Results
Q1. The pressure ratio of a gas turbine engine compressor is:
Correct answer is – equal to the number of compression stages
Q2. The compressor idling speed of an uncompensated gas turbine engine will increase:
Correct answer is – at higher ambient temperature
Q3. One stage of an axial flow compressor consists of:
Correct answer is – one rotor assembly and one row of stator vanes
Q4. The pressure rise across each stage of an axial flow compressor is:
Correct answer is – between 1.1 and 1.2 to one
Q5. The ring of blades which sometimes precede the first rotor stage of an axial flow compressor are called:
Correct answer is – variable inlet guides vanes
Q6. As air passes through an axial flow compressor, a pressure rise takes place in:
Correct answer is – both the rotor blades and the stator vanes
Q7. In the event of a surge occurring the correct action to be taken is:
Correct answer is – to close the throttle slowly
Q8. Shrouding of stator blade tips is designed to:
Correct answer is – minimize vibration
Q9. The cross-sectional area of the air annulus is reduced as it approaches the combustion chamber:
Correct answer is – to maintain the axial velocity of the air toward the combustion chamber
Q10. The attachment of blades to the compressor disc:
Correct answer is – is rigid
Q11. Compressor blades are designed to produce:
Correct answer is – a steady velocity with a pressure rise over the engine speed range
Q12. A compressor blade will stall when:
Correct answer is – the air axial velocity and rotational speed relationship is disturbed
Q13. Compressor surge will occur when:
Correct answer is – all stages are at maximum rpm
Q14. Cascade vanes are fitted in which part of the centrifugal compressor?
Correct answer is – the outlet elbow
Q15. The purpose of the diffuser vanes in a centrifugal compressor is to:
Correct answer is – convert kinetic energy into pressure energy
Q16. The pressure rise across a centrifugal compressor:
Correct answer is – is shared almost equally by the impeller and the diffuser
Q17. To gain a greater pressure ratio than 4:1:
Correct answer is – two centrifugal compressors can be placed in series with each other
Q18. The major disadvantage of a centrifugal compressor is that:
Correct answer is – it cannot cope with a large mass flow of air
Q19. The purpose of cascade vanes is to:
Correct answer is – turn the air smoothly through 90 degrees and complete diffusion
Q20. The type of compressor used to create radial airflow would be:
Correct answer is – centrifugal
Q21. Under ideal conditions the pressure rise across a single-stage centrifugal compressor can be:
Correct answer is – not more than 4 to 1
Q22. An advantage of a centrifugal compressor is that it is:
Correct answer is – more robust and is easier to manufacture
Q23. A compressor stall causes:
Correct answer is – an increase in the turbine gas temperature and the vibration level
Q24. Air passing through a convergent duct experiences:
Correct answer is – a decrease in temperature and pressure with an increase in velocity
Q25. Fuel is regulated on rapid engine acceleration:
Correct answer is – to prevent inducing a compressor stall and surge
Q26. A compressor stall:
Correct answer is – may only affect one stage or several stages of a compressor
Q27. Compressor blades increase in size:
Correct answer is – from the high pressure section of the compressor to the low-pressure section
Q28. The occurrence of compressor stalls is limited by:
Correct answer is – bleed valves
Q29. Bleed valves are automatically opened:
Correct answer is – at low engine rpm to prevent the compressor stalling
Q30. To prevent compressor stall at the rear of the compressor, bleed valves must be positioned:
Correct answer is – at the mid stages of the compressor
Q31. A complete breakdown of airflow through a compressor is known as:
Correct answer is – compressor surge
Q32. One indication that a compressor bleed valve has stuck closed at low rpm is:
Correct answer is – possible compressor stall
Q33. Within the compressor:
Correct answer is – temperature increases
Q34. Bleeding compressor air for anti-icing will cause:
Correct answer is – an increase in EGT, a decrease in thrust and an increase in SFC
Q35. Variable inlet guide vanes:
Correct answer is – adjust the relative airflow position
Q36. Compressor blades are twisted from root to tip:
Correct answer is – to maintain a correct angle of attack
Q37. In a compressor:
Correct answer is – the air temperature rises with a pressure rise
Q38. A stall in a gas turbine engine is most likely to occur with: (Pressure Ratio / Location in Compressor)
Correct answer is – low / back
Q39. Contamination of the compressor:
Correct answer is – can seriously reduce the efficiency of the engine
Q40. The low pressure compressor of a high ratio bypass engine:
Correct answer is – is driven by the rearmost turbine
