A brief introduction to fluid mechanics 2nd EditionPDF电子书下载

1INTRODUCTION 1

1.1 Some Characteristics of Fluids 1

1.2 Dimensions, Dimensional Homogeneity, and Units 2

1.2.1 Systems of Units 5

1.3 Analysis of Fluid Behavior 7

1.4 Measures of Fluid Mass and Weight 7

1.4.1 Density 7

1.4.2 Specific Weight 8

1.4.3 Specific Gravity 9

1.5 Ideal Gas Law 9

1.6 Viscosity 11

1.7 Compressibility of Fluids 16

1.7.1 Bulk Modulus 16

1.7.2 Compression and Expansion of Gases 16

1.7.3 Speed of Sound 17

1.8 Vapor Pressure 19

1.9 Surface Tension 19

Problems 22

2 FLUID STATICS 27

2.1 Pressure at a Point 27

2.2 Basic Equation for Pressure Field 29

2.3 Pressure Variation in a Fluid at Rest 31

2.3.1 Incompressible Fluid 31

2.3.2 Compressible Fluid 34

2.4 Standard Atmosphere 34

2.5 Measurement of Pressure 35

2.6 Manometry 37

2.6.1 Piezometer Tube 37

2.6.2 U-Tube Manometer 38

2.6.3 Inclined-Tube Manometer 41

2.7 Mechanical and Electronic Pressure Measuring Devices 42

2.8 Hydrostatic Force on a Plane Surface 43

2.9 Pressure Prism 48

2.10 Hydrostatic Force on a Curved Surface 51

2.11 Buoyancy, Flotation, and Stability 53

2.11.1 Archimedes' Principle 53

2.11.2 Stability 55

2.12 Pressure Variation in a Fluid with Rigid-Body Motion 56

References 56

Problems 57

3 ELEMENTARY FLUID DYNAMICS—THE BERNOULLI EQUATION 67

3.1 Newton's Second Law 67

3.2 F = ma Along a Streamline 68

3.3 F = ma Normal to a Streamline 73

3.4 Physical Interpretation 75

3.5 Static, Stagnation, Dynamic,and Total Pressure 78

3.6 Examples of Use of the Bernoulli Equation 81

3.6.1 Free Jets 81

3.6.2 Contined Flows 82

3.6.3 Flowrate Measurement 89

3.7 The Energy Line and the Hydraulic Grade Line 93

3.8 Restrictions on the Use of the Bernoulli Equation 96

Problems 97

4 FLUID KINEMATICS 105

4.1 The Velocity Field 105

4.1.1 Eulerian and Lagrangian Flow Descriptions 107

4.1.2 One-, Two-, and Three-Dimensional Flows 108

4.1.3 Steady and Unsteady Flows 109

4.1.4 Streamlines, Streaklines,and Pathlines 109

4.2 The Acceleration Field 114

4.2.1 The Material Derivative 114

4.2.2 Unsteady Effects 116

4.2.3 Convective Effects 117

4.2.4 Streamline Coordinates 118

4.3 Control Volume and System Representations 119

4.4 The Reynolds Transport Theorem 120

4.4.1 Derivation of the Reynolds Transport Theorem 121

4.4.2 Physical Interpretation 126

4.4.3 Selection of a Control Volume 127

References 127

Problems 127

5FINITE CONTROL VOLUME ANALYSIS 132

5.1 Conservation of Mass—The Continuity Equation 132

5.1.1 Derivation of the Continuity Equation 132

5.1.2 Fixed, Nondeforming Control Volume 134

5.1.3 Moving, Nondeforming Control Volume 139

5.2 Newton's Second Law—The Linear Momentum and Moment-of-Momentum Equations 141

5.2.1 Derivation of the Linear Momentum Equation 141

5.2.2 Application of the Linear Momentum Equation 142

5.2.3 Derivation of the Moment-of-Momentum Equation 156

5.2.4 Application of the Moment-of-Momentum Equation 157

5.3 First Law of Thermodynamics—The Energy Equation 166

5.3.1 Derivation of the Energy Equation 166

5.3.2 Application of the Energy Equation 169

5.3.3 Comparison of the Energy Equation with the Bernoulli Equation 172

5.3.4 Application of the Energy Equation to Nonuniform Flows 179

Problems 182

6DIFFERENTIAL ANALYSIS OF FLUID FLOW 196

6.1 Fluid Element Kinematics 197

6.1.1 Velocity and Acceleration Fields Revisited 197

6.1.2 Linear Motion and Deformation 198

6.1.3 Angular Motion and Deformation 199

6.2 Conservation of Mass 203

6.2.1 Differential Form of Continuity Equation 203

6.2.2 Cylindrical Polar Coordinates 205

6.2.3 The Stream Function 206

6.3 Conservation of Linear Momentum 210

6.3.1 Description of Forces Acting on Differential Element 211

6.3.2 Equations of Motion 213

6.4 Inviscid Flow 214

6.4.1 Euler's Equations of Motion 214

6.4.2 The Bernoulli Equation 215

6.4.3 Irrotational Flow 217

6.4.4 The Bern oulli Equation for Irrotational Flow 218

6.4.5 The Velocity Potential 218

6.5 Some Basic, Plane Potential Flows 223

6.5.1 Uniform Flow 224

6.5.2 Source and Sink 225

6.5.3 Vortex 227

6.5.4 Doublet 231

6.6 Superposition of Basic, Plane Potential Flows 233

6.6.1 Source in a Uniform Stream—Half-Body 233

6.6.2 Flow Around a Circular Cylinder 238

6.7 Other Aspects of Potential Flow Analysis 244

6.8 Viscous Flow 244

6.8.1 Stress-Deformation Relationships 244

6.8.2 The Navier-Stokes Equations 246

6.9 Some Simple Solutions for Viscous,Incompressible Fluids 247

6.9.1 Steady, Laminar Flow Between Fixed Parallel Plates 247

6.9.2 Couette Flow 250

6.9.3 Steady, Laminar Flow in Circular Tubes 253

6.10 Other Aspects of Differential Analysis 255

References 256

Problems 256

7SIMILITUDE, DIMENSIONAL ANALYSIS, AND MODELING 265

7.1 Dimensional Analysis 265

7.2 Buckingham Pi Theorem 267

7.3 Determination of Pi Terms 268

7.4 Some Additional Comments About Dimensional Analysis 274

7.4.1 Selection of Variables 274

7.4.2 Determination of Reference Dimensions 275

7.4.3 Uniqueness of Pi Terms 275

7.5 Determination of Pi Terms by Inspection 276

7.6 Common Dimensionless Groups in Fluid Mechanics 277

7.7 Correlation of Experimental Data 278

7.7.1 Problems with One Pi Term 279

7.7.2 Problems with Two or More Pi Terms 280

7.8 Modeling and Similitude 283

7.8.1 Theory of Models 283

7.8.2 Model Scales 287

7.8.3 Distorted Models 288

7.9 Some Typical Model Studies 289

7.9.1 Flow Through Closed Conduits 289

7.9.2 Flow Around Immersed Bodies 291

7.9.3 Flow with a Free Surface 294

References 296

Problems 296

8VISCOUS FLOW IN PIPES 304

8.1 General Characteristics of Pipe Flow 304

8.1.1 Laminar or Turbulent Flow 305

8.1.2 Entrance Region and Fully Developed Flow 307

8.2 Fully Developed Laminar Flow 308

8.2.1 From F = ma Applied to a Fluid Element 308

8.2.2 From the Navier-Stokes Equations 313

8.3 Fully Developed Turbulent Flow 313

8.3.1 Transition from Laminar to Turbulent Flow 313

8.3.2 Turbulent Shear Stress 314

8.3.3 Turbulent Velocity Profile 315

8.4 Dimensional Analysis of Pipe Flow 316

8.4.1 The Moody Chart 316

8.4.2 Minor Losses 321

8.4.3 Noncircular Conduits 329

8.5 Pipe Flow Examples 331

8.5.1 Single Pipes 331

8.5.2 Multiple Pipe Systems 341

8.6 Pipe Flowrate Measurement 342

References 347

Problems 347

9FLOW OVER IMMERSED BODIES 355

9.1 General External Flow Characteristics 355

9.1.1 Lift and Drag Concepts 356

9.1.2 Characteristics of Flow Past an Object 360

9.2 Boundary Layer Characteristics 363

9.2.1 Boundary Layer Structure and Thickness on a Flat Plate 363

9.2.2 Prandtl/Blasius Boundary Layer Solution 365

9.2.3 Momentum Integral Boundary Layer Equation for a Flat Plate 366

9.2.4 Transition from Laminar to Turbulent Flow 370

9.2.5 Turbulent Boundary Layer Flow 372

9.2.6 Effects of Pressure Gradient 375

9.3 Drag 378

9.3.1 Friction Drag 379

9.3.2 Pressure Drag 379

9.3.3 Drag Coefficient Data and Examples 380

9.4 Lift 395

9.4.1 Surface Pressure Distribution 395

9.4.2 Circulation 399

References 400

Problems 401

10OPEN-CHANNEL FLOW 409

10.1 General Characteristics of Open-Channel Flow 409

10.2 Surface Waves 410

10.2.1 Wave Speed 410

10.2.2 Froude Number Effects 413

10.3 Energy Considerations 413

10.3.1 Specific Energy 414

10.4 Uniform Depth Channel Flow 416

10.4.1 Uniform Flow Approximations 416

10.4.2 The Chezy and Manning Equations 417

10.4.3 Uniform Depth Examples 418

10.5 Gradually Varied Flow 425

10.6 Rapidly Varied Flow 426

10.6.1 The Hydraulic Jump 426

10.6.2 Sharp-Crested Weirs 431

10.6.3 Broad-Crested Weirs 433

10.6.4 Underflow Gates 437

References 438

Problems 438

11TURBOMACHINES 445

11.1 Introduction 446

11.2 Basic Energy Considerations 447

11.3 Basic Angular Momentum Considerations 450

11.4 The Centrifugal Pump 452

11.4.1 Theoretical Considerations 452

11.4.2 Pump Performance Characteristics 456

11.4.3 System Characteristics and Pump Selection 459

11.5 Dimensionless Parameters and Similarity Laws 462

11.5.1 Specific Speed 466

11.6 Axial-Flow and Mixed-Flow Pumps 467

11.7 Turbines 469

11.7.1 Impulse Turbines 470

11.7.2 Reaction Turbines 477

11.8 Compressible Flow Turbomachines 481

References 482

Problems 482

A UNIT CONVERSION TABLES 490

B PHYSICAL PROPERTIES OF FLUIDS 494

C PROPERTIES OF THE U.S.STANDARD ATMOSPHERE 500

ANSWERS 502

INDEX 507