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71. In a compressor, diffusion action takes place across.
A. rotors.
B. rotors and stators.
C. stators.
72. The ring of fixed blades at the intake of an axial flow compressor are called.
A. inlet guide vanes.
B. first stage stator blades.
C. first stage diffuser blades.
73. What is the purpose of pressure balance seal?.
A. To ensure the location bearing is adequately loaded throughout the engine thrust range.
B. To ensure LP compressor is statically balanced.
C. To ensure HP compressor is dynamically balanced.
74. The optimum air speed for entrance into the compressor is approximately.
A. same as aircraft speed.
B. Mach 0.4.
C. Mach 1.
75. What is the acceptable damage on stator blades that have been blended?.
A. One third along from root to tip.
B. One third from tip to root.
C. One third chord wise.
76. With regard to compressor blades, which of the following is true? No damage is permissible on.
A. a shroud fillet area.
B. the lip of a blade.
C. the last third of the outboard leading edge.
77. Identify a function of the cascade vanes in a turbojet engine compressor section.
A. To remove air swirl before the combustion chamber.
B. To direct the flow of air to strike the turbine blades at a desired angle.
C. To decrease the velocity of air to the combustor.
78. The pressure ratio can be influenced by.
A. compressor inlet temperature.
B. number of stages in compressor.
C. compressor inlet pressure.
79. Air bleed valves are.
A. closed at low RPM.
B. open at high RPM.
C. open at low RPM.
80. The compressor case annulus is.
A. convergent.
B. divergent.
C. parallel.
ABOVE QUESTIONS WITH ANSWERS
71. In a compressor, diffusion action takes place across.
A. rotors.
B. rotors and stators.
C. stators.
72. The ring of fixed blades at the intake of an axial flow compressor are called.
A. inlet guide vanes.
B. first stage stator blades.
C. first stage diffuser blades.
73. What is the purpose of pressure balance seal?.
A. To ensure the location bearing is adequately loaded throughout the engine thrust range.
B. To ensure LP compressor is statically balanced.
C. To ensure HP compressor is dynamically balanced.
74. The optimum air speed for entrance into the compressor is approximately.
A. same as aircraft speed.
B. Mach 0.4.
C. Mach 1.
75. What is the acceptable damage on stator blades that have been blended?.
A. One third along from root to tip.
B. One third from tip to root.
C. One third chord wise.
76. With regard to compressor blades, which of the following is true? No damage is permissible on.
A. a shroud fillet area.
B. the lip of a blade.
C. the last third of the outboard leading edge.
77. Identify a function of the cascade vanes in a turbojet engine compressor section.
A. To remove air swirl before the combustion chamber.
B. To direct the flow of air to strike the turbine blades at a desired angle.
C. To decrease the velocity of air to the combustor.
78. The pressure ratio can be influenced by.
A. compressor inlet temperature.
B. number of stages in compressor.
C. compressor inlet pressure.
79. Air bleed valves are.
A. closed at low RPM.
B. open at high RPM.
C. open at low RPM.
80. The compressor case annulus is.
A. convergent.
B. divergent.
C. parallel.
ABOVE QUESTIONS WITH ANSWERS
71. In a compressor, diffusion action takes place across.
A. rotors.
B. rotors and stators.
C. stators.
Ans : rotors and stators.
Explanation: Stators and rotors in compressors both form divergent ducts hence they both diffuse.
72. The ring of fixed blades at the intake of an axial flow compressor are called.
A. inlet guide vanes.
B. first stage stator blades.
C. first stage diffuser blades.
Ans : inlet guide vanes.
Explanation: The fixed IGV's precede the 1st stage rotor which is in front of the 1st stage stator.
73. What is the purpose of pressure balance seal?.
A. To ensure the location bearing is adequately loaded throughout the engine thrust range.
B. To ensure LP compressor is statically balanced.
C. To ensure HP compressor is dynamically balanced.
Ans : To ensure the location bearing is adequately loaded throughout the engine thrust range.
Explanation: Pressure balance seals oppose the tendency of compressors to move forward.
74. The optimum air speed for entrance into the compressor is approximately.
A. same as aircraft speed.
B. Mach 0.4.
C. Mach 1.
Ans : Mach 0.4.
Explanation: Diffusion in the intake reduces the speed to 500ft/second (about mach 0.4).
75. What is the acceptable damage on stator blades that have been blended?.
A. One third along from root to tip.
B. One third from tip to root.
C. One third chord wise.
Ans : One third from tip to root.
Explanation: The root of the blade has tighter tolerance than the tip, and chord wise indentations are also critical so our best guess is from tip to root
76. With regard to compressor blades, which of the following is true? No damage is permissible on.
A. a shroud fillet area.
B. the lip of a blade.
C. the last third of the outboard leading edge.
Ans : a shroud fillet area.
Explanation: Shroud fillets are critical areas whereas the outer third of the blade is less so. Unshrouded tips are also less critical than shroud fillets.
77. Identify a function of the cascade vanes in a turbojet engine compressor section.
A. To remove air swirl before the combustion chamber.
B. To direct the flow of air to strike the turbine blades at a desired angle.
C. To decrease the velocity of air to the combustor.
Ans : To remove air swirl before the combustion chamber.
Explanation: Jeppesen Aircraft Gas Turbine Powerplants page 3-23 describe the axial flow compressor as containing sets of airfoils in cascade'. It further says that the last stage of stationary vanes, called exit guide vanes turn the airflow back to an axial direction on its way to the combustor.
78. The pressure ratio can be influenced by.
A. compressor inlet temperature.
B. number of stages in compressor.
C. compressor inlet pressure.
Ans : number of stages in compressor.
Explanation: Compressors are rated by their pressure ratio, the more stages the greater the pressure ratio.
79. Air bleed valves are.
A. closed at low RPM.
B. open at high RPM.
C. open at low RPM.
Ans : open at low RPM.
Explanation: Air bleed valves reduce the pressure developed in a compressor until the speed is increased towards the blade design speed.
80. The compressor case annulus is.
A. convergent.
B. divergent.
C. parallel.
Ans : convergent.
Explanation: All axial flow compressor case annulus are convergent to maintain a constant axial velocity through the compressor.
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