The internal-combustion engine in theory and practice : Volume I : Thermodynamics, Fluid Flow, Performance

The Internal-Combustion Engine

in Theory and Practice

Volume I : Thermodynamics, Fluid Flow, Performance

Second Edition, Revised

by Charles Fayette Taylor

Professor of Automotive Engineering, Emeritus

Massachusetts Institute of Technology

THE M.I.T. PRESS

Massachusetts Institute of Technology

Cambridge, Massachusetts, and London, England

Copyright 0 1960 and 1966 and new material 0 1985 by The Massachusetts Institute

of Technology

All rights reserved. No part of this book may be reproduced in any form by any

electronic or mechanical means (including photocopying, recording, or information

storage and retrieval) without permission in writing from the publisher.

Printed and bound in the United States of America.

First MIT Press paperback edition, 1977

Second edition. revised. 1985

Library of Congress Cataloging in Publication Data

Taylor, Charles Fayette, 1894-

The internal-combustion engine in theory and practice.

Bibliography: v. 1, p.

Includes index.

Contents: v. 1. Thermodynamics, fluid flow,

1. Internal-combustion engines. I. Title.

performance.

TJ785.T382 1985 621.43 84-28885

ISBN 978-0-262-20051-6 (hc. : alk. paper+978-0-262-70026-9 (pb. : alk. paper)

20 19 18 17 16 15 14

Preface

When the author undertook the task of teaching in the field of internal￾combustion engines at the Massachusetts Institute of Technology, it was

evident that commercial development had been largely empirical and

that a rational quantitative basis for design, and for the analysis of per￾formance, was almost entirely lacking. In an attempt to fill this gap, the

Sloan Laboratories for Aircraft and Automotive Engines were established

in 1929 at t.he Massachusetts Institute of Technology, largely through

the generosity of Mr. Alfred P. Sloan, Jr., and the untiring enthusiasm of

the late Samuel S. Stratton, then President of RUT.

The intervening years have been spent in research into the behavior

of internal-combustion engines and how to control it. A large amount

of the laboratory work has been done by students as part of their re￾quirements for graduation. Other parts have been done by the teaching

staff and the professional laboratory staff with funds provided by gov￾ernment or by industry.

The results of this work, translated, it is hoped, into convenient form

for practical use in engine design and research, is the subject of these

two volumes.

Grateful acknowledgment is made to all those who in various capacities

-students, teaching staff , technical staff , and staff engineers-have

contributed by their laboratory work, their writings, and their criticism.

V

vi PREFACE

Special acknowledgment and thanks are due to Professor E. S. Taylor,

Director of the Gas Turbine Laboratory at MIT and long a colleague

in the work of the Sloan Automotive Laboratories, and to Professors

A. R. Rogowski and T. Y. Toong of the Sloan Laboratories teaching staff.

The author will be grateful to readers who notify him of errors that

diligent proofreading may have left undiscovered.

C. FAYETTE TAYLOR

Cambridge, Massachusetts

November 1976

Preface to Second Edition, Revised

Since the publication of this volume in 1966 there have been no devel￾opments that require changes in the basic principles and relationships

discussed in this volume. Neither have there been any important com￾petitors to the conventional reciprocating internal-combustion engine for

land and sea transportation and for most other purposes except aircraft,

nuclear-powered vessels, and large electric generating stations. The total

installed power of reciprocating internal-combustion engines still exceeds

that of all other power sources combined by at least one order of magni￾tude (see p. 5).

On the other hand, there have been two important changes in empha￾sis, one toward improved fuel economy and the other toward reduced air

pollution by engine exhaust gases.

The petroleum crisis of the 1970s caused the increased emphasis on fuel

economy, especially in the case of road vehicles and large marine Diesel

engines. In the case of passenger cars, the greatest gains have been made

by reducing the size, weight, and air resistance of the vehicles themselves

and by reducing engine size accordingly. This change, plus wider-range

transmissions and reduced ratio of maximum engine power to car weight

allow road operation to take place nearer to the engine’s area of best fuel

economy.

Increases in fuel economy of spark-ignition engines have been accom￾plished chiefly through improved systems of control of fuel-air ratio, fuel

distribution, and spark timing. In the case of Diesel engines, supercharg￾ing to higher mean effective pressures, and in many cases reduction in

rated piston speed, have achieved notable improvements in efficiency.

In the other major change in emphasis since the 1960s, public demand

PREFACE vii

for reduced air pollution has brought stringent government limitations on

the amount of undesirable emissions from road-vehicle engines and other

power plants. In the United States, the problem of reducing air pollution

has resulted in more research, development, and technical literature than

any other event in the history of the internal-combustion engine. The

methods used for reducing pollution are outlined in Volume 2, together

with references to the existing literature. See also the references on pages

555 and 556 of this volume.

The developments described above have been greatly assisted by the

recent availability of powerful computers. These are now generally used

in engine research, design, and testing. They make possible mathematical

“modeling” of many aspects of engine behavior, including fluid flow,

eombustion, and stress distribution. Engine test equipment and proce￾dures are now usually “computerized.” An extremely important applica￾tion of computers, now expanding rapidly, is the use of relatively small

electronic computer systems applied to individual engine installations for

purposes of control and the location of malfunctions. The use of such

systems in road vehicles is becoming general in the United States, and it

has assisted greatly in the control of exhaust emissions, as explained in

Volume 2.

The developments mentioned here are covered in more detail at appro￾priate points in these two volumes.

C. FAYETTE TAYLOR

January 1984

Contents

Volume I

Thermodynamics, Fluid Flow, Performance

Chapter 1 INTRODUCTION, SYMBOLS, UNITS, DEFINITIONS

2 AIR CYCLES

3 THERMODYNAMICS OF ACTUAL WORKING FLUIDS

4 FUEL-AIR CYCLES

5 THE ACTUAL CYCLE

6 AIR CAPACITY OF FOUR-STROKE ENGINES

7 TWO-STROKE ENGINES

8 HEAT LOSSES

1

22

40

67

107

147

211

266

9 FRICTION, LUBRICATION, AND WEAR 312

ix

X CONTENTS

10 COMPRESSORS, EXHAUST TURBINES,

HEAT EXCHANGERS 362

11 INFLUENCE OF CYLINDER SIZE

ON ENGINE PERFORMANCE 401

12 THE PERFORMANCE OF UNSUPERCHARGED ENGINES 418

13 SUPERCHARGED ENGINES AND THEIR PERFORMANCE 456

Appendix 1

2

3

4

5

6

7

8

SYMBOLS AND THEIR DIMENSIONS

PROPERTIES OF A PERFECT GAS

FLOW OF FLUIDS

ANALYSIS OF LIGHT-SPRING INDICATOR DIAGRAMS

HEAT TRANSFER BY FORCED CONVECTION

BETWEEN A TUBE AND A FLUID

FLOW THROUGH Two ORIFICES IN SERIES

STRESSES DUE TO MOTION AND GRAVITY

IN SIMILAR ENGINES

BASIC ENGINE-PERFORMANCE EQUATIONS

495

500

503

510

514

516

518

520

Bibliography 523

Charts

C-1, C-2, C-3, C-4 are folded in pocket attached to rear cover.

Index 557

Introduction,

Symbols,

one Units,

Definitions

Heat engines can be classified as the external-combustion type in which

the working fluid is entirely separated from the fuel-air mixture, heat

from the products of combustion being transferred through the walls of

a containing vessel or boiler, and the internal-combustion type in which

the working fluid consists of the products of combustion of the fuel-air

mixture itself.

Table 1-1 shows a classification of the important types of heat engine.

At the present time the reciprocating internal-combustion engine and

the steam turbine are by far the most widely used types, with the gas

turbine in wide use only for propulsion of high-speed aircraft.

A fundamental advantage of the reciprocating internal-combustion

engine over power plants of other types is the absence of heat exchangers

in the working fluid stream, such as the boiler and condenser of a steam

plant.* The absence of these parts not only leads to mechanical simpli￾fication but also eliminates the loss inherent in the process of transfer of

heat through an exchanger of finite area.

The reciprocating internal-combustion engine possesses another im￾portant fundamental advantage over the steam plant or the gas turbine,

namely, that all of its parts can work at temperatures well below the

maximum cyclic temperature. This feature allows very high maximum

* Gas turbines are also used without heat exchangers but require them for max￾imum efficiency.

1

2 INTRODUCTION, SYMBOLS, UNITS, DEFINITIONS

Table 1-1

Classification of Heat Engines

Reciprocating Size of Status

Class Common Name or Rotary Units * Principal Use (1960)

External corn- steam engine

bustion steam turbine

hot-air engine

closed-cycle

gas turbine

Internal com- gasoline ennine

bustion

Diesel engine

gas engine

gas turbine

jet engine

reciprocating

rotary

reciprocating

rotary

reciprocating

reciprocating

reciprocating

rotary

rotary

S-M

M-L

S

M-1,

6-M

6-M

S-M

M-L

M-L

locomotives

electric power,

large marine

none

electric power,

marine

road vehicles,

small marine,

small industrial.

aircraft

road vehicles, in￾dustrial, loco￾motives, marine,

electric power

industrial, electric

power

electric power, air￾craft

aircraft

obsolescent

active

obsolete

experimental

active

active

active

active

active

*Size refers to customary usage. There are exceptions. L = hre, over 10,OOO hp, M = medium,

1000-10,000 hp, S = small, under 1000 hp.

cyclic temperatures to be used and makes high cyclic efficiencies possible.

Under present design limitations these fundamental differences give

the following advantages to the reciprocating internal-combustion en￾gine, as compared with the steam-turbine power plant, when the pos￾sibilities of the two types in question have been equally well realized:

1. Higher maximum efficiency.

2. Cower ratio of power-plant weight and bulk to maximum output

3. Greater mechanical simplicity.

4. The cooling system of an internal-combustion engine handles a

much smaller quantity of heat than the condenser of a steam power

plant of equal output and is normally operated at higher surface temper￾atures. The resulting smaller size of the heat exchanger is a great ad￾vantage in vehicles of transportation and in other applications in which

cooling must be accomplished by atmospheric air.

These advantages are particularly conspicuous in relatively small

units.

(except, possibly, in the case of units of more than about 10,000 hp).

INTRODUCTION, SYMBOLS, UNITS, DEFINITIONS 3

On the other hand, practical advantages of the steam-turbine power

1. The steam power plant can use a wider variety of fuels, including

2. More complete freedom from vibration.

3. The steam turbine is practical in units of very large power (up to

200,000 hp or more) on a single shaft.

The advantages of the reciprocating internal-combustion engine are of

especial importance in the field of land transportation, where small weight

and bulk of the engine and fuel are always essential factors. In our

present civilization the number of units and the total rated power of

internal-combustion engines in use is far greater than that of all other

prime movers combined. (See Tables 1-2 and 1-3.) Considering the

great changes in mode of life which the motor vehicle has brought about

in all industrialized countries, it may safely be said that the importance

of the reciprocating internal-combustion engine in world economy is

second to that of no other development of the machine age.

Although the internal-combustion turbine is not yet fully established

as a competitor in the field of power generation, except for aircraft, the

relative mechanical simplicity of this machine makes it very attractive.

The absence of reciprocating parts gives freedom from vibration com￾parable to that of the steam turbine. This type of power plant can be

made to reject a smaller proportion of the heat of combustion to its

cooling system than even the reciprocating internal-combusfion engine

-a feature that is particularly attractive in land and air transporta￾tion.

Cooling the blades of a turbine introduces considerable mechanical

difficulty and some loss in efficiency. For these reasons most present

and projected designs utilize only very limited cooling of the turbine

blades, with the result that the turbine inlet temperature is strictly

limited. Limitation of turbine inlet temperature imposes serious limita￾tions on eficiency and on the output which may be obtained from a

given size unit. Except in aviation, where it is already widely used, it is

not yet clear where the internal-combustion turbine may fit into the

field of power development. Its future success as a prime mover will

depend upon cost, size, weight, efficiency, reliability, life, and fuel cost

of actual machines as compared with competing types. Although this

type of machine must be regarded as a potential competitor of the re￾ciprocating internal-combustion engine and of the steam power plant, it

is unlikely that it will ever completely displace either one.

plant over the reciprocating internal-combustion engine are

solid fuels.

4 INTRODUCTION, SYMBOLS, UNITS, DEFINITIONS

Table 1-2

Estimated Installed Rated Power, United States, 1983

Road vehicles

Off-road vehicles

Diesel-electric power

Small engines, lawnmowers, etc.

Small water craft

Small aircraft

R.R. locomotives

Total I.C.E.

(9) Steam, hydroelectric, nuclear

(10) Jet aircraft (nonmilitary)

Total non I.C.E.

Ratio I.C.E. to other sources

(U.S. military and naval forces are not included)

Millions of hp.

20,000

250

60

50

250

36

7

20,693

700

25

725

28.7

Method of Estimate

Item No. Units and Estimated Unit Power Source

(1) 160 million vehicles at 125 hp

(2) 2.3 million farms at 100 hp, plus other

off-road 10%

(3) 8% of item 9

(4) 25 million units at 2 hp

(5) 5 million at 50 hp

(6) 200,000 airplanes at 200 hp

(7) 30,000 locomotives at 1200 hp

(8) 853 vessels at 8000 hp

(9) from 1984 data

(10) 2500 aircraft at 10,000 hp

WA

WA

est.

est.

est.

SA

WA

WA

WA

SA

WA: World Almanac, 1984. SA: Statistical Abstracts, U.S. Dept. of

Commerce, 1983. Average unit power is estimated.

Power plants which combine the reciprocating internal-combustion

engine with a turbine operating on the exhaust gases offer attractive

possibilities in applications in which high output per unit size and weight

are of extreme importance. The combination of a reciprocating engine

with an exhaust-gas turbine driving a supercharger is in wide use. (See

Chapter 13.)

FUNDAMENTAL UNITS 5

Table 1-3

Power Production in the United States, 1982

(1) Electric power

Installed capacity (including Diesel)

1982 output

Use factor 0.45

760 X lo6 hp

3 X 1OI2 hp-hr

(2) Automobiles

No. passenger cars

1982 output

Use factor

144 X lo6

864 X lo9 hp-hr

0.007

Method of Estimate

= 0.45. 3 x 1012

760 X lo6 X 365 X 24 Use factor =

(2) 160 million vehicles less 10% for trucks = 144 million. From World

Almanac, average automobile goes 9000 miles per year. Estimate 30 mph

=300 hrs at 20 hp=6000 hp-hr per car. At average rating of 100 hp

per car, 6ooo =0.007. 100 X 365 X 12 Use factor =

Road vehicles used about half of U.S. petroleum consumption, or about

100 billion gallons, in 1982 (WA).

SYMBOLS

The algebraic symbols, subscripts, etc. used in this book are listed in

Appendix 1. As far as possible, these conform with common U.S. prac￾tice. Definitions of symbols are also given in the text to the point at

which they should be entirely familiar to the reader.

FUNDAMENTAL UNITS

The choice of the so-called fundamental units is largely a matter of con￾venience. In most fields of pure science these are three in number,

namely, length (L), time (t) and either force (F) or mass (M). Through

Newton’s law, Joule’s law, et,c., all other quantities can be defined in

terms of three units.

Since this book must, of necessity, use the results from many fields of

scientific endeavor in which different systems of fundamental units oc-

6 INTRODUCTION, SYMBOLS, UNITS, DEFINITIONS

cur,* it has been found convenient, if not almost necessary, to employ

a larger number of fundamental dimensions, namely length (L), time (t),

force (F), mass (M), temperature (O), and quantity of heat (Q). How

these are used and related appears in the next section.

Units of Measure

Throughout this book an attempt has been made to keep all equations

in such form that any set of consistent units of measure may be em￾ployed. For this purpose Newton’s law is written

F = Ma/go (1-1)

where F is force, M is mass, a is accelerations, and go is a proportionality

constant whose value depends upon the system of units used. The

dimensions of go are determined from Newton’s law to be

mass X acceleration mass X length

fbrce force x time2 - = MLt-2F-1

Under these conditions go must appear in any equation relating force

and mass in order that the equation shall be dimensionally homogeneous.

(The word mass has been used whenever a quantity of material is speci￾fied, regardless of the units used to measure the quantity.) If the

technical system of units is employed, that is, the system in which force

and mass are measured in the same units, go becomes equal in magnitude

to the standard acceleration of gravity. Thus in the foot, pound-mass,

pound-force, second system generally used by engineers go = 32.17 lbm t

ft per lbf t sec2. In the foot, slug, pound-force, second system, or in the

usual cgs system, go is numerically equal to unity. go must not be con￾fused with the acceleration of gravity, g, which depends on location and

is measured in units of length over time squared. In the technical

system g has a value close to 32.17 ft per sec2 at any point on the earth’s

surface.

In problems involving heat and work the dimensional constant J is

defined as

w@JQ (1-2)

* For example, in American thermodynamic tables the unit of mass is the pound,

t From this point on pound mass is written lbm and pound force, lbf.

whereaa in many tables of density, Viscosity, etc, the unit of maas is the slug.

GENERAL DEFINITIONS 7

in which the circle indicates a cyclic process, that is, a process which re￾turns the system to its original state.

20 is work done by a system minus the work done on the system, and

Q is the heat added to the system, minus the heat released by the

The dimensions of J are

system.

units of work

units of heat

force X length

units of heat - = FLQ-I

and J must appear in any equation relating heat and work in order to

preserve dimensional homogeneity. * In foot, pound-force, Btu units J

is 778.ft lbf per Btu.

Another dimensional constant, R, results from the law of perfect

gases :

pV = (M/m)RT

p = pressure

V = volume

M = mass of gas

m = molecular weight of gas

T = absolute temperature

Molecular weight may be considered dimensionless, since it has the

R thus has the dimensions

same value in any system of units.t

force X length

temperature X mass - = FLB-~M-' pressure X volume

temperature X mass -

In the foot, pound-force, pound-mass,, degree Rankine (OF + 460)

system R = 1545 ft lbf/"R for m lbm of material.

GENERAL DEFINITIONS

In dealing with any technical subject accurate definition of technical

terms is essential. Whenever technical terms are used about whose

* For a more complete discussion of this question see refs 1.3 and 1.4.

t The official definition of molecular weight is 32 times the ratio of the mass of H

molecule of the gas in question to the mass of a molecule of 02.

8 INTRODUCTION, SYMBOLS, UNITS, DEFINITIONS

definitions there may be some doubt, your author has endeavored to state

the definition to be used. At this point, therefore, it will be well to define

certain basic terms which appear frequently in the subsequent discussion.

Basic Types of Reciprocating Engine *

Spark-Ignition Engine. An engine in which ignition is ordinarily

caused by an electric spark.

Compression-Ignition Engine. An engine in which ignition

ordinarily takes place without the assistance of an electric spark or of a

surface heated by an external source of energy.

Diesel Engine. The usual commercial form of the compression￾ignition engine.

Carbureted Engine. An engine in which the fuel is introduced to

the air before the inlet valve has closed.?

Carburetor Engine. A carbureted engine in which the fuel is

introduced to the air by means of a carburetor. (Most spark-ignition

engines are also carburetor engines.)

Injection Engine. An engine in which the fuel is injected into the

cylinder after the inlet valve has closed. (All Diesel engines and a few

spark-ignition engines are this type.)

Gas Turbines

In this book the words gas turbine are taken to mean the internal￾combustion type of turbine, that is, one in which the products of com￾bustion pass through the turbine nozzles and blades. External-com￾bustion (closed cycle) gas turbines are not included.

DEFINITIONS RELATING TO ENGINE

PERFORMANCE

Efficiency

In the study of thermodynamics the efficiency of a cyclic process

(that is, a process which operates on a given aggregation of materials in

* It is assumed that the reader is familiar with the usual nomenclature of engine

parts and the usual mechanical arrangements of reciprocating internal-combustion

engines. If this is not the case, a brief study of one of the many descriptive books on

the subject should be undertaken before proceeding further.

t Engines with fuel injected in the inlet ports are thus carbureted engines.