1

Introduction

1.1 DEFINITION

The turbomachine is an energy conversion device, converting mechanical energy tothermal/pressure energy or vice versa. The conversion is done through the dynamicinteraction between a continuously flowing fluid and a rotating machine component.Both momentum and energy transfer are involved. Hence, positive-displacementmachines, such as piston-type or screw-type machines, which operate as a result ofthe static interaction between the fluid and mechanical components, are excluded.

A turbomachine has a rotating component that provides continuous interactionwith a flowing fluid. Mechanical energy is delivered through this rotating element.Thermal/pressure energy in the flowing fluid can be in either a kinetic energy or staticenthalpy energy mode. These two modes of energy can be converted in either directionthrough a diffuser or nozzle, which are called stators, while rotating components arecalled rotors or impellers. Additional components are sometimes needed to direct thefluid into an appropriate direction.

1.2 TYPES OF TURBOMACHINES

Turbomachines can be classified according to

(a) direction of energy transfer, either from mechanical to thermal/pressure or viceversa;

1

COPYRIG

HTED M

ATERIAL

2 Introduction

(b) type of fluid medium handled, either compressible or incompressible; and(c) direction of flow through the rotating impeller—it can be in axial, radial, or

mixed with respect to the rotational axis.

A classification is presented in Table 1.1. In terms of the direction of energy transfer,the machine can be either a pumping device or a turbine. A pumping device convertsmechanical energy into thermal/pressure energy. Examples of such devices are liquidpumps, compressors, blowers, or fans. The gas-handling devices are classified based ontheir discharge pressure and will be discussed in detail in later chapters. A turbine con-verts thermal/pressure energy to mechanical energy. Common examples are hydraulicturbines, wind turbines, and gas or steam turbines.

Among these machines, the fluid medium handled by the liquid pump, hydraulicturbine, fan, and wind turbine can be treated as an incompressible fluid. Hence thechange of thermodynamic properties, other than pressure, of these fluids can be ignored.In machines that handle gas or steam, the variation of thermodynamic properties, suchas temperature, pressure, and density, has to be incorporated into flow and energytransfer analysis.

Depending on the direction of flow in the impeller, with respect to its rotating axis,the machines can be classified as radial-, mixed-, and axial-flow machines, as shown inFigure 1.1. The Francis type has the majority of flow in the mixed direction, except thatat discharge. In addition, the radial- and mixed-flow impellers can be closed, semiopen,or open type as shown.

Table 1.1 Classification of Turbomachines

Fluid Machines

Turbomachines

Directionof energytransfer

Pumpingdevices

Type offluid(liquid/gas)

Flowdirection

Mechanicalarrangement

Positive-displacementmachines

Others

Turbines

Hydraulic, wind,gas, steam turbines

Pump, fan, blower,compressor

Axial-flow, mixed-flow, radial-flow

Horizontal- or vertical-axis pump,single- or double-suction pump/fan,single- or multistage pump/compressor,backward-, radial-, or forward-vane fan,full- or partial-admission turbine, horizontal-or vertical-axis wind turbine

1.3 Applications of Turbomachines 3

Radial Francis

Meridional view (from Ref. 1-1)

(from Ref. 1-2)

Open impeller Semiopen impeller Closed impeller

Mixed flow Propeller

Figure 1.1 Types of turbomachines according to impeller type and flow direction throughimpeller. [Reprinted by permission from (a) Stepanoff, A. J., Centrifugal and Axial Flow Pumps ,2nd ed., John Wiley & Sons, Inc. New York, 1957; (b) Gibbs, C. W. (Ed.), Compressed Air andGas Data , 2nd ed., Ingersoll-Rand Co., Phillisburg, NJ,1971.]

Further classification of turbomachines according to their mechanical arrangementis also possible. This includes the basic single stage or the combinations of multistage,single suction or double suction, horizontal or vertical axis, and so on. Examples of thedifferent types of arrangements are shown in Figure 1.2. These arrangements are chosenfrom a consideration of compactness or convenience of installation and maintenance.

Other classifications are made based on inlet flow arrangements, such as full admis-sion or partial admission, or on the flow process in the rotor, either impulse (constantstatic enthalpy or pressure) or reaction machine. These classifications will be discussedin detail in later chapters when the individual types of machine are treated.

1.3 APPLICATIONS OF TURBOMACHINES

Turbomachines are widely used in power-generating and fluid-handling systems. In atypical central power plant, fossil or nuclear, as the one shown in Figure 1.3,5 thecentral component is a steam turbine, which is used to convert the thermal energy ofsteam into mechanical energy to drive an electric generator. Several types of pumps areemployed to handle liquid water, including boiler-feed pump, condensate pump, andcooling-water circulating pump. Turbomachines are also employed in other energy-producing systems such as hydropower, wind power, and geothermal power install-ations.

The other major application of turbomachines is in the gas turbine engines used inaircraft and industrial power plants. Multistage axial-flow gas turbines and compressorsare exclusively used in high-power units. Centrifugal types are used in the smallerengines of propulsion systems for ground, marine and air vehicles. A typical case

4 Introduction

(a) Single-stage, single-suction blower (b) Multistage horizontal compressor

(c) Double-suction pump (d) Vertical pump

Strainer

Well

Bowl assembly

Column assembly

Pipe coupling

Gatevalve

Driver

Dischargehead

Figure 1.2 Types of turbomachines according to mechanical arrangements. [Reprinted by per-mission from (a & b) Gibbs, C.W. (Ed.), Compressed Air and Gas Data, 2nd ed. Ingersoll-RandCo. Phillisburg, New Jersey 1971; (c) Karassik, I.J. & et al. (Eds.r) Pump Handbook , McGraw-Hill, Inc., New York 1976; (d ) Turbine Data Handbook, 1st ed. Weir Floway, Inc. Fresno, CA1987.]

1.3 Applications of Turbomachines 5

Figure 1.3 Typical central power plant with combined cycle. (Courtesy of Mechanical Engi-neering Power magazine, Nov. 1997, page 2; c© Mechanical Engineering magazine, the AmericanSociety of Mechanical Engineers.)

Radial-inflowturbine

Radialcompressor

Figure 1.4 Automotive gas turbine engine. (Reprinted by permission from Garrett/FordAGT101 Advanced Gas Turbine Program Summary , Garrett Turbine Engine Co., HoneywellAerospace, Phoenix, AZ.)

is the automotive engine shown in Figure 1.4.6 In the fluid-handling systems foundin many industries, the different types of pumps, fans, blowers, and compressors areemployed to pressurize and transport the liquid or gas. Typical examples are in theheating, ventilation, and air-conditioning (HVAC) system shown in Figure 1.57 andwater supply, water treatment, irrigation, oil production, oil refinery, gas transport,chemical process, and many other industries.

6 Introduction

Fueland air

Fueland air

Flue

Hot-waterpumpCondenser

Hot-water supply and return

Chilled water

Chillerelectric orstream driven

Chilled-waterreturn

Chilled-watersupplyChilled-water

pumpCondensing-water pump

Coolingtower

Air-cooledchiller

Condensing-watersupply and return

Alternate chilled-water system

Alternatehot-watersystem

Air-conditioning anddistribution system

Exhaustair

FilterHeat coil

Cool coil

Supplyfan

Humidifier

Supplyair tozone

Return airfrom zone

Returnair fan

To other airhandlers

To other airhandlers

Steam Converter

Hotwater

Outdoor air

Condensatereturn

Burnerassembly

Hot-waterboiler

Steamboiler

Figure 1.5 Turbomachines used in a typical commercial HVAC system. (Reprinted by permission from McQuis-ton, F. C., Parker, J. D. & Spitler, J. D., Heating, Ventilating & Air Conditioning , 6th ed., John Wiley & Sons, Inc.New York, 2005.)

1.4 PERFORMANCE CHARACTERISTICS

As an energy conversion device, a turbomachine is characterized with several param-eters. These parameters and their relationship with machine geometry and dimensionsbased on the principles of fluid mechanics and thermodynamics are the main topics inthis text.

The main parameters that characterize a turbomachine are input and output power,rotating speed, efficiency, through flow rate and inlet, outlet fluid properties, and so on.In pumping devices such as liquid pumps, fans, or compressors, the output pressureis used to overcome the friction loss in the load, which is characterized with pressureloss versus flow rate. Hence the performance of a typical pumping device is expressedin terms of the pressure rise �p (or head rise H ) versus the volumetric flow rate Q, ormass flow rate m , at a constant rotating speed N, as shown in Figure 1.6. The operatingcondition is varied with a throttle valve at the discharge. In most cases, the input shaftpower and efficiency are also included in this diagram. The overall efficiency is defined

1.4 Performance Characteristics 7

Flow rate, Q, m

N1

N1

N2

N2

N3

N3

Pre

ssur

e ris

e, ∆

PP

ress

ure

ratio

, P2/

P1

Sha

ft po

wer

, Ps

Figure 1.6 Typical pump, fan, and compressor performance curves at constant rotating speed.

as the ratio of output power to input shaft power:

η = Po

Ps

, (1.1)

where Po is the output hydraulic power (product of volumetric flow rate and pressurerise) and Ps is the shaft power (product of angular velocity and torque of the shaft),that is,

Po = Q �p and Ps = ωτ .

For a fan or blower, the pressure rise is expressed in terms of the water head, eithertotal or static head, and the flow rate is expressed in terms of the volumetric flow rateat the inlet, since the density can vary slightly. In a compressor, the performance isnormally expressed in terms of the outlet–inlet pressure ratio p2/p1 versus the massflow rate at a constant rotating speed. The adiabatic efficiency is expressed as the ratioof ideal enthalpy increase along the isentropic process over the actual enthalpy increase,that is, ηad = �hs/�h.

At the high flow rate, the operation is limited by cavitation in pumps and chokingdue to shock waves in compressors. At the low flow rate, it is limited by surging, whichis a strong flow reversal at the inlet due to boundary layer separation. This problem ismore severe in a compressor than in a pump.

The performance of turbines is also expressed in terms of head, rotating speed,output shaft power, efficiency, and discharge flow rate. The loads, such as an electricgenerator or other mechanical machinery, are characterized by the input shaft powerversus the rotating speed. Hence the basic turbine performance curve is plotted in termsof the output torque or shaft power versus the rotating speed, as shown in Figure 1.7.The head or inlet condition is usually fixed and is a function of the hydraulic instal-lation or the combustion chamber condition for the gas/steam turbine. The regulationis obtained by varying the flow rate by means of the gate or nozzle position. With agiven inlet condition, the rotating speed is varied by adjusting the load. In practice,

8 Introduction

Rotating speed, N

Q1

Q2

Q3

Sha

ft po

wer

, Ps

Tor

que,

τ

Figure 1.7 Typical basic performance curves of a turbine (torque and shaft power versus rotat-ing speed at constant inlet condition).

N = const

Load (%)

100

Effi

cien

cy (

%)

Figure 1.8 Turbine performance in terms of efficiency versus load (with constant rotatingspeed).

sometimes turbines are required to drive a constant-speed machine with variable load.Hence, a performance diagram of efficiency versus load with a constant rotating speedis also frequently provided, as shown in Figure 1.8. Detailed discussion of these curveswill be covered in later chapters.

1.5 METHOD OF ANALYSIS

The flow through a typical turbomachine is normally three dimensional and turbulentand is either compressible or incompressible. Occasionally, the fluid medium can bea two-phase or two-component mixture of liquid, vapor, gas, and solid particles. Dueto these complicated flow processes, especially inside the rotating impeller, analysisbased on the first principles of three-dimensional fluid mechanics and thermodynamics

1.5 Method of Analysis 9

is more difficult and requires a numerical method with a computer in most cases. Inthis entry-level treatment, the basic physical processes will be emphasized with thesimplified one-dimensional or integral form of flow analysis.

Dimensional analysis is widely used in the study of turbomachines. Specifically,the results of dimensional analysis can be applied to the correlation of experimentaltest data and to scale up the model test results to predict the prototype performance.Detailed procedures and the applications of dimensional analysis to turbomachines willbe discussed in the next chapter.

For a completely new design, preliminary analysis still has to be performed basedon fluid mechanics and thermodynamics principles with some simplifications. Theenergy transfer equation, the so-called Euler equation to relate the energy transferrate between the flowing fluid and the rotating impeller of a turbomachine, can bederived from the momentum equation of fluid mechanics. The momentum equationis expressed in integral form applied to the control volume enclosing the impeller, asshown in Figure 1.9. The Euler equation relates the rate of mechanical energy input oroutput of the shaft with the flow properties and geometric dimensions at the inlet andoutlet of the impeller. The losses due to friction and three-dimensional effects throughflow passages have to be estimated empirically. These two types of analyses for variouskinds of turbomachines will be discussed in detail in the next two chapters. The flowprocesses in turbomachines can be treated as either the internal flow in a channel orthe external flow over an airfoil, depending on the type of machine. In radial- andmixed-flow machines, the flow passages are relatively long, and internal flow mod-els are used. In axial-flow machines, external flows over airfoils with the interferencefactor included are appropriate.

In more advanced analyses, a quasi three-dimensional flow analysis has beenaccomplished for the design operating condition. However, under off-design condi-tions, most of the analyses are still empirical or semiempirical in nature. In recentyears, CFD (computational fluid dynamics) software has become available and afford-able for the design and analysis of various types of turbomachines.8 Detailed flowanalyses at different parts of the machine can be performed before the final design isfixed. A brief discussion of this topic is given in Appendix C.

Example 1.1E

A centrifugal pump is used to pump the oil with a specific gravity (s.g.) of 0.72. Itrequires 20.5 hp of shaft power when the flow rate is 385 gpm with an efficiency of

Figure 1.9 Control surface enclosing an impeller.

10 Introduction

83%. Determine the pressure rise in terms of pounds per square inch, head of waterand head of oil pumped.

SOLUTION From

Ps = 20.5 hp = 20.5 × 550 = 11,275 ft-lbf/s,

Q = 385 gpm = 385

449= 0.857 ft3/s, η = Q�p

Ps

,

we have

�p = ηPs

Q= 0.83 × 11,275

0.857 × 144= 75.8 psi.

Also from �p = ρg �H, we have

�Hw = 75.8 × 144

62.4= 175 ft of water,

�Hoil = �Hw

s.g.= 175

0.72= 243 ft of oil.

Example 1.1S

A centrifugal pump is used to pump the oil with a specific gravity of 0.72. It requires15.3 kW of shaft power when the flow rate is 87.4 m3/h with an efficiency of 83%.Determine the pressure rise in terms of kilopascals (kPa), head of water and head ofthe oil pumped.

SOLUTION From Ph ≡ Q �p = ηPs , we have

�p = ηPs

Q= 0.83 × 15.3 × 1000

87.4/3600(N-m/s)/(m3/s)

= 523 × 103 N/m2 = 523 kPa.

Also from �p = ρg �H, we have

�Hw = 523 × 1000

998 × 9.81(N/m2)/[(kg/m3)(m/s2)],

= 53.4 m of water,

�Hoil = �Hw

s.g.= 53.4

0.72= 74.2 m of oil.

Example 1.2E

A centrifugal fan delivers air of 12,000 cubic feet per minute (cfm) measured at theinlet to an air duct. If the total resistance of the duct system is 2.5 in. of water at thisflow rate and the total efficiency of the fan is estimated to be 85%, determine the shaftpower input to the fan in horsepower (the discharge area of the duct back to ambientatmosphere is 3.5 ft2).

1.5 Method of Analysis 11

SOLUTION The air flow velocity at discharge is V = 12,000/(60 × 3.5) = 57.14 ft/s;hence the dynamic head can be calculated from

ρaV2

2= 0.0762 × (57.14)2

32.2 × 2= 3.86 lbf/ft

2 = ρwgHv,

or Hv = 0.062 ft = 0.74 in. of water, or the total head Ht = 2.5 + 0.74 = 3.24 in. ofwater. So we have the shaft power:

Ps = Q �pt

ηt

= 12,000 × 3.24 × 62.4

60 × 12 × 0.85= 3964.2 ft-lbf/s = 7.2 hp.

Example 1.2S

A centrifugal fan delivers air of 340 cubic meters per minute (cmm) measured at theinlet to an air duct. If the total resistance of the duct system is 6.35 cm of water atthis flow rate and the total efficiency of the fan is estimated to be 85%, determine theshaft power input to the fan in kilowatts (kW) (the discharge area of the duct back toambient atmosphere is 0.325 m2).

SOLUTION The air flow velocity at discharge is V = 340/(60 × 0.325) = 17.4 m/s.Hence the dynamic head can be calculated from

ρaV2

2= 1.22 × 17.42

2(kg/m3)(m/s)2 = 184.7 N/m2 = 184.7 Pa.

Converting static pressure, we have �p = ρwgH = 998 × 9.81 × 0.0635 (kg/m3)(m/s2)m = 621.7 Pa and the total pressure �pt = 621.7 + 184.7 = 806.4 Pa. So wehave the shaft power:

Ps = Q�pt

ηt

= 340 × 806.4

60 × 0.85

= 5376 (m3/s)(N/m2) = 5.376 kW.

Example 1.3E

A hydropower site has a net head of 295 ft and available water flow capacity of 148 ft3/s.If a turbine rotating at 1800 rpm with an efficiency of 87% is to be installed, determinethe total output power and the torque.

SOLUTION From

�p = ρgH = 62.4 × 295 = 18,408 lbf/ft2 and Ps = ηQ �p,

we have

Ps = 0.87 × 148 × 18,408 = 2.37 × 106 lbf-ft/s = 4309 hp,

τ = Ps

ω= 2.37 × 106

1800 × 2π/60= 12.57 × 103ft-lbf.

12 Introduction

Example 1.3S

A hydropower site has a net head of 90 m and available water flow capacity of 4.2 m3/s.If a turbine rotating at 1800 rpm with an efficiency of 87% is to be installed, determinethe total output power and the torque.

SOLUTION From �p = ρgH = 998 × 9.81 × 90= 881,134 N/m2 and Ps = ηQ �p,we have

Ps = 0.87 × 4.2 × 881,134 = 3.22 × 106 N-m/s = 3220 kW,

τ = Ps

ω= 3.22 × 106

1800 × 2π/60= 17.1 × 103 N-m.

1.6 HISTORICAL EVOLUTION OF TURBOMACHINES

1.6.1 Water Pump

The development of modern turbomachines started in the eighteenth century. In 1705,Denis Papin published full descriptions of centrifugal blowers and pumps. But crudecentrifugal pumps were used in the United States until the early nineteenth century. In1839, W. D. Andrews added a volute, and in 1875, a vaned diffuser was added andpatented by Osborne Reynolds of England. It has been called “turbine pump” since then.

1.6.2 Blower/Compressor

In 1884, Charles Parsons patented an axial-flow compressor. Three years later, heproduced a three-stage centrifugal compressor for ship ventilation. In 1899, he madean 81-stage axial-flow compressor with 70% efficiency. But he had problems withthe axial-flow machines in the next few years and returned to making the centrifugalmachines in 1908. During this period, efforts on compressor development were alsocarried out by August Rateau in France. Continued work on compressor developmentwas primarily in gas turbine engine development.

1.6.3 Gas/Steam Turbines

The Greek geometrician Hero devised the first steam turbine in 62 a.d. A simpleclosed, spherical vessel mounted on bearings discharges steam from a boiler with oneor more pipes tangentially at the vessel’s periphery, as shown in Figure 1.10. He calledit Aeolipile (wind ball). It is a pure reaction machine. Much later, in 1629, Giovanni deBranca in Italy developed an impulse-type steam turbine similar to a horizontal waterwheel. (also shown in Figure 1.10).

In 1791, John Barber of Britain was granted the world’s first patent on the gasturbine, which consisted of all the elements of the modern gas turbine except thecompressor was a reciprocating type.

Not until the early nineteenth century did steam turbines attract any interest forpower generation. In 1831, William Avery in the United States produced Hero’s steam

1.6 Historical Evolution of Turbomachines 13

(a) Early reaction turbine (b) Early impulse steam turbine

Figure 1.10 Ancient steam turbines by Hero and Giovanni de Branca.

turbine to drive circular saws. In 1848, Robert Wilson of Scotland patented a radial-inflow steam turbine. In 1875, Osborne Reynolds of England, who invented the turbinepump, made a multistage axial-flow steam turbine running at 12,000 rpm. In 1884,Charles Parsons, also of England, made a multistage axial-flow reaction turbine runningat 18,000 rpm to produce 10 hp. He also tried but failed to produced a multistageradial-inflow turbine because of some mechanical problems. In the following few years,he devoted his effort to the further development of axial-flow machines. His machineswere used for marine propulsion and electrical power generation.

In the early stage of gas turbine engine development, the failure was mostly dueto the difficulty to design an efficient compressor (pumping liquid water in a steamturbine engine is easier). To produce a net positive output power, it requires that theturbine output power be greater than the power required by the compressor. This can beachieved by having either a higher efficient compressor or higher gas inlet temperatureto the turbine.

In 1903, Aegidus Eilling, in Norway, constructed the world’s first gas turbinethat produced net power output of 11 hp. His machine consisted of a 6-stage cen-trifugal compressor and a single-stage radial-inflow turbine. In France, August Rateau,in 1905, designed a gas turbine with total power output of 400 hp. It consisted of a25-stage centrifugal compressor with intercooling and a 2-stage axial-flow turbine ofimpulse type.

With the further development and improvement of the gas turbine, the followingmilestones of aviation have been achieved:

1. On August 27, 1939, the world’s first jet engine power flight of Heinkel He178 was successfully completed in Germany.

2. On July 27, 1949, the world’s first jet commercial airline, de Havilland Comet 1of England, made its first flight.

3. On May 25, 1953, the world’s first supersonic flight was made by the U.S. AirForce F-100 fighter plane.

4. On December 31, 1968, the first commercial supersonic flight was made byRussian TU-144, followed by British-French Concord flight on March 2, 1969.

In the past three decades, efforts have been made to increase the turbine inlettemperature with better materials and blade cooling. These efforts have resulted inthe thermal efficiency being increased from around 30 to 46% (GE’s CF6-80E enginewith turbine inlet temperature of 1370◦C in December 2003). Further improvement

14 Introduction

in thermal cycle efficiency can be achieved by combining the gas turbine and steamturbine in a combined-cycle plant.

1.6.4 Hydraulic Turbines

The Romans introduced the paddle-type water wheel, a pure impulse turbine, around70 b.c. for grinding grain. The study of water wheels with systematic modeling wasintroduced by the British experimenter John Smeaton in the eighteenth century. Heachieved a maximum efficiency of 60%.

In France, where there are more rivers, active development on water wheels wascarried out in the early-nineteenth century. In 1832, Benoit Fourneyron designed aradial-outflow machine to produce 50 hp with 85% efficiency. The activities moved tothe United States when Uriah Boyden added a vaneless radial diffuser to this type ofmachine and achieved 88% efficiency. In 1851, James Francis designed a radial-inflowturbine, which is known as the Francis turbine today. During the same period, JamesThomson in Britain worked on a more efficient radial-inflow turbine with a spiral inletcasing and adjustable inlet guide vanes.

1.6.5 Wind Turbine

Some simple versions of the windmill were used in Babylonia and China as early as2000 b.c. Hero of Greece also described the horizontal-axis windmill with sails asaerodynamic surfaces. By the twelfth century, the windmill was introduced to Europeby both Arabs and the Crusaders returning from the Near East. In the nineteenth century,small multibladed windmills were very popular for grain grinding and water pumpingin American farms.

In the 1970s, the U.S. Energy Research and Development Administration (the pre-decessor of the Department of Energy) launched a series of research-and-development(R&D) projects on wind turbines, with the power output ranging from 100 to 2000 kW.The results of these projects have provided a foundation for the design, production,and operation of today’s commercial wind turbines.

1.7 ORGANIZATION OF THE BOOK

The types of turbomachines classified in Table 1.1 can also be depicted in a three-dimensional coordinate system as follows:

Compressible fluid

Incompressible fluid

Axial flow

Turbine

Radial/mixed flow

Pumping device

4, 83, 7

1, 52, 6

Incompressible

Radial/mixed flow

1.7 Organization of the Book 15

Compressible flow analysis requires the usage of thermodynamic parameters andprocesses. Flow through a radial/mixed-flow machine is similar to the channel flow,while that through an axial-flow machine can be treated as the external flow overthe airfoils. The performance characteristics of a turbine are different from those of apumping device.

In the diagrams above each quadrant will represent a type of machine. Furthermore,each type of machine was developed by different groups of people and industry, andsome parameters are unique for a certain type of machine. Hence the presentation in aturbomachinery book is not straightforward and can be organized in several differentways, according to these three axes. Each way has its own merit.

Organization according to flow type is convenient for fluid dynamics researchersbut is confusing for entry-level readers. They are more familiar with the machinesaccording to the function (pumping devices or turbines) and the fluid medium handled(liquid or gas). So in this book, we start with a general discussion of all turbomachinesin the first three chapters. After that, the readers should be comfortable with the differentflow types. Then we proceed on to pumps and fans, both centrifugal and axial types,in Chapters 4 and 5 (quadrants 1, 2). With the low static pressure rise, axial-flow fanscan be treated as incompressible fluid machines. At the end of Chapter 5, the propeller,basically an open axial-flow pump or fan for producing thrust force, is briefly covered.

The review of thermodynamics in Appendix A can be used as reference. But itis recommended that at least the first five sections (A.1 to A.5) be reviewed beforecovering the centrifugal fan, blower, and compressor in Chapters 6 and 7 (quadrants3, 4). In Chapter 8, the axial-flow gas turbine is covered (quadrant 7). It is integratedwith a compressor in the gas turbine engine, which is a major topic in the study ofturbomachinery. Radial-inflow gas turbines (quadrant 8) are also covered in this chapter.They are used in the lower power engines. Axial-flow steam turbines (quadrant 7) arecovered in Chapter 9. Many concepts are similar to those of gas turbines. But someparameters and performance characteristics are different.

The hydraulic turbines, both axial-flow and radial-inflow types, and wind turbinesare presented in the last two chapters (quadrants 5, 6). They are receiving renewedinterest in recent years, because renewable energy is becoming an important part of theglobal energy picture due to the worry of global warming.

For each type of machine, the following items are covered:

1. Theory based on the simplified fluid mechanics principles (one dimensional orintegral form of equations)

2. Preliminary design procedure using basic theory and empirical formula/criteria(some of these sections can be skipped, depending on the instructors’ and stu-dents’ interest)

3. Ideal performance characteristics based on theory4. Actual performance characteristics with the modification due to loss mechanism

and other flow processes (sample curves/tables published by the manufacturersare included)

5. Engineering applications and machine selection procedure (some of thesesections can be read by the students themselves to save class time)

Since this book is primarily for entry-level readers, advanced topics on detaileddesign using a computer are not covered. However, a brief discussion of the application

16 Introduction

of CFD to turbomachine design is given in Appendix C and some references are citedfor those who want to pursue further studies on a particular machine or a design project.Also some web sites related to turbomachines are given.

Both International System (SI) and English system units are used in this book.Since turbomachinery is an applied subject, most of the information obtained fromindustry is in the English system, although the trend is moving toward SI. Detaileddiscussion on the dimensions and units are given in basic engineering texts. They arealso briefly discussed in Chapter 2. In the first three chapters, every example is workedout in both systems. After that, some are worked out in the English system, some in SI.

The prerequisite for using this book is a first course in fluid mechanics and ther-modynamics at the undergraduate level. For some schools, if the basic turbomachineryprinciples are covered in fluid mechanics, Chapters 2 and 3 and some sections inChapters 4 and 5 may be skipped or just briefly reviewed. Sections A.6 to A.10 inAppendix A are included for those students who plan to pursue more advanced studieson compressors and gas turbines.

REFERENCES

1. Stepanoff, A. J., Centrifugal and Axial Flow Pumps, John Wiley & Sons, New York, 1957.

2. Gibbs, C. W. (Ed.), Compressed Air and Gas Data, 2nd ed., Ingersoll-Rand Co., Phillisburg,NJ, 1971.

3. Karassik, I. J., Krutzsch, W. C., Fraser, W. H., and Messina, J. P. (Eds.), Pump Handbook,McGraw-Hill, New York, 1976.

4. Weir Floway, Inc., Floway Turbine Data Handbook, 1st ed., Weir Floway, Fresno, CA,1987.

5. Falcioni, J. G. (Ed.) ASME, Mechanical Engineering Supplement, American Society ofMechanical Engineers, New York, November 1997.

6. Garrett/Ford AGT101 Advanced Gas Turbine Program Summary, Garrett Turbine Engine Co.,Phoenix, AZ, 1985.

7. McQuiston, F. C., Parker, J. D., and Spitler, J. D., Heating, Ventilating & Air Conditioning,6th ed., John Wiley & Sons, New York, 2005.

8. CFD Software for turbomachine design: www.adapco.com; www.numeca.com; ConceptsNREC.com; Fluent.com etc.