Turbine Engine Compressors

Question 1 of 32

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What is the configuration/description of a centrifugal compressor?

Select one or more of the following:

  • Short in length, spoke-like design, easy to manufacture, with high compression per stage.

  • Long in length, spoke-like design, easy to manufacture, with moderate compression per stage.

  • Long in length, spoke-like design, easy to manufacture, with high compression per stage.

  • Short in length, spoke-like design, easy to manufacture, with moderate compression per stage.

Question 2 of 32

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What are the advantages of a centrifugal compressor over an axial flow compressor?

Select one or more of the following:

  • Cheaper and easier to manufacture, more robust, better handling of FOD ingestion, less prone to stalling and surging, relatively lower in weight.

  • Cheaper and easier to manufacture, more robust, better handling of FOD ingestion, less prone to stalling and surging, relatively higher in weight.

  • Cheaper and easier to manufacture, more robust, better handling of FOD ingestion, more prone to stalling and surging, relatively lower in weight.

  • Cheaper and harder to manufacture, more robust, better handling of FOD ingestion, less prone to stalling and surging, relatively lower in weight.

Question 3 of 32

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What is an impellor?

Select one or more of the following:

  • The internal rotating component of a centrifugal compressor, which takes inlet/intake air at its centre and compresses it by centrifugal force. Sometimes known as the rotor.

  • The internal rotating component of a axial compressor, which takes inlet/intake air at its centre and compresses it by centrifugal force. Sometimes known as the rotor.

  • The internal rotating component of a axial compressor, which takes inlet/intake air and compresses it by centrifugal force. Sometimes known as the rotor.

  • The internal rotating component of a centrifugal compressor, which takes inlet/intake air and compresses it by centrifugal force. Sometimes known as the rotor.

Question 4 of 32

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What is the purpose of the diffuser?

Select one or more of the following:

  • To decrease the airs velocity and increase its pressure

  • To decrease the airs velocity and decrease its pressure

  • To increase the airs velocity and increase its pressure

  • To increase the airs velocity and decrease its pressure

Question 5 of 32

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Where does the air pressure increase as it passes through centrifugal compressor?

Select one or more of the following:

  • Air pressure increases progressively through the impeller and increases rapidly through the diffuser

  • Air pressure decreases progressively through the impeller and increases rapidly through the diffuser

  • Air pressure increases rapidly through the impeller and increases progressively through the diffuser

  • Air pressure increases rapidly through the impeller and increases rapidly through the diffuser

Question 6 of 32

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How does the velocity and pressure vary through a centrifugal compressor?

Select one or more of the following:

  • Velocity and pressure both increase through the impeller, however through the diffuser the velocity decreases and pressure increases

  • Velocity and pressure both decrease through the impeller, however through the diffuser the velocity decreases and pressure increases

  • Velocity and pressure both decrease through the impeller, however through the diffuser the velocity increases and pressure increases

  • Velocity and pressure both increase through the impeller, however through the diffuser the velocity increases and pressure increases

Question 7 of 32

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What is the configuration/description of an axial flow compressor?

Select one or more of the following:

  • Multiple stages of rotating aerofoil blades and fixed vanes (stators), with a large mass flow capacity and high efficiency.

  • Multiple stages of rotating aerofoil blades and fixed vanes (stators), with a large mass flow capacity and high thrust

  • Multiple stages of rotating aerofoil blades and moving vanes (stators), with a large mass flow capacity and high thrust

  • Multiple stages of rotating aerofoil blades and moving vanes (stators), with a large mass flow capacity and high efficiency.

Question 8 of 32

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What are the advantages of an axial flow compressor over a centrifugal compressor of the same frontal diameter?

Select one or more of the following:

  • Higher compressor pressure ratios and greater mass airflow

  • Higher compressor airflow ratios and greater mass airflow

  • Higher compressor speeds and greater mass airflow

  • Higher compressor speeds and greater fuel capacity

Question 9 of 32

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What are the advantages of an axial flow compressor over a centrifugal compressor?

Select one or more of the following:

  • A lower frontal area for a given mass airflow, which allows for a smaller diameter engine, achieves higher compression ratios more efficiently, lower pressure rise per stage, a much lower airflow exit velocity compared to its inlet velocity

  • A higher frontal area for a given mass airflow, which allows for a smaller diameter engine, achieves higher compression ratios more efficiently, lower pressure rise per stage, a much lower airflow exit velocity compared to its inlet velocity

  • A higher frontal area for a given mass airflow, which allows for a smaller diameter engine, achieves higher compression ratios more efficiently, higher pressure rise per stage, a much lower airflow exit velocity compared to its inlet velocity

  • A lower frontal area for a given mass airflow, which allows for a smaller diameter engine, achieves higher compression ratios more efficiently, higher pressure rise per stage, a much lower airflow exit velocity compared to its inlet velocity

Question 10 of 32

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What is the definition of the compressor pressure ratio?

Select one or more of the following:

  • The ratio of the compressor outlet pressure to the compressor inlet pressure

  • The ratio of the compressor outlet pressure to the compressor inlet temperature

  • The ratio of the compressor outlet velocity to the compressor inlet velocity

  • The ratio of the compressor outlet velocity to the compressor inlet temperature

Question 11 of 32

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What is the typical total compressor ratio of a single stage centrifugal compressor?

Select one or more of the following:

  • Up to about 7.5:1

  • Up to about 15:1

  • Up to about 20:1

  • Up to about 30:1

Question 12 of 32

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What is the typical total compressor ratio of a double stage centrifugal compressor?

Select one or more of the following:

  • Up to about 15:1

  • Up to about 7.5:1

  • Up to about 20:1

  • Up to about 3:1

Question 13 of 32

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What is the typical total pressure ratio of a modern axial flow compressor?

Select one or more of the following:

  • 20:1, but up to 30:1 in come cases

  • 10:1, but up to 20:1 in come cases

  • 10:1, but up to 30:1 in come cases

  • 15:1, but up to 20:1 in come cases

Question 14 of 32

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How does the temperature, pressure and velocity of the air change as it passes through each stage of an axial flow compressor?

Select one or more of the following:

  • Temperature and pressure progressively increase and the axial velocity increases across the rotors and decreases across the stators, but overall velocity decreases considering the effect of the diffuser

  • Temperature and pressure progressively increase and the axial velocity decreases across the rotors and decreases across the stators, but overall velocity decreases considering the effect of the diffuser

  • Temperature and pressure progressively increase and the axial velocity decreases across the rotors and increases across the stators, but overall velocity decreases considering the effect of the diffuser

  • Temperature and pressure progressively increase and the axial velocity increases across the rotors and increases across the stators, but overall velocity decreases considering the effect of the diffuser

Question 15 of 32

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What is the function of inlet guide vanes?

Select one or more of the following:

  • The inlet guide vanes are designed to direct the airflow onto the first stage rotors at an appropriate angle of attack.

  • The inlet guide vanes are designed to direct the airflow onto the last stage rotors at an appropriate angle of attack.

  • The inlet guide vanes are designed to direct the airflow onto the last stage rotors at an high angle of attack.

  • The inlet guide vanes are designed to direct the airflow onto the first stage rotors at an high angle of attack.

Question 16 of 32

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What is the function of the variable inlet guide vanes?

Select one or more of the following:

  • To change angle depending on flow characteristics, directing the airflow onto the first stage rotors at the optimal angle of attack, thereby reducing the chance of a compressor stall during operation off design (at low) rpm.

  • To change angle depending on pressure characteristics, directing the airflow onto the first stage rotors at the optimal angle of attack, thereby reducing the chance of a compressor stall during operation off design (at low) rpm.

  • To change angle depending on pressure characteristics, directing the airflow onto the first stage rotors at the optimal angle of attack, thereby reducing the chance of a compressor stall during operation off design (at high) rpm.

  • To change angle depending on flow characteristics, directing the airflow onto the first stage rotors at the optimal angle of attack, thereby reducing the chance of a compressor stall during operation off design (at high) rpm.

Question 17 of 32

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What is the function of the variable stators in an axial flow compressor?

Select one or more of the following:

  • The variable stators are designed to direct the airflow onto the subsequent stage of rotors at the optimum angle of attack, thereby increasing the compressor pressure ratio.

  • The variable stators are designed to direct the airflow onto the first stage of rotors at the optimum angle of attack, thereby increasing the compressor pressure ratio.

  • The variable stators are designed to direct the airflow onto the first stage of rotors at the optimum angle of attack, thereby increasing the overall thrust

  • The variable stators are designed to direct the airflow onto the subsequent stage of rotors at the optimum angle of attack, thereby increasing the overall thrust

Question 18 of 32

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What is the primary function of each row of stator blades?

Select one or more of the following:

  • To convert the kinetic energy of the airflow into pressure energy

  • To convert the kinetic energy of the airflow into dynamic energy

  • To convert the dynamic energy of the airflow into kinetic energy

  • To convert the dynamic energy of the airflow into pressure energy

Question 19 of 32

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What is the secondary function of the stator blades?

Select one or more of the following:

  • To stop swirl in the air thereby maintaining axial flow as it passes through the compressor

  • To stop swirl in the air thereby maintaining centrifugal flow as it passes through the compressor

  • To allow swirl in the air thereby maintaining centrifugal flow as it passes through the compressor

  • To allow swirl in the air thereby maintaining axial flow as it passes through the compressor

Question 20 of 32

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What are the function of the rotors and stators in an axial flow compressor?

Select one or more of the following:

  • The rotors accelerate the airflow and the stators decelerate the flow to increase the airs pressure

  • The rotors decelerate the airflow and the stators decelerate the flow to increase the airs pressure

  • The rotors dedcelerate the airflow and the stators accelerate the flow to increase the airs pressure

  • The rotors accelerate the airflow and the stators accelerate the flow to increase the airs pressure

Question 21 of 32

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What shape does an axial flow compressor form towards the combustion chamber?

Select one or more of the following:

  • A converging duct

  • A diverging duct

  • A straight duct

Question 22 of 32

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Why does the air annulus area decrease towards the high pressure end of an axial flow compressor?

Select one or more of the following:

  • To allow for the reduction in the volume of air as its pressure progressively increases and to maintain the axial velocity of the air constant as the density increases

  • To allow for the increase in the volume of air as its pressure progressively increases and to maintain the axial velocity of the air constant as the density decreases

  • To allow for the increase in the volume of air as its pressure progressively increases and to maintain the axial velocity of the air constant as the density increases

  • To allow for the reduction in the volume of air as its pressure progressively increases and to maintain the axial velocity of the air constant as the density decreases

Question 23 of 32

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Why is there only a small pressure increase across each stage of an axial flow compressor?

Select one or more of the following:

  • Because the aerofoil blades are, by necessity, quite small and consequently only produce a small amount of lift at each stage

  • Because the aerofoil blades are, by necessity, quite large and consequently only produce a small amount of lift at each stage

  • Because the aerofoil blades are, by necessity, quite large and consequently only produce a small amount of thrust at each stage

  • Because the aerofoil blades are, by necessity, quite small and consequently only produce a small amount of thrust at each stage

Question 24 of 32

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What is a likely result from unstable airflow through a compressor?

Select one or more of the following:

  • A compressor stall.

  • A turbine stall.

  • An engine mafunction

  • A partial loss of power

Question 25 of 32

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What determines the angle of attack of a compressor blade at a given blade angle at any given time?

Select one or more of the following:

  • The RPM of the compressor an the TAS of the airflow

  • The angle of the airflow from the previous location

  • The smoothness of the air entering

  • The RPM of the turbine and the TAS of the airflow

Question 26 of 32

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What is the condition that leads to compressor stalls?

Select one or more of the following:

  • The axial velocity of the airflow is too low relative to the RPM.

  • The axial pressure of the airflow is too low relative to the RPM.

  • The axial temperature of the airflow is too low relative to the RPM.

  • The axial density of the airflow is too low relative to the RPM.

Question 27 of 32

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What is the principle effect/purpose of the bleed valves/bands in the compressor?

Select one or more of the following:

  • To offload the compressor (LP and HP) and increase the mass airflow through the early stages of the compressor, during acceleration from low engine speed thereby reducing the possibility of compressor stall and surge at low rpm.

  • To offload the compressor (LP and HP) and reduce the mass airflow through the early stages of the compressor, during acceleration from low engine speed thereby reducing the possibility of compressor stall and surge at low rpm.

  • To offload the compressor (LP and HP) and reduce the mass airflow through the early stages of the compressor, during acceleration from low engine speed thereby negating the possibility of compressor stall and surge at low rpm.

  • To offload the compressor (LP and HP) and increase the mass airflow through the early stages of the compressor, during acceleration from low engine speed thereby negating the possibility of compressor stall and surge at low rpm.

Question 28 of 32

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What positions are the surge/stall bleed valves or bleed bands during engine acceleration?

Select one or more of the following:

  • Open at low and increasing rpm, progressively closing as rpm increases to design rpm

  • Closed at low and increasing rpm, progressively opening as rpm increases to design rpm

  • Closed at high and increasing rpm, progressively opening as rpm increases to design rpm

  • Open at high and increasing rpm, progressively closing as rpm increases to design rpm

Question 29 of 32

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Do turbine engines use the same compressor bleed outlets for surge/stall protections as they do for environmental control systems?

Select one or more of the following:

  • No

  • Yes

Question 30 of 32

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What is the normal source of bleed air at high and moderate (climb and cruise) power settings?

Select one or more of the following:

  • The low pressure compressor

  • The high pressure compressor

  • The intermediate pressure compressor

  • Both the low and high pressure compressors in a two spool engine,, and all three of the low, intermediate and high pressure compressors in a three spool engine.

Question 31 of 32

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What is the normal source of bleed air at low (descent) power settings?

Select one or more of the following:

  • Both the low and high pressure compressors in a two spool engine,, and all three of the low, intermediate and high pressure compressors in a three spool engine.

  • The low pressure compressor

  • The high pressure compressor

  • The intermediate pressure compressor

Question 32 of 32

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What are the effects of bleeding air off the compressor for systems such as anti-icing?

Select one or more of the following:

  • Gas temperature increases, thrust reduces and SFC increases.

  • Gas temperature reduces, thrust reduces and SFC increases.

  • Gas temperature reduces, thrust reduces and SFC reduces.

  • Gas temperature increases, thrust reduces and SFC reduces.

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Turbine Engine Compressors

Andrew Lee
Quiz by , created about 1 year ago

Turbine Engine Compressors

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Andrew Lee
Created by Andrew Lee about 1 year ago
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