Customer Reviews

Design and Simulation of Four Stroke Engines [R-186]

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As a relatively new designer of the four-stroke-cycle engine, Design and Simulation of Four-Stroke Engines is by far the most important single source of information to me. I also own Blair's Design and Simulation of Two-Stroke Engines. This book covers four-stroke engines with the same blend of sophisticated full thermodynamic cycle modeling and empirical insight. An introductory chapter enlightens the reader to the geometry of the four-stroke engine, defines terminology as it will be found in subsequent chapters and reviews thermodynamic theory as it will be applied to the computer model. Chapter 2, as in Design and Simulation of Two-Stroke Engines, lays the ground work for the heart of the computer model, the prediction of unsteady gas flow through engine ducting. A more complete explanation of a one dimensional method for the prediction of unsteady, compressible flow through engine ducting simply cannot be found. The following chapter is dedicated to the definition and measurement of an "actual" coefficient of discharge for poppet valve systems and why they are critically important to the model as compared with the more traditional ideal or isentropic coefficients of discharge. Chapter 4 explains the theory for the 2-zone burn model for combustion in the cylinder while providing insight into the proper design and geometry of the combustion chamber. Throughout the book, the focus is on the naturally-aspirated four-stroke engine, however, where applicable information is given on turbocharging and direct and in-direct diesel combustion. One of the most important chapters to the actual user of the computer model is Chapter 5. I have used Prof. Blair's software in two-stroke and four-stroke versions for the Mac and now use Optimum Power's offerings for the IBM compatible. No less than 6 different engines are analyzed using the simulation ranging from a string trimmer to a motorcycle to a turbo-diesel automobile. All the relevant data is given to create the geometry in the model. As each engine is discussed, the strengths of the particular design are pointed out and explained via the pressure wave diagrams created by the model itself. All these engines display very good correlation with actual measurements even though they vary in output from 1 kW to 525 kW. In addition to the geometric data for these engines, the combustion input parameters for the model are also given which are from actual running engines. Therefore, one could take this combustion information and apply it to a similar model with good confidence that this is close to reality. In order to reduce the design cycle time, Blair has included an entire chapter on empirical approaches to design geometry that are intended to be good starting points for input into the model. I find the intake tract tuned length program and the poppet valve time-area program the most useful. A final chapter is devoted to the current state of the design methodology for intake and exhaust silencing systems and how the thermodynamics from Chapter 2 are now being implemented to predict silencer performance. In conclusion, Design and Simulation of Four-Stroke Engines is a highly recommended read for anyone involved in the design or tuning of four-stroke engines and a must for anyone involved in the thermodynamic modeling of these engines.

This extensive new work by Professor Blair on four-stroke engine design is a welcome addition to his previously published treatises on two-stroke engines. Coverage of material spans basic ideas of unsteady gas flow, to the detailed analysis of single and muticylinder engine configurations using a state-of-the-art computer code. One of the highlights of the book from my own perspective is the author's coverage of engines with historical significance. The new insight gained from detailed analysis of their operating behavior using the computer code gives one a much greater appreciation of the intricacies of efficient engine design. This book will be a valuable asset to teacher and and student alike, by providing a broad range of relevant subject matter in a single volume. I highly recommend this excellent book.

As was the case with the Author's previous books on the design of Two-Stroke Engines, this book follows the same pattern of building a design simulation package based on sound basic theories relating to the IC engine which have been developed over a long period and backing up the theory with many real world examples. Chapter 1 begins with a very easy to follow description of the four stroke engine with the diagrams and accompaning text easily understood. I particularly like how the geometry of the aperture posed by a poppet valve is handled and also the method of providing the valve lift characteristics as a function of crankangle. The method allows the valve lift data to be easily changed when using the simulation program for the purpose of optimising the valve open period and lift.Care must be taken when transferring the valve lift data from the simulation to the actual cam requirements, since one must allow for tappet clearance and cam manufacturers prefer to give opening and closing data at 0.050 in. lift. In the latter portion of the chapter the author provides some relavant comparisons of the thermodynamic cycles of IC engines with some good practical worked examples to illustrate his point.While the use of the ideal Otto cycle or Diesel cycle would produce inaccurate simulations, the chapter concludes by showing how the introduction of the real combustion process, heat transfer loss, and friction and pumping losses into the simulation process yields predictions that give good correlation with measured data. In chapter 2 the concept of pressure waves and unsteady gas flow is introduced. The Schlieren pictures provide a wonderful illustration of a pulse from a pressure wave travelling along a pipe and enters the atmosphere. At this juncture the reader must get a good grasp of unsteady gas flow and pressure wave motion, otherwise, the succeeding chapters of this book will be mostly meaningless. After the initial introduction to wave motion the chapter goes on to provide the theory and illustrations of pressure waves as they transverse through numerous duct shapes, branch systems and duct endings. The concept of the duct being broken into mesh lengths is introduced and accuracy is improved by the addition of heat transfer through the ducts during the process. In chapter 3 the author evaluates three distinct methods regarding the measurement and use of coefficients of disharge for the valves and ducts.Data is provided to justify the use of the "Actual Discharge Coefficients" method in the simulation. The remainder of the chapter provides examples of the CD's used for all the engine duct possibilities. A clear explanation is provided in chapter 4 of the practical aspects of combustion in actual engines. The choice of a combustion model encompasing a heat release rate and mass fraction burned described by Vibe coefficients appears justified from the correlation with the practical data provided in this chapter. Combustion models for both spark ignition and Diesel engines are presented. The wide versatility of the Blair simulation is demonstrated in chapter 5 were measured and calculated power comparisons are made for a string trimmer engine at less than 1KW of power to the Infinity IRL racing engine making over 500 KW of power. Correlation of engine parameters is quite good for both these applications as is a varied number of other applications in between. The simulation package appears to be a must for the modern engine designer. Some excellent emperical engine design data is provided in chapter 6 while chapter 7 provides noise reduction methods for both intake and exhaust. A superb book for just about anyone with an interest in the design of internal combustion engines.I have designated this book as the new text book for an IC engine course I will be teaching to mechanical enginneering students in the spring semester at the University of South Florida in Tampa.

The most complete and straightforward four-stroke text to date. This book is a must have for any serious engine designers library. Filled with many gems of wisdom, insight, and direct calculations relating to four-stroke engine design as well as historical background in engine design.. The book is so packed with information that numerous readings may be necessary to grasp all that Blair has to offer. Design examples abound from the top engine designers in the world (although anonymity is required). The professor has done an exemplary job in assimilating the results to find the common thread among the great current and past engine designers. A good review of thermodynamics for the past and present college students and a good stating place to those without college thermodynamics. The heart of the book is wave dynamics in the engine design process, both in theory and application. Finally for those that must silence the music of the 4-stroke there is a section on muffler design.

The text is well written, and well organized. The first few chapters provide a good overview of combustion engines including modeling techniques. More advanced topics are treated in later chapters.

Many engines are compared, and the author often suggests heuristics or rules of thumb which tend to work as well as more advanced methods. The balanced look at heuristic approaches, and complex model based approaches are carefully evaluated, and the interested reader is given enough information to make decisions on given design choices. I recommend this to all interested in engine design or modeling.