investigate the NOx reduction potential of two-stroke marine diesel engines using EGR. Energy , , — Benajes, J. Analysis of the combustion process, pollutant emissions and efficiency of an innovative 2-stroke HSDI engine designed for automotive applications. Rinaldini, C. CFD analyses on 2-stroke high speed diesel engines.
SAE Int. Engines , 4, — Heywood, J. Pulkrabek, W. Sturm, S. Wang, X. Analysis of scavenge port designs and exhaust valve profiles on the in-cylinder flow and scavenging performance in a two-stroke boosted uniflow scavenged direct injection gasoline engine. Engine Res. A high-efficiency two-stroke engine concept: The boosted uniflow scavenged direct-injection gasoline busdig engine with air hybrid operation. Engineering , 5, —, doi: Nora, M. Effects of valve timing, valve lift and exhaust backpressure on performance and gas exchanging of a two-stroke GDI engine with overhead valves.
Energy Convers. Liu, Y. Study on the synthetic scavenging model validation method of opposed- piston two-stroke diesel engine. Jia, B. Design and simulation of a two- or four-stroke free-piston engine generator for range extender applications.
Ma, F. Energies , 10, , doi: Andersen, F. CFD analysis of the scavenging process in marine two-stroke diesel engines, Vol. Wu, Y. HCCI and CAI engines for the automotive industry presents the state-of-the-art in research and development on an international basis, as a one-stop reference work.
Book Summary: This new volume covers the important issues related to environmental emissions from SI and CI engines as well as their formation and various pollution mitigation techniques. The book addresses aspects of improvements in engine modification, such as design modifications for enhanced performance, both with conventional fuels as well as with new and alternative fuels. It also explores some new combustion concepts that will help to pave the way for complying with new emission concepts.
Alternative fuels are addressed in this volume to help mitigate harmful emissions, and alternative power sources for automobiles are also discussed briefly to cover the switch over from fueled engines to electrics, including battery-powered electric vehicles and fuel cells. The authors explain the different technologies available to date to overcome the limitations of conventional prime movers fueled by both fossil fuels and alternative fuels. Book Summary: Light and Heavy Vehicle Technology, Second Edition deals with the theory and practice of vehicle maintenance, procedure, and diagnosis of vehicle trouble, including technological advances such as four-wheel drive, four-wheel steering, and anti-lock brakes.
The book reviews the reciprocating piston petrol engine, the diesel engine, the combustion chambers, and the different means of combustion processes. To counter friction, heat and wear, lubrication to the different moving parts is important. To counter excessive heat which can cause breakdown of lubricating oil films and materials such as gaskets, O-rings, the engine is designed with a cooling system that uses air, water, or engine coolants.
Petrol engines use the carburation or injection type of fuel delivery; diesel engines use a high pressure system of fuel injection owing to the higher pressures existing in the diesel combustion chamber. The text explains the operation of the other parts of the vehicle including the ignition and starter system, emission controls, layshaft gearboxes, drive lines, and suspension systems.
Heavy vehicles need highly efficient air brakes to stop them compared to the hydraulic brake systems used in smaller and lighter vehicles. The book is suitable for mechanical engineers, engine designers, students, and instructors in mechanical and automotive engineering. Author : Prof. Pune—52 Ex. Pathak Sr. Kulkarni Associate Professor Zeal E. Now the book is quite up-to-date. This edition of the book is entirely new and different from its previous editions.
We hope, the book will prove more useful and will serve its purpose better. This book will be useful for various branches, competitive examinations, engineering services and ICS Examinations. Number of problems have been solved in detail. Subject matter is supported by very good diagrams. The price of this book itself is a big consideration.
Chavan B. Department M. Faculty Member, Mech. Department, Maharashtra Institute of Tech. Lockwood Marsh, Evelyn Charles Vivian. Published by Good Press. Good Press publishes a wide range of titles that encompasses every genre. Each Good Press edition has been meticulously edited and formatted to boost readability for all e-readers and devices. Our goal is to produce eBooks that are user-friendly and accessible to everyone in a high-quality digital format. Book Summary: Diesel Engine System Design links everything diesel engineers need to know about engine performance and system design in order for them to master all the essential topics quickly and to solve practical design problems.
Based on the author's unique experience in the field, it enables engineers to come up with an appropriate specification at an early stage in the product development cycle. Links everything diesel engineers need to know about engine performance and system design featuring essential topics and techniques to solve practical design problems Focuses on engine performance and system integration including important approaches for modelling and analysis Explores fundamental concepts and generic techniques in diesel engine system design incorporating durability, reliability and optimization theories.
Book Summary: Tribological Processes in Valvetrain Systems with Lightweight Valves: New Research and Modelling provides readers with the latest methodologies to reduce friction and wear in valvetrain systems—a severe problem for designers and manufacturers.
The solution is achieved by identifying the tribological processes and phenomena in the friction nodes of lightweight valves made of titanium alloys and ceramics, both cam and camless driven.
The book provides a set of structured information on the current tribological problems in modern internal combustion engines—from an introduction to the valvetrain operation to the processes that produce wear in the components of the valvetrain. A valuable resource for teachers and students of mechanical or automotive engineering, as well as automotive manufacturers, automotive designers, and tuning engineers.
Shows the tribological problems occurring in the guide-light valve-seat insert Combines numerical and experimental solutions of wear and friction processes in valvetrain systems Discusses various types of cam and camless drives the valves used in valve trains of internal combustion engines—both SI and CI Examines the materials used, protective layers and geometric parameters of lightweight valves, as well as mating guides and seat inserts.
Book Summary: Biofuels such as ethanol, butanol, and biodiesel have more desirable physico-chemical properties than base petroleum fuels diesel and gasoline , making them more suitable for use in internal combustion engines. The book begins with a comprehensive review of biofuels and their utilization processes and culminates in an analysis of biofuel quality and impact on engine performance and emissions characteristics, while discussing relevant engine types, combustion aspects and effect on greenhouse gases.
It will facilitate scattered information on biofuels and its utilization has to be integrated as a single information source. The information provided in this book would help readers to update their basic knowledge in the area of "biofuels and its utilization in internal combustion engines and its impact Environment and Ecology".
Book Summary: The book is designed to become a valid source of information to assist the student both in and out of the classroom to attain his or her objective. Chapter 2 deals with engines and their auxiliary units. Chapters cover several aspects of design of automobile components - SI system, background mathematics and advice on problem solving, particularly exam questions.
Chapters cover essential theory part of support system for vehicles. Numerous designs and fully worked problems are provided at the end of the chapter. It is expected that as the student works through the examples and problems, he or she will develop a greater understanding of the mathematics required for engineering. To help the student develop a sound grasp of the principles covered there are many diagrams, notes and applications as an aid to develop knowledge and facilitate understanding.
Starting with the theoretical and practical thermodynamic operating cycles, the book is structured to give a description of the engines and components used to extract energy from fossil fuels and achieve high levels of productivity. The book covers areas that have the potential to affect engine efficiency and emissions including new electronic control systems, fuel injection and efficient turbocharging.
It also looks at waste heat recovery, an important development area for improving the environmental impact of ocean going vessels. It also considers new technology and individual components within the engine which means that more energy, left over from the combustion process, can be extracted and used to improve the total thermal efficiency.
The book evaluates issues of safety and environment, highlighting why the new technology must work correctly at all times and why it is necessary that engineering staff onboard understand its operation as well the consequences of any malfunction.
This key textbook takes into account the varying needs of students studying motor engineering, recognising recent changes to the Merchant Navy syllabus and current pathways to a sea-going engineering career, including National diplomas, Higher National Diploma and degree courses.
Book Summary: This book provides an introduction to basic thermodynamic engine cycle simulations, and provides a substantial set of results. Key features includes comprehensive and detailed documentation of the mathematical foundations and solutions required for thermodynamic engine cycle simulations.
The book includes a thorough presentation of results based on the second law of thermodynamics as well as results for advanced, high efficiency engines.
Case studies that illustrate the use of engine cycle simulations are also provided. Approximately delegates from 14 countries attended. The Institute was the most recent in a series beginning with "Instrumentation for Combustion and Flow in Engines", held in Vimeiro, Portugal and followed by "Combusting Flow Diagnostics" conducted in Montechoro, Portugal in Together, these three Institutes have covered a wide range of experimental and theoretical topics arising in the research and development of combustion systems with particular emphasis on gas-turbine combustors and internal combustion engines.
The emphasis has evolved roughly from instrumentation and experimental techniques to the mixture of experiment, theory and computational work covered in the present volume.
As the title of this book implies, the chief aim of this Institute was to provide a broad sampling of problems arising with time-dependent behaviour in combustors. In fact, of course, that intention encompasses practically all possibilities, for "steady" combustion hardly exists if one looks sufficiently closely at the processes in a combustion chamber. The point really is that, apart from the excellent paper by Bahr Chapter 10 discussing the technology of combustors for aircraft gas turbines, little attention is directed to matters of steady performance.
The volume is divided into three parts devoted to the subjects of combustion-induced oscillations; combustion in internal combustion engines; and experimental techniques and modelling. Book Summary: The science and technology of materials in automotive engines provides an introductory text on the nature of the materials used in automotive engines. It focuses on reciprocating engines, both four and two stroke, with particular emphasis on their characteristics and the types of materials used in their construction.
The book considers the engine in terms of each specific part: the cylinder, piston, camshaft, valves, crankshaft, connecting rod and catalytic converter. The materials used in automotive engines are required to fulfil a multitude of functions. It is a subtle balance between material properties, essential design and high performance characteristics.
The science and technology of materials in automotive engines describes the metallurgy, chemical composition, manufacturing, heat treatment and surface modification of these materials. It also includes supplementary notes that support the core text. The book is essential reading for engineers and designers of engines, as well as lecturers and graduate students in the fields of automotive engineering, machine design and materials science looking for a concise, expert analysis of automotive materials.
Provides a detailed introduction to the nature of materials used in automotive engines Essential reading for engineers, designers, lecturers and students in automotive engineering Written by a renowned expert in the field. Book Summary: This book covers the various advanced reciprocating combustion engine technologies that utilize natural gas and alternative fuels for transportation and power generation applications. It is divided into three major sections consisting of both fundamental and applied technologies to identify but not limited to clean, high-efficiency opportunities with natural gas fueling that have been developed through experimental protocols, numerical and high-performance computational simulations, and zero-dimensional, multizone combustion simulations.
Particular emphasis is placed on statutes to monitor fine particulate emissions from tailpipe of engines operating on natural gas and alternative fuels. Book Summary: This vintage book is an illustrated manual for motor boat, launch and yacht owners; operators of marine gasoline engines, and amateur boat-builders. It is a comprehensive guide to the design, construction, installation and operation of maritime motors, and contains instructions for the design and construction of motor boats.
Many vintage books such as this are becoming increasingly scarce and expensive. We are republishing this volume now in an affordable, high-quality edition complete with a specially commissioned new introduction on building boats. Book Summary: Piston Engine-Based Power Plants presents Breeze's most up-to-date discussion and clear and concise analysis of this resource, aimed at those working and researching in the area.
Various engine types including Diesel and Stirling are discussed, with consideration of economic factors and important planning considerations, such as the size and speed of the plant.
Breeze also evaluates the emissions which piston engines can create and considers ways of planning for and controlling those. Explores various types of engines used to power automotive power plants such as internal combustion, spark-ignition and dual-fuel Discusses the engine cycles, size and speed Evaluates emissions and considers the various economic factors involved.
Book Summary: Kinematic and dynamic analysis are crucial to the design of mechanism and machines. In this student-friendly text, Martin presents the fundamental principles of these important disciplines in as simple a manner as possible, favoring basic theory over special constructions.
Among the areas covered are the equivalent four-bar linkage; rotating vector treatment for analyzing multi-cylinder engines; and critical speeds, including torsional vibration of shafts. The book also describes methods used to manufacture disk cams, and it discusses mathematical methods for calculating the cam profile, the pressure angle, and the locations of the cam. This book is an excellent choice for courses in kinematics of machines, dynamics of machines, and machine design and vibrations.
This book compiles technical papers of five representatives from the national non-governmental air pollution prevention association of Argentina, France, West Germany, Japan, and the United Kingdom that aims to determine how they might work together cooperatively to contribute to the conservation of the world's air resources The topics discussed include the Swedish experiences on sensory evaluation of odorous air pollutant intensities; chronic fluoride intoxication due to air pollution; and organic ozone reactions as singlet oxygen sources.
The emission and control of air pollutants from the incineration of municipal solid wastes and gaseous plume diffusion about isolated structures of simple geometry are also covered.
This publication is a good reference for environmentalists and students interested in the scientific, technological, and administrative aspects of air pollution control. Skip to content. READ MORE Book Summary: This book addresses the two-stroke cycle internal combustion engine, used in compact, lightweight form in everything from motorcycles to chainsaws to outboard motors, and in large sizes for marine propulsion and power generation.
READ MORE Book Summary: A Textbook of Automobile Engineering is a comprehensive treatise which provides clear explanation of vehicle components and basic working principles of systems with simple, unique and easy-to-understand illustrations.
READ MORE Book Summary: Engineering Thermodynamics is a comprehensive text which presents the broad spectrum of the principles of thermodynamics while encapsulating the theoretical and practical aspects of the field. Basic Mechanical Engineering Author : N. Engineering Thermodynamics Author : Gupta S. Publisher : S. Field,John M.
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