xviii
PREFACE
From a fundamental point of view, how the fuel-air mixture within an inter-
nal combustion engine cylinder is ignited appropriately organizes the field. From
the method of ignition-spark-ignition or compression-ignition-follows each
type of engine's important features: fuel requirements, method of mixture
prep
aration, combustion chamber design, details of the combustion process, method
of load control, emission formation mechanisms, and performance and efficiency
characteristics. While many engine processes (such as intake and exhaust flows,
convective heat transfer, and friction) are similar in both types of engines, this
distinction is fundamental and lies behind the overall organization of the book.
The book is arranged in four major sections. The first (Chapters 1 to 5)
provides an introduction to, and overview of, the major characteristics of
spark-
ignition and compression-ignition engines, defines the parameters used to
describe engine operation, and develops the necessary thermodynamics and com-
bustion theory required for a quantitative analysis of engine behavior. It con-
cludes with an integrated treatment of the various methods of analyzing idealized
models of internal combustion engine cycles. The second section (Chapters
6
to
8)
focuses on engine flow phenomena. The details of the gas exchange process-
intake and exhaust processes in four-stroke and scavenging in two-stroke
cycles-and the various methods of supercharging engines-are reviewed. Fuel
metering methods for spark-ignition engines and air- and fuel-flow phenomena in
intake manifolds are described. The essential features of the various types of fluid
motion within the engine cylinder are then developed. These flow processes
control the amount of air an engine will induct (and therefore its power), and
largely govern the rate at which the fuel-air mixture will burn during combustion.
The third section of the book focuses on engine combustion phenomena.
These chapters (9, 10, and 11) are especially important. The combustion process
releases the fuel's energy within the engine cylinder for eventual conversion to
useful work. What fraction of the fuel's energy is converted depends strongly on
how combustion takes place. The spark-ignition and compression-ignition engine
combustion processes (Chapters 9 and 10, respectively) therefore influence essen-
tially all aspects of engine behavior. Air pollutants are undesirable byproducts of
combustion. Our extensive knowledge of how the major pollutants form during
these combustion processes and how such emissions can be controlled is
reviewed in Chapter 11.
The last section of the book focuses on engine operating characteristics. First,
the fundamentals of engine heat transfer and friction, both of which detract from
engine performance, are developed in Chapters 12 and 13. Chapter 14 then
focuses on the methods available for predicting important aspects of engine
behavior based on realistic models of engine flow and combustion processes.
Since the various thermodynamic-based and fluid-mechanic-based models which
have been developed over the past
fifteen years or so are increasingly used in
engine research and development, a knowledge of their basic structure and capa-
bilities is most important. Then, Chapter 15 presents a summary of how the
operating characteristics-power, efficiency, and emissions--of spark-ignition
and compression-ignition engines depend on the major engine design and
oper-
PREFACE
X~X
sting
variables. These final two chapters effectively integrate the analytical under-
standing and practical knowledge of individual engine processes together to
describe overall spark-ignition and compression-ignition engine behavior.
Material on internal combustion engine fuels is distributed appropriately
the book. Each chapter is extensively illustrated and referenced, and
includes problems for both undergraduate and graduate level courses.
While this book contains much advanced material on engine design and
operation intended for the practitioner, each major topic is developed from its
beginnings and the more sophisticated chapters have introductory sections to
facilitate
their use in undergraduate courses. The chapters are extensively cross-
and indexed. Thus several arrangements of the material for a course
on engines can be followed. For example, an introductory course on internal
combustion engines could begin with Chapters 1 and
1,
which review the differ-
ent types of engines and how their performance is characterized, and continue
with the parts of Chapters
3
and 5, which introduce the key combustion concepts
necessary to understand the effects of fuellair ratio, and ideal cycle analysis. Se-
lections from the introductory sections of Chapters
6,9, 10, ll, and 15 could then
be used to explain several of the practical and design aspects of spark-ignition
and diesel engine intake and exhaust processes, combustion, emissions, and per-
formance. A more advanced course would review this introductory material more
rapidly, and then move on to those sections of Chapters
4
and 5, which cover
fuel-air cycle analysis, a more extensive discussion of engine breathing using addi-
tional sections of Chapter 6, and more in-depth treatment of engine combustion
and emissions processes based on the appropriate sections of Chapters 9,
10,
and
11. Material on engine heat transfer and friction selected from Chapters 12 and
13
could be included next. While Chapter 14 on modeling the thermodynamics
and fluid dynamics of real engine processes is primarily intended for the pro-
fessional scientist and engineer, material from this chapter along with selections
from Chapter 15 could
be
used to illustrate the performance, efficiency, and emis-
sions characteristics of the different types of internal combustion engines. I have
also used much of the more sophisticated material in Chapters 6 through 15 for
review seminars on individual engine topics and more extensive courses for pro-
fessional engineers, an additional important educational and reference
opportunity.
Many individuals and organizations have assisted me in various ways as I
have worked on this book over the past ten or so years. I am especially indebted
to my colleagues in the Sloan Automotive Laboratory at
M.I.T., Professors
Wai
K.
Cheng, Ahmed
F.
Ghoniem, and James C. Keck, and Drs. Jack A. Ekchian,
David P. Hoult, Joe M. Rife, and Victor W. Wong, for providing a stimulating
environment in which to carry out engine research and for assuming additional
burdens as a result of my writing. Many of the Sloan Automotive Laboratory's
,
students have made significant contributions to this text through their research;
their names appear in the reference lists. The U.S. Department of Energy provid-
ed support during the early stages of the text development and funded the work
on engine cycle simulation used extensively in Chapters 14 and 15. I am grateful