Handbook ofMECHANICAL ENGINEERINGMECHANICAL ENGINEERINGMECHANICAL ENGINEERINGMECHANICAL ENGINEERINGMECHANICAL ENGINEERING

Handbook of

MECHANICALMECHANICALMECHANICALMECHANICALMECHANICALENGINEERINGENGINEERINGENGINEERINGENGINEERINGENGINEERING

ByDR. J. SRINIVAS

Ph.D., Mechanical EngineeringChaitanya Engineering College, Visakhapatnam

Andhra Pradesh

UNIVERSITY SCIENCE PRESS(An Imprint of Laxmi Publications Pvt. Ltd.)

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HANDBOOK OF MECHANICAL ENGINEERING

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First Edition : 2004, Reprint : 2007, 2009, Second Edition : 2011ISBN 978-81-908565-0-8

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CONTENTS

Chapter-1 THERMODYNAMICS 11.1 Laws of Thermodynamics 11.2 Pure Substances 141.3 Gas Mixtures and Ideal Gases 161.4 Maxwell’s Relations and TdS–Equations 191.5 Vapour Power Cycles/Gas Power Cycles/Refrigeration Cycles 211.6 Psychometry Fundamentals 31

Questions 37

Chapter-2 INTERNAL COMBUSTION ENGINES AND NUCLEARPOWER PLANTS 39

2.1 Fuels for I.C. Engines and Combustion 392.2 Theory of Simple Carburetor 492.3 Power Output of Engine (I.C. Engines) 512.4 Nuclear Power Plants Principles and Types 542.5 Fuels and Combustion 56

Questions 58

Chapter-3 STEAM BOILERS, ENGINES, NOZZLES AND TURBINES 593.1 Boilers 593.2 Steam-Engines 633.3 Steam Condensers 663.4 Steam Nozzles 673.5 Steam Turbines 71

Questions 77

Chapter-4 COMPRESSORS, GAS TURBINES AND JET PROPULSION 794.1 Compressors 794.2 Flow Through Nozzles – Shock Properties 884.3 Gas Turbines 904.4 Jet Propulsion 98

Questions 103

Chapter-5 HEAT TRANSFER 1045.1 Heat Conduction 1045.2 Heat Transfer by Convection 1145.3 Heat Transfer with Change of Phase 117

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5.4 Thermal Radiation 1195.5 Heat Exchangers 125

Questions 128

Chapter-6 FLUID-MECHANICS AND HYDRAULIC MACHINES 1306.1 Properties of Fluids 1306.2 Fluid Statics 1316.3 Fluid Kinematics 1376.4 Fluid Dynamics 1396.5 Laminar Flow 1436.6 Turbulent Flow 1466.7 Flow Through Pipes 1476.8 Dimensional Analysis 1486.9 Boundary Layer 150

6.10 Immersed Bodies 1526.11 Compressible Flow 1536.12 Open Channel Flow 1556.13 Hydraulic Turbines 1576.14 Hydraulic Pumps 1626.15 Hydraulic Systems 167

Questions 167

Chapter-7 THEORY OF MACHINES 1697.1 Simple Mechanisms 1697.2 Velocity and Acceleration Analysis in Mechanisms 1707.3 Mechanisms with Lower Pairs—Path Generation 1727.4 Friction (Screw Friction) 1777.5 Belt-Rope-Chain Drives 1817.6 Gears-‘Gear-Trains’ 1847.7 Gear Trains 1897.8 Gyroscopic Couple 1917.9 Inertia Forces in Reciprocating Parts 195

7.10 Fly Wheels 1997.11 Governors 2017.12 Cams and Followers 2077.13 Balancing of Inertia Forces and Moments in Machines 2137.14 Vibration in Mechanical Systems 220

Questions 228

Chapter-8 MACHINE DESIGN 2298.1 Variable Stresses in Machine Parts 2298.2 Design of Pressure Vessels 2328.3 Riveted Joints 234

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8.4 Welded Joints 2378.5 Screwed Joints 2408.6 Cotter and Knuckle Joints 2468.7 Keys and Couplings 2498.8 Power Screws 2538.9 Belt-Drives and Ropes 256

8.10 Fly-Wheel 2608.11 Springs 2618.12 Clutches 2668.13 Brakes 2688.14 Bearings 2718.15 Design of Gears 275

Questions 281

Chapter-9 STRENGTH OF MATERIALS 2839.1 Simple Stresses 2839.2 Complex Stresses and Mohr’s Circle 2859.3 Shear Force and Bending Moment Diagrams 2879.4 Stresses in Beams : Bending Stresses in Beams 2889.5 Deflection of Beams 2919.6 Torsion of Circular Shafts 3009.7 Buckling of Columns and Struts 3029.8 Trusses 3059.9 Cylinders and Curved Beams 306

9.10 Theories of Failure 310Questions 316

Chapter-10 METALLURGY AND ENGINEERING MATERIALS 31710.1 Metals and Alloys 31710.2 Alloy Steels 32010.3 Tool Steels 32110.4 Cast Irons 32210.5 Non-Ferrous Metals and Alloys 32210.6 Heat Treatment 32510.7 Plastics and Other Materials 32910.8 Other Important Materials in Engineering 33110.9 Basic Concepts on Structure of Solids 334

10.10 Crystal Imperfections 33510.11 Alloys and Binary Phase Diagrams 339

Questions 342

Chapter-11 PRODUCTION TECHNOLOGY 34311.1 Mechanics of Metal Cutting 34311.2 Machining Operations 349

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11.3 Forming Processes 36011.4 Welding 36911.5 Casting Processes 37411.6 Numerically Controlled (NC) Tools 38311.7 Jigs and Fixtures 38411.8 Miscellaneous Topics 38611.9 Elements of Metrology 390

Questions 395

Chapter-12 INDUSTRIAL ENGINEERING 39712.1 Work Study 39712.2 Production Planning and Control 40712.3 Design of Production System and Product Cost Principles of

Plant Layout 41212.4 Inspection : Quality Control 41612.5 Network Analysis 41912.6 Operations Research 42112.7 Material Handling 428

Questions 429

EXAMPLES 432

APPENDIX 499

INDEX 504

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PREFACE TO THE SECOND EDITION

In this revision, many typographical errors are corrected and many worked-

out examples are included. Wherever appropriate, the theory is also enhanced.

PREFACE TO THE FIRST EDITION

In the field of Mechanical Engineering, there is a continuous demand for a

concise and compact book, which can serve as a reference book for students preparing

for degree and diploma as well as for practicing engineers. This book has beenwritten to this demand; while preparing the material for this book, I have constantly

kept in mind the latest requirements of the students of Indian University examinations.

Whole subject has been split up into twelve main headings and each chapterconcludes with few typical problems, which can be easily attempted with the

theory provided in the book. Solved examples provided at the end of the book help

in understanding the concepts more thoroughly. Available specialized books inmarket including objective type books may not cater to these demands. This book

is thus an updated compendium of terms used in Mechanical Engineering discipline.

Suggestions and feedback regarding typographical errors are always cherishedfrom readers and are gratefully acknowledged. Finally I would like to thank the

publishers in bringing the book in nice format.

—Author

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1

1. THERMODYNAMICS

BASIC CONCEPTS

Thermodynamics is the science of energy transfer and its effect on physical propertiesof substances.

An open system is one in which both mass and energy transfer occurs. In a closedsystem only energy transfer takes places while in an isolated system neither mass norenergy transfer occurs.

Intensive property of a thermodynamic system is one, which is independent of mass ofthe system. Examples include pressure, temperature, specific energy and specific volume.Extensive property is related to mass. e.g., volume, velocity, energy etc.

If there is a flow of mass into and out of the system, attention is focussed on a certainvolume in space, surrounding the system and is known as control volume bounded by asurface called the control surface (see Fig. 1.1).

The matter and energy can cross the control surface. In the case of a device involvinga flow of mass or energy control volume is specified, while dealing with a fixed quantity ofmass the system approach is followed. Thus, these two approaches are equivalent to openand closed system respectively.

M Compressor

Air

Control-volume

Control surface

Fig. 1.1

1.1 LAWS OF THERMODYNAMICS

When a system exists in equilibrium is separated from its surroundings by a diathermicwall (which allows heat to flow) and if there is no spontaneous change in any property of thesystem the system is said to exist in thermal equilibrium state. A process which is the locusof all the equilibrium points passed through by the system is known as quasi-static process.Infinite slowness is the characteristic feature of a quasi-static process.

The basis of temperature measurement is given by the Zeroth law of thermodynamics.A quantitative meas are of temperature is obtained by using a reference body and a physicalcharacteristic of the body.

2 HANDBOOK OF MECHANICAL ENGINEERING

Zeroth law of thermodynamics states that if two bodies are in thermal equilibrium witha third body, they are also in thermal equilibrium with each other.

Ideal gas temperature T at a pressure ‘p’ is defined by T = 273.16 Limppp tt→0

, where ptis pressure at triple point.

According to the first law total energy of the system remains constant. Mathematically :(a) First law for a closed system undergoing a cycle (∑W)cycle = J(∑Q)cycle or “dW = J.

“dQ, where J is Joule’s equivalent (= 4.187 kJ).(b) First law for a closed system undergoing a change of state :

Q-W = ∆E = increase in energy of system(c) First law for open system : specific energy of the system remains constant

i.e., h gddm1

12

1C2

ZQ

+ + +FHG

IKJ = h g

ddm2

22

2C2

ZW

+ + +FHG

IKJ

this is also called Specific flow energy equation (S.F.E.E.)where h is enthalpy, C is velocity, Z is elevation, and g is gravitational constant.

Example 1.1. Air contained in a cylinder comprises a system. A cycle is completed asfollows : (a) Piston does 85 kJ of work on air during its compression stroke while 42 kJ ofheat is rejected to the surroundings which is mainly water in the jackets.

(b) On expansion stroke air does 120 kJ of work ion the piston. Determine the quantityof heat added to the system.

Solution : During the process (a) from first law of thermodynamics Q = W + ∆E∴ ∆E = Q − W = − 42 − (− 85)

= 43 kJIn the second process (b) again

Q = W + ∆E= 120 + (− 43) (Since end conditions are reversed ∆E = − 43)= 77 kJ.

Mathematical Expressions for Work

(a) Work and heat are path functions, i.e., dW ≠ − −z W W = W or W2 1 2 21

2

1

(b) Types of work :(i) Electrical work = I.V. Joules, I is current, V is voltage.

(ii) Shaft work = 2Π NT Nm/min, N is speed, T is torque.(iii) Paddle work (stirring work) dW.(iv) Flow work : = p1 V 1 per unit mass(v) Stretching wire work : dW = – T x dL. Here T is tension and dL is elongation.

(vi) Changing surface film dW = σdAA

A

1

2z , σ is surface tension of the film.(c) Free expansion is an irreversible process. Here work done dW = 0 even pdv ≠ 0.

THERMODYNAMICS 3

Energy is a property of a system and is a point function. Total energy is sum of internalenergy, kinetic energy and potential energies, i.e., E = U + Ek + Ep.

Specific heat at constant volume Cv is defined as the rate of change of specific internalenergy (u) with respect to temperature (T) when the volume is held constant. Mathematically

Cv = ∂∂u

vTFHGIKJ

Enthalpy of a substance is defined as h = (u + pV)Specific heat at constant pressure CP is defined as the rate of change of specific enthalpy

(h) with respect to temperature (T) when pressure is held constant. Mathematically

Cp = ∂∂u

pTFHGIKJ

Note : Cp, Cv are properties of the system.

A machine, which continuously supplies mechanical work without some other form ofenergy disappearing simultaneously, is called perpetual motion machine of first kind(PMM1) [Fig. 1.2].

Fig. 1.2

Perfect gas obeys all the gas laws under all conditions of pressure and temperature.Perfect gas relations for typical thermodynamic processes are often necessary in

computing cycle data such as work, heat, internal energy etc. Table 1.1 shows each of thequantities in different processes. The concept of entropy will be given at the end of secondlaw of thermodynamics.

Table 1.1

Quantity Constant Isobaric Isothermal Isentropic Polytropicvolume process process process process

(isochoricprocess)

Work 0 p(V2 − V1) p1 V1 ln VV

2

1

p p1 1 2 2V Vl

−−γ

=p p

n1 1 2 2V V−

−( )1

1. pdv1

2

z Cv (T1 − T2) = γ −−LNM 11n ×Cv(T1 − T2)]

2. Internal Cv (T2 – T1) Cv(T2 – T1) 0 Cv (T2 – T1) Cv (T2 – T1)energy(U2 – U1)

Q → PMM1 → W

Handbook of Mechanical Engineering

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