1The thermal efficiency of a gas turbine engine depends on the _________gas temperature at turbine inlet
a. allowable maximum
b. allowable minimum
c. considerable amount
d. minimum
a. allowable maximum
2The two major application areas of gas turbine engines are
a. driving automotive engine and locomotives
b. heating and generation
c. aircraft propulsion and electric power generation
d. none of these
c. aircraft propulsion and electric power generation
3When it is used for aircraft propulsion
the gas turbine produces just enough power to drive the compressor and a small generator to power the
a. pump
b. generator
c. auxilliary equipments
d. controlled devices
4The ________ are also used for stationary power plants to generate electricity
a. Carnot engine
b. Stirling engine
c. Gas turbine engine
d. steam engine
c. Gas turbine engine
5Are mostly utilized in the power generation industry to cover emergencies and peak periods because of their relative low cost and quick response time
a. Geothermal power plants
b. Diesel power plants
c. Gas turbine power plants
d. Thermal power plants
c. Gas turbine power plants
6Compared to steam turbine engines and diesel propulsion systems
the gas turbine offers _____for a given size and weight
7The engine start up time has been reduced from 4 hours required for a typical steam propulsion system to _______for a gas turbine
a. less than 2 min
b. less than 30 min
c. more than 1 hr
d. less than 5 minutes
a. less than 2 min
8Many modern marine propulsion systems used gas turbines together with
a. Diesel engine
b. Gasoline engine
c. Stirling engine
d. Carnot engine
a. Diesel engine
9Is the ratio of compressor work to the turbine work in gas turbine power plants
a. Back work ratio
b. Thermal efficiency
c. Heat ratio
d. Combined ratio
a. Back work ratio
10In gas turbine usually more than one-half of the turbine work output is used to drive the
a. engine
b. generator
c. compressor
d. auxilliaries
c. compressor
11The turbines used in gas turbine power plant are _______than those used in steam power plants of the same power rating
a. smaller
b. considerable power
c. powerful
d. large
d. large
12In gas turbine engines
the temperature of the exhaust gas leaving the turbine is often considerable _____than the temperature of the air leaving the compressor
a. lower
b. higher
c. controllable
d. none of these
13The high pressure air leaving the compressor can be heated by transferring heat to it from the hot exhaust gases in a counter flow heat exchanger known as
a. regenerator machine
b. boiler
c. adiabatic
d. recuperator
d. recuperator
14The thermal efficiency of the Brayton cycle increases as a result of
a. isentropic compression
b. isentropic expansion
c. superposing
d. regeneration
d. regeneration
15The use of regenerator in is recommended only when the turbine exhaust temperature is higher than the compressor
a. exit temperature
b. inlet temperature
c. mean temperature
d. absolute temperature
a. exit temperature
16The highest temperature occuring within the regenerator is the temperature of exhaust gases leaving the turbine and
a. leaving the regenerator
b. entering the regenerator
c. leaving the turbine
d. entering the compressor
b. entering the regenerator
17Effectiveness of regenerator is the ratio of actual heat regenerated and the
a. minimum regenerated heat
b. maximum regenerated heat
c. maximum regenerated work
d. maximum regenerated energy
b. maximum regenerated heat
18The higher the effectiveness of regenerator
will save a greater amount of
a. work
b. heat
c. energy
d. fuel
19The thermal efficiency of an ideal Brayton cycle with regeneration depends on the ratio of the minimum to maximum temperature as well as the
a. entropy ratio
b. back work ratio
c. power ratio
d. pressure ratio
d. pressure ratio
20Is most effective at lower pressure ratios and low minimum-to-maximum temperature ratios
a. boiler
b. heat generation
c. regeneration
d. recuperation
c. regeneration
21The net work of Gas turbine cycle can be increased by decreasing the compresssor work or by
a. increasing the turbine work
b. decreasing turbine work
c. recuperation
d. expansion
a. increasing the turbine work
22As the number of stages increased in multi compression with intercooling
the compression process becomes isothermal at the compressor inlet temperature
23The work ouput of a turbine operating between two pressure levels can be increased_______and reheating it in between-that is
utilizing multi expansion with reheating
a. compressing the gas in stages
b. utilizing the gas in stages
c. reheating the gas in stages
d. expanding the gas in stages
24As the number of stages is increased
the expansion process becomes
a. isentropic
b. isothermal
c. isometric
d. polytropic
25The steady flow compression or expansion work is proportional to the
a. density of fluid
b. specific gravity of liquid
c. specific weight of liquid
d. specific volume of liquid
d. specific volume of liquid
26The back work ratio of a gas turbine cycle improves as a result of
a. intercooling and reheating
b. reheating
c. cooling
d. superposing
a. intercooling and reheating
27Intercooling and reheating will always____the thermal efficiency unless they are accompanied by regeneration
a. decrease
b. increase
c. remains constant
d. none of these
a. decrease
28Intercooling decreases the average temperature at which heat is added
and reheating increases the average temperature at which heat is
a. limited
b. added
c. rejected
d. none of these
29Gas turbine engines are widely used to power aircraft because they are light and compact and
a. high power to weight ratio
b. low power to weigh ratio
c. high power to volume ratio
d. low work ratio
a. high power to weight ratio
30Aircraft gas turbines operate on an open cycle called
a. automatic cycle
b. jet propulsion cycle
c. Carnot cycle
d. Reheat cycle
b. jet propulsion cycle
31The net work output of a jet-propulsion cycle is
a. zero
b. infinity
c. one percent
d. maximum
a. zero
32Aircraft gas turbines operate at higher pressure ratio typically between
a. 6 to 8
b. 12 to 24
c. 10 to 18
d. 10 to 25
d. 10 to 25
33A SIMPLE ideal brayton cycle WITHOUT REGENERATION is modified to incorporate MULTISTAGE COMPRESSION with INTERCOOLING and MULTI STAGE EXPANSION with reheating
without changing the pressure or temperature limits of the cycle. As the result of modification
34Aircraft are propelled by accelerating a fluid in the opposite direction to
a. acceleration
b. direction
c. motion
d. none of these
c. motion
35The gases expand in a nozzle to the ambient pressure and leave the aircraft at a
a. low heat
b. low work
c. low cost
d. high velocity
d. high velocity
36The thrust developed in a turbojet engine is the unbalance force which is caused by the difference in the _________ of the low velocity air entering the engine and the high velocity exhaust gases leaving the engine
a. momentum
b. power
c. impulsive power
d. impact energy
a. momentum
37The power developed from the thrust of the engine is called the
a. impulsive power
b. supersonic power
c. propulsive power
d. transitive power
c. propulsive power
38The net work developed by a turbojet engine
a. infinity
b. one
c. zero
d. none of these
c. zero
39Is the ratio of propulsive power and energy input rate
a. thermal efficiency
b. adiabatic efficiency
c. Turbojet efficiency
d. Propulsive efficiency
d. Propulsive efficiency
40The most widely used engine in aircraft propulsion is the
a. supercharge fan engine
b. turbofan engine
c. stirring fan engine
d. colative fan engine
b. turbofan engine
41The ratio of the mass flow rate of air bypassing the combustion chamber to that of air flowing through it is called
a. efficiency ratio
b. bypass ratio
c. compression ratio
d. heat transfer ratio
b. bypass ratio
42The first commercial high-pass ratio engines has a bypass ratio of
a. 1
b. 3
c. 5
d. 7
c. 5
43increasing the bypass ratio of a turbofan engine
a. increase thrust
b. increase power
c. increase heat
d. increase energy
a. increase thrust
44As a general rule
propellers are more efficient than
a. Carnot engines
b. Dual engines
c. Ericsson engines
d. Jet engines
45Another modification which is popular with military aircraft is the addition of an
a. anti-burner
b. afterburner
c. cooler burnee
d. header
b. afterburner
46is a properly shaped duct with no compressor or turbine
a. Turbojet engine
b. Supercharged engine
c. Adiabatic engine
d. Ramjet engine
d. Ramjet engine
47Ramjet is used for high-speed propulsion of
a. aircraft carrier
b. missiles and aircraft
c. supercharging
d. exposing
b. missiles and aircraft
48A______is essentially a ramjet in which air flows through at supersonic speeds.
a. turbojet enginea
b. Crumjet engine
c. Chargeable engine
d. Scramjet engine
d. Scramjet engine
49A cycle which a net amount of work is produced is called
a. ideal cycle
b. actual cycle
c. power cycle
d. steam cycle
c. power cycle
50A power cycle during which the working fluid remains a gas throughout is called a ______cycle
a. heat power
b. fuel power
c. true power
d. gas power
d. gas power
51The single-stage compression process of an ideal Brayton cycle without regeneration is replaced by a multistage COMPRESSION process with intercooling between the same pressure limits. As a result of modification
the compressor work:
a. increase
b. decrease
c. remain constant
d. none of these
52The single-stage compression process of an ideal Brayton cycle without regeneration is replaced by a multistage COMPRESSION process with intercooling between the same pressure limits. As a result of modification
the backwork ratio:
a. increase
b. decrease
c. remain constant
d. none of these
53The single-stage expansion process of an ideal Brayton cycle without regeneration is replaced by a multistage EXPANSION process with REHEATING between the same pressure limits. As a result of modification
the turbine work will:
a. increase
b. decrease
c. remain constant
d. none of these
54The single-stage expansion process of an ideal Brayton cycle without regeneration is replaced by a multistage EXPANSION process with REHEATING between the same pressure limits. As a result of modification
back work ratio will:
a. increase
b. decrease
c. remain constant
d. none of these
55The single-stage expansion process of an ideal Brayton cycle without regeneration is replaced by a multistage EXPANSION process with REHEATING between the same pressure limits. As a result of modification
thermal efficiency will:
a. increase
b. decrease
c. remain constant
d. none of these
56The single-stage compression process of an ideal Brayton cycle without regeneration is replaced by a multistage COMPRESSION process with intercooling between the same pressure limits. As a result of modification
the thermal efficiency:
a. increase
b. decrease
c. remain constant
d. none of these
57A SIMPLE ideal brayton cycle WITHOUT REGENERATION is modified to incorporate MULTISTAGE COMPRESSION with INTERCOOLING and MULTI STAGE EXPANSION with reheating
without changing the pressure or temperature limits of the cycle. As the result of modification
58A SIMPLE ideal brayton cycle WITHOUT REGENERATION is modified to incorporate MULTISTAGE COMPRESSION with INTERCOOLING and MULTI STAGE EXPANSION with reheating
without changing the pressure or temperature limits of the cycle. As the result of modification
59A SIMPLE ideal brayton cycle WITHOUT REGENERATION is modified to incorporate MULTISTAGE COMPRESSION with INTERCOOLING and MULTI STAGE EXPANSION with reheating
without changing the pressure or temperature limits of the cycle. As the result of modification
60A SIMPLE ideal brayton cycle WITHOUT REGENERATION is modified to incorporate MULTISTAGE COMPRESSION with INTERCOOLING and MULTI STAGE EXPANSION with reheating
without changing the pressure or temperature limits of the cycle. As the result of modification
61A SIMPLE ideal Brayton cycle is modified to incorporate multistage compression with intercooling
multistage expansion with reheating and regeneration without changing the pressure limits of the cycle. As a result of modification
62A SIMPLE ideal Brayton cycle is modified to incorporate multistage compression with intercooling
multistage expansion with reheating and regeneration without changing the pressure limits of the cycle. As a result of modification
63A SIMPLE ideal Brayton cycle is modified to incorporate multistage compression with intercooling
multistage expansion with reheating and regeneration without changing the pressure limits of the cycle. As a result of modification
64A SIMPLE ideal Brayton cycle is modified to incorporate multistage compression with intercooling
multistage expansion with reheating and regeneration without changing the pressure limits of the cycle. As a result of modification
65Which of the following is not considered as heat engines?
a. Stirling cycle
b. Ericsson cycle
c. Brayton cycle
d. All of these
d. All of these
66Which of the following is/are the application of Brayton cycle
a. Propulsion system
b. Automotive turbine engines
c. Aircraft Turbine Engines
d. all of these
d. all of these
67Which of the following is considered as internal combustion engine
a. Brayton cycle
b. Atkinson cycle
c. Humpherey pump
d. all of these
d. all of these
68The property that describes the randomness or uncertainty is called
a. temperature
b. entropy
c. pressure
d. internal energy
b. entropy
69Air by volume:
a. 11% Oxygen & 89% Nitrogen
b. 20% Oxygen & 80% Nitrogen
c. 121% Oxygen & 79% Nitrogen
d. 40% Oxygen & 60% Nitrogen
c. 121% Oxygen & 79% Nitrogen
70Is defined as the actual fuel air ratio over the stoichiometric fuel air ratio.
a. Back work ratio
b. Volumetric ratio
c. air-fuel ratio
d. equivalent ratio
d. equivalent ratio
71In a polytropic process
if n=0
72In a polytropic process
if _________
73In a polytropic process
if n=infinity
74In a polytropic process
if ______
75Power generation coupled with process heating is called
a. generation
b. combination
c. cogeneration
d. regeneration
c. cogeneration
76Steam is the most common working fluid used in vapor cycles because of its many desirable characteristics
such as
a. low cost
b. availability
c. high enthalpy vaporization
d. all of these
77It is used as working fluid in high-temperature applications of vapor cycles
a. Helium
b. Deuterium
c. mercury
d. water
c. mercury
78Are commonly referred to as coal plants
nuclear plants
79In Carnot cycle
a. Water is heated reversibly and isothermally in a boiler
b. Expanded isentropically in the turbine
c. Condensed reversibly and isothermally in a condenser
d. all of these
d. all of these
80The critical point value is ________for water
a. 234⁰C
b. 374⁰C
c. 498⁰C
d. 563⁰C
b. 374⁰C
81Limiting the maximum temperature in the Carnot cycle also limits the
a. compression ratio
b. pressure ratio
c. thermal efficiency
d. none of these
c. thermal efficiency
82Is the ideal cycle for vapor power plants
a. Carnot cycle
b. Stirling cycle
c. Rankine cycle
d. Combined cycle
c. Rankine cycle
83In a Rankine cycle
water enters
the pump as saturated liquid and is compressed isentropically to the operating pressure of the
a. heat exchanger
b. recuperator
c. condenser
d. boiler
84In the pump
the water temperature increases somewhat during this isentropic compression process due to
a. a slight decrease in pressure of water
b. a slight decrease in specific volume of water
c. a slight increase in specific volumebof air
d. a slight decrease in specific volume of fluid
85The superheated vapor enters the turbine and expands isentropically and produces work by the rotating shaft. The _______may drop during the process
a. density
b. viscocity of fuel
c. temperature and pressure
d. none of these
c. temperature and pressure
86Steam is condensed at constant pressure in the
a. condenser
b. boiler
c. turbine
d. pump
a. condenser
87If the power plant is cooled by air instead of water
this method is called
a. wet cooling
b. dry cooling
c. specific cooling
d. air cooled cooling
88The area under T-S diagram represents the
a. work
b. heat transfer
c. energy
d. none of these
b. heat transfer
89The boiler and condenser do not involve any work
and the pump and turbine are assumed to be
a. isentropic
b. isothermal
c. adiabatic
d. none of these
90The conversion efficiency of power plants in the United States is often expressed in terms of _______which is the amount of heat supplied
in Btu's to generate 1Kwh of electricity
a. fuel rate
b. work-heat ratio
c. contact ratio
d. heat rate
91The smaller the heat rate
the greater the
a. effectiveness
b. efficiency
c. heat
d. fuel
921 kwh =
a. 3412 Btu
b. 200 Btu
c. 5012 Btu
d. 1089Btu
a. 3412 Btu
93Rankine cycle power plant converts ______of the heat it receives in the boiler to net work
a. 24%
b. 26%
c. 28%
d. 30%
b. 26%
94The back work ratio of this power plant is
a. 0.001
b. 0.002
c. 0.003
d. 0.004
d. 0.004
95Only_____of the turbine work output is required to operate the pump
a. 0.01%
b. 0.02%
c. 0.03%
d. 0.04%
d. 0.04%
96Causes pressure drops in the boiler
the condenser
97The pressure in the condenser is usually
a. very large
b. positive
c. negative
d. very small
d. very small
98To compensate pressure drops in Rankine cycle
the water must be pumped to a sufficient ______than the ideal cycle
a. higher pressure
b. lower pressure
c. higher temperature
d. lower temperature
99The major source of irreversibility is the _______from the steam to the surroundings
a. work input
b. work output
c. heat loss
d. heat added
c. heat loss
100To increase the thermal efficiency of Rankine cycle
______at which heat is transferred to the working fluid in the boiler.
a. decrease pressure
b. increase the average temperature
c. increase temperature only
d. none of these