d Both a and b 485 Louvers in the flame tube are provided to a Prevent carbon

D both a and b 485 louvers in the flame tube are

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, d) Both a and b. 485- Louvers in the flame tube are provided to : a) Prevent carbon deposits. , b) Cool the liner. c) Admit fresh air for burning throughout the length of the flame tube. d) Both a and b . 486- Which of the following statement is wrong: a) 25% of the total air is used for initial combustion. b) Approx 75% of the air is used for cooling the flame tube . , c) The combustion chamber reduces the air velocity . d) Annular combustion chamber is more efficient than the can type . 487- Fuel scheduling for duplex fuel nozzle is done by: a) Fuel shut off cock. b) Throttling valve. , c) Fuel pressurizing valve . d) Fuel control unit.
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46 488- The purpose of the nozzle guide vanes: a) Is to extract kinetic energy from the gas flow. b) Is to be variable in front of the turbine blades. , c) Is to increase the velocity and direct the gas on to the turbine. d) Rotate at constant rpm. 489- Impulse reaction blading : a) Receives an impulse force only. b) Receives a pressure force only. , c) Receives a reaction force and impulse force . d) All the answers are correct. 490- Nozzle guide vanes: a) Are of airfoil shape and form divergent ducts. b) Are usually hollow for good lubrication. c) Are located in the turbine casing by the “fir tree” method. , d) In groups, may be called a nozzle diaphragm. 491- The turbine disc: a) Is a machined casting with integral shaft and flange. b) Houses the turbine blades by the De- Laval method. c) May be connected to the compressor directly with out any shaft. , d) is cooled by HP air. 492- Air seals on the discs are located: a) To control cooling air flowing down the disc. b) To prevent gas flow escape. , c) To control HP cooling airflow up the disc . c) To prevent oil leakage. 493- Shrouding of the turbine blades: a) Increases the blade weight. , b) Permits thinner blade sections . c) Helps to increase the gas leakage past the tips of the blades. d) All the answers are correct . 494- What is creep of the turbine blades : a) Loss of elasticity. b) Elongation of the blade . c) Growth of the blade due to centrifugal and thermal stresses . , d) All the answers are correct . 495- In a gas turbine engine the purpose of a turbine is to: a) Convert heat energy into mechanical work. b) Blow out the exhaust gases. c) Drive the compressor and accessories. , d) a and c . 496- The result of turbine blade creep is: a) High T.G.T , b) Blade seal rub. c) N.G.V seal rub. d) Immediate engine failure. 497- Which of the following statements is true: , a) Turbine blades are attached by the “fir - tree” method. b) Shrouding increases the total blade weight. c) Non- shrouded blades have thinner cross section. d) Cold turbine blades have no movement .
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47 498- Which statement is true? a) High T.G.T can cause a change in blade pitch. b) No creep is allowed on the turbine blades. , c) LP turbine disks are cooled by LP air. d) N.G.Vs are hollow for lightness. 499- Cracking of turbine blades will first occur on: , a) Trailing and leading edges .
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  • Summer '17
  • sajad heidari
  • compressor, RPM, gas turbine engine, Axial compressor

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