Chapter 14 : Turbomachinery - Notes, Chemical, Engineering, Semester Chemical Engineering Notes | EduRev

 Page 1


 
 
 
 
 
 
 
 
 
 
 
 
 
PROPRIETARY AND CONFIDENTIAL 
 
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beyond the limited distribution to teachers and educators permitted by McGraw-Hill 
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Page 2


 
 
 
 
 
 
 
 
 
 
 
 
 
PROPRIETARY AND CONFIDENTIAL 
 
This Manual is the proprietary property of The McGraw-Hill 
Companies, Inc. (“McGraw-Hill”) and protected by copyright and other 
state and federal laws.  By opening and using this Manual the user 
agrees to the following restrictions, and if the recipient does not agree 
to these restrictions, the Manual should be promptly returned unopened 
to McGraw-Hill:  This Manual is being provided only to authorized 
professors and instructors for use in preparing for the classes using 
the affiliated textbook.  No other use or distribution of this Manual 
is permitted.  This Manual may not be sold and may not be 
distributed to or used by any student or other third party.  No part 
of this Manual may be reproduced, displayed or distributed in any 
form or by any means, electronic or otherwise, without the prior 
written permission of McGraw-Hill.   
 
 
PROPRIETARY MATERIAL.  © The McGraw-Hill Companies, Inc.  All rights 
reserved.  No part of this Manual may be displayed, reproduced or distributed in any 
form or by any means, without the prior written permission of the publisher, or used 
beyond the limited distribution to teachers and educators permitted by McGraw-Hill 
for their individual course preparation.  If you are a student using this Manual, you 
are using it without permission. 
Solution Manual, Chapter 14 – Turbomachinery 
 
 
 
 
Chapter 14 
Turbomachinery 
 
General Problems 
 
14-1C 
Solution We are to discuss energy producing and energy absorbing devices.  
 
Analysis A more common term for an energy producing turbomachine is a 
turbine. Turbines extract energy from the moving fluid, and convert that energy into 
useful mechanical energy in the surroundings, usually in the form of a rotating shaft. 
Thus, the phrase “energy producing” is from a frame of reference of the fluid – the 
fluid loses energy as it drives the turbine, producing energy to the surroundings. On 
the other hand, a more common term for an energy absorbing turbomachine is a 
pump. Pumps absorb mechanical energy from the surroundings, usually in the form 
of a rotating shaft, and increase the energy of the moving fluid. Thus, the phrase 
“energy absorbing” is from a frame of reference of the fluid – the fluid gains or 
absorbs energy as it flows through the pump. 
 
Discussion From the frame of reference of the surroundings, a pump absorbs 
energy from the surroundings, while a turbine produces energy to the surroundings. 
Thus, you may argue that the terminology also holds for the frame of reference of the 
surroundings. This alternative explanation is also acceptable. 
 
 
 
 
14-2C 
Solution We are to discuss the differences between fans, blowers, and 
compressors. 
 
Analysis A fan is a gas pump with relatively low pressure rise and high flow 
rate. A blower is a gas pump with relatively moderate to high pressure rise and 
moderate to high flow rate. A compressor is a gas pump designed to deliver a very 
high pressure rise, typically at low to moderate flow rates. 
 
Discussion The boundaries between these three types of pump are not always 
clearly defined. 
 
 
 
 
14-1 
 
PROPRIETARY MATERIAL.  © The McGraw-Hill Companies, Inc.  All rights 
reserved.  No part of this Manual may be displayed, reproduced or distributed in any 
form or by any means, without the prior written permission of the publisher, or used 
beyond the limited distribution to teachers and educators permitted by McGraw-Hill 
for their individual course preparation.  If you are a student using this Manual, you 
are using it without permission. 
Page 3


 
 
 
 
 
 
 
 
 
 
 
 
 
PROPRIETARY AND CONFIDENTIAL 
 
This Manual is the proprietary property of The McGraw-Hill 
Companies, Inc. (“McGraw-Hill”) and protected by copyright and other 
state and federal laws.  By opening and using this Manual the user 
agrees to the following restrictions, and if the recipient does not agree 
to these restrictions, the Manual should be promptly returned unopened 
to McGraw-Hill:  This Manual is being provided only to authorized 
professors and instructors for use in preparing for the classes using 
the affiliated textbook.  No other use or distribution of this Manual 
is permitted.  This Manual may not be sold and may not be 
distributed to or used by any student or other third party.  No part 
of this Manual may be reproduced, displayed or distributed in any 
form or by any means, electronic or otherwise, without the prior 
written permission of McGraw-Hill.   
 
 
PROPRIETARY MATERIAL.  © The McGraw-Hill Companies, Inc.  All rights 
reserved.  No part of this Manual may be displayed, reproduced or distributed in any 
form or by any means, without the prior written permission of the publisher, or used 
beyond the limited distribution to teachers and educators permitted by McGraw-Hill 
for their individual course preparation.  If you are a student using this Manual, you 
are using it without permission. 
Solution Manual, Chapter 14 – Turbomachinery 
 
 
 
 
Chapter 14 
Turbomachinery 
 
General Problems 
 
14-1C 
Solution We are to discuss energy producing and energy absorbing devices.  
 
Analysis A more common term for an energy producing turbomachine is a 
turbine. Turbines extract energy from the moving fluid, and convert that energy into 
useful mechanical energy in the surroundings, usually in the form of a rotating shaft. 
Thus, the phrase “energy producing” is from a frame of reference of the fluid – the 
fluid loses energy as it drives the turbine, producing energy to the surroundings. On 
the other hand, a more common term for an energy absorbing turbomachine is a 
pump. Pumps absorb mechanical energy from the surroundings, usually in the form 
of a rotating shaft, and increase the energy of the moving fluid. Thus, the phrase 
“energy absorbing” is from a frame of reference of the fluid – the fluid gains or 
absorbs energy as it flows through the pump. 
 
Discussion From the frame of reference of the surroundings, a pump absorbs 
energy from the surroundings, while a turbine produces energy to the surroundings. 
Thus, you may argue that the terminology also holds for the frame of reference of the 
surroundings. This alternative explanation is also acceptable. 
 
 
 
 
14-2C 
Solution We are to discuss the differences between fans, blowers, and 
compressors. 
 
Analysis A fan is a gas pump with relatively low pressure rise and high flow 
rate. A blower is a gas pump with relatively moderate to high pressure rise and 
moderate to high flow rate. A compressor is a gas pump designed to deliver a very 
high pressure rise, typically at low to moderate flow rates. 
 
Discussion The boundaries between these three types of pump are not always 
clearly defined. 
 
 
 
 
14-1 
 
PROPRIETARY MATERIAL.  © The McGraw-Hill Companies, Inc.  All rights 
reserved.  No part of this Manual may be displayed, reproduced or distributed in any 
form or by any means, without the prior written permission of the publisher, or used 
beyond the limited distribution to teachers and educators permitted by McGraw-Hill 
for their individual course preparation.  If you are a student using this Manual, you 
are using it without permission. 
Solution Manual, Chapter 14 – Turbomachinery 
 
14-3C 
Solution We are to list examples of fans, blowers, and compressors. 
 
Analysis Common examples of fans are window fans, ceiling fans, fans in 
computers and other electronics equipment, radiator fans in cars, etc. Common 
examples of blowers are leaf blowers, hair dryers, air blowers in furnaces and 
automobile ventilation systems. Common examples of compressors are tire pumps, 
refrigerator and air conditioner compressors. 
 
Discussion Students should come up with a diverse variety of examples. 
 
 
 
 
14-4C 
Solution We are to discuss the difference between a positive-displacement 
turbomachine and a dynamic turbomachine. 
 
Analysis A positive-displacement turbomachine is a device that contains a 
closed volume; energy is transferred to the fluid (pump) or from the fluid 
(turbine) via movement of the boundaries of the closed volume. On the other 
hand, a dynamic turbomachine has no closed volume; instead, energy is 
transferred to the fluid (pump) or from the fluid (turbine) via rotating blades. 
Examples of positive-displacement pumps include well pumps, hearts, some 
aquarium pumps, and pumps designed to release precise volumes of medicine. 
Examples of positive-displacement turbines include water meters and gas meters in 
the home. Examples of dynamic pumps include fans, centrifugal blowers, airplane 
propellers, centrifugal water pumps (like in a car engine), etc. Examples of 
dynamic turbines include windmills, wind turbines, turbine flow meters, etc. 
 
Discussion Students should come up with a diverse variety of examples. 
 
 
 
 
14-5C 
Solution We are to discuss the difference between brake horsepower and water 
horsepower, and then discuss pump efficiency. 
 
Analysis In turbomachinery terminology, brake horsepower is the power 
actually delivered to the pump through the shaft. (One may also call it “shaft 
power”.) On the other hand, water horsepower is the useful portion of the brake 
horsepower that is actually delivered to the fluid. Water horsepower is always less 
than brake horsepower; hence pump efficiency is defined as the ratio of water 
horsepower to brake horsepower. 
 
Discussion For a turbine, efficiency is defined in the opposite way, since brake 
horsepower is less than water horsepower. 
 
 
 
 
14-2 
 
PROPRIETARY MATERIAL.  © The McGraw-Hill Companies, Inc.  All rights 
reserved.  No part of this Manual may be displayed, reproduced or distributed in any 
form or by any means, without the prior written permission of the publisher, or used 
beyond the limited distribution to teachers and educators permitted by McGraw-Hill 
for their individual course preparation.  If you are a student using this Manual, you 
are using it without permission. 
Page 4


 
 
 
 
 
 
 
 
 
 
 
 
 
PROPRIETARY AND CONFIDENTIAL 
 
This Manual is the proprietary property of The McGraw-Hill 
Companies, Inc. (“McGraw-Hill”) and protected by copyright and other 
state and federal laws.  By opening and using this Manual the user 
agrees to the following restrictions, and if the recipient does not agree 
to these restrictions, the Manual should be promptly returned unopened 
to McGraw-Hill:  This Manual is being provided only to authorized 
professors and instructors for use in preparing for the classes using 
the affiliated textbook.  No other use or distribution of this Manual 
is permitted.  This Manual may not be sold and may not be 
distributed to or used by any student or other third party.  No part 
of this Manual may be reproduced, displayed or distributed in any 
form or by any means, electronic or otherwise, without the prior 
written permission of McGraw-Hill.   
 
 
PROPRIETARY MATERIAL.  © The McGraw-Hill Companies, Inc.  All rights 
reserved.  No part of this Manual may be displayed, reproduced or distributed in any 
form or by any means, without the prior written permission of the publisher, or used 
beyond the limited distribution to teachers and educators permitted by McGraw-Hill 
for their individual course preparation.  If you are a student using this Manual, you 
are using it without permission. 
Solution Manual, Chapter 14 – Turbomachinery 
 
 
 
 
Chapter 14 
Turbomachinery 
 
General Problems 
 
14-1C 
Solution We are to discuss energy producing and energy absorbing devices.  
 
Analysis A more common term for an energy producing turbomachine is a 
turbine. Turbines extract energy from the moving fluid, and convert that energy into 
useful mechanical energy in the surroundings, usually in the form of a rotating shaft. 
Thus, the phrase “energy producing” is from a frame of reference of the fluid – the 
fluid loses energy as it drives the turbine, producing energy to the surroundings. On 
the other hand, a more common term for an energy absorbing turbomachine is a 
pump. Pumps absorb mechanical energy from the surroundings, usually in the form 
of a rotating shaft, and increase the energy of the moving fluid. Thus, the phrase 
“energy absorbing” is from a frame of reference of the fluid – the fluid gains or 
absorbs energy as it flows through the pump. 
 
Discussion From the frame of reference of the surroundings, a pump absorbs 
energy from the surroundings, while a turbine produces energy to the surroundings. 
Thus, you may argue that the terminology also holds for the frame of reference of the 
surroundings. This alternative explanation is also acceptable. 
 
 
 
 
14-2C 
Solution We are to discuss the differences between fans, blowers, and 
compressors. 
 
Analysis A fan is a gas pump with relatively low pressure rise and high flow 
rate. A blower is a gas pump with relatively moderate to high pressure rise and 
moderate to high flow rate. A compressor is a gas pump designed to deliver a very 
high pressure rise, typically at low to moderate flow rates. 
 
Discussion The boundaries between these three types of pump are not always 
clearly defined. 
 
 
 
 
14-1 
 
PROPRIETARY MATERIAL.  © The McGraw-Hill Companies, Inc.  All rights 
reserved.  No part of this Manual may be displayed, reproduced or distributed in any 
form or by any means, without the prior written permission of the publisher, or used 
beyond the limited distribution to teachers and educators permitted by McGraw-Hill 
for their individual course preparation.  If you are a student using this Manual, you 
are using it without permission. 
Solution Manual, Chapter 14 – Turbomachinery 
 
14-3C 
Solution We are to list examples of fans, blowers, and compressors. 
 
Analysis Common examples of fans are window fans, ceiling fans, fans in 
computers and other electronics equipment, radiator fans in cars, etc. Common 
examples of blowers are leaf blowers, hair dryers, air blowers in furnaces and 
automobile ventilation systems. Common examples of compressors are tire pumps, 
refrigerator and air conditioner compressors. 
 
Discussion Students should come up with a diverse variety of examples. 
 
 
 
 
14-4C 
Solution We are to discuss the difference between a positive-displacement 
turbomachine and a dynamic turbomachine. 
 
Analysis A positive-displacement turbomachine is a device that contains a 
closed volume; energy is transferred to the fluid (pump) or from the fluid 
(turbine) via movement of the boundaries of the closed volume. On the other 
hand, a dynamic turbomachine has no closed volume; instead, energy is 
transferred to the fluid (pump) or from the fluid (turbine) via rotating blades. 
Examples of positive-displacement pumps include well pumps, hearts, some 
aquarium pumps, and pumps designed to release precise volumes of medicine. 
Examples of positive-displacement turbines include water meters and gas meters in 
the home. Examples of dynamic pumps include fans, centrifugal blowers, airplane 
propellers, centrifugal water pumps (like in a car engine), etc. Examples of 
dynamic turbines include windmills, wind turbines, turbine flow meters, etc. 
 
Discussion Students should come up with a diverse variety of examples. 
 
 
 
 
14-5C 
Solution We are to discuss the difference between brake horsepower and water 
horsepower, and then discuss pump efficiency. 
 
Analysis In turbomachinery terminology, brake horsepower is the power 
actually delivered to the pump through the shaft. (One may also call it “shaft 
power”.) On the other hand, water horsepower is the useful portion of the brake 
horsepower that is actually delivered to the fluid. Water horsepower is always less 
than brake horsepower; hence pump efficiency is defined as the ratio of water 
horsepower to brake horsepower. 
 
Discussion For a turbine, efficiency is defined in the opposite way, since brake 
horsepower is less than water horsepower. 
 
 
 
 
14-2 
 
PROPRIETARY MATERIAL.  © The McGraw-Hill Companies, Inc.  All rights 
reserved.  No part of this Manual may be displayed, reproduced or distributed in any 
form or by any means, without the prior written permission of the publisher, or used 
beyond the limited distribution to teachers and educators permitted by McGraw-Hill 
for their individual course preparation.  If you are a student using this Manual, you 
are using it without permission. 
Solution Manual, Chapter 14 – Turbomachinery 
 
14-6C 
Solution We are to discuss the difference between brake horsepower and water 
horsepower, and then discuss turbine efficiency. 
 
Analysis In turbomachinery terminology, brake horsepower is the power 
actually delivered by the turbine to the shaft. (One may also call it “shaft power”.) 
On the other hand, water horsepower is the power extracted from the water 
flowing through the turbine. Water horsepower is always greater than brake 
horsepower; because of inefficiencies; hence turbine efficiency is defined as the 
ratio of brake horsepower to water horsepower. 
 
Discussion For a pump, efficiency is defined in the opposite way, since brake 
horsepower is greater than water horsepower. 
 
 
 
 
14-7C 
Solution We are to explain the “extra” term in the Bernoulli equation in a 
rotating reference frame. 
 
Analysis A rotating reference frame is not an inertial reference frame. When we 
move outward in the radial direction, the absolute velocity at this location is faster 
due to the rotating body, since v
?
 is equal to ?r. When solving a turbomachinery 
problem in a rotating reference frame, we use the relative fluid velocity (velocity 
relative to the rotating reference frame). Thus, in order for the Bernoulli equation 
to be physically correct, we must subtract the absolute velocity of the rotating 
body so that the equation applies to an inertial reference frame. This accounts 
for the “extra” term. 
 
Discussion The Bernoulli equation is the same physical equation in either the 
absolute or the rotating reference frame, but it is more convenient to use the form with 
the extra term in turbomachinery applications. 
 
 
 
 
14-3 
 
PROPRIETARY MATERIAL.  © The McGraw-Hill Companies, Inc.  All rights 
reserved.  No part of this Manual may be displayed, reproduced or distributed in any 
form or by any means, without the prior written permission of the publisher, or used 
beyond the limited distribution to teachers and educators permitted by McGraw-Hill 
for their individual course preparation.  If you are a student using this Manual, you 
are using it without permission.