Q04 Gas Turbines

Question 1

The mixture of impulse and reaction blade shape in the average turbine blade is such that:

Select one:

a.The root is impulse and towards tip is reaction.

b.The root is reaction and towards tip is impulse.

c.The leading edge is reaction and the trailing edge is impulse

d.The trailing edge is reaction and the leading edge is impulse.

Answer 1

a.The root is impulse and towards tip is reaction.

Question 2

A gas turbine engine turbine section may use active clearance control…

Select one:

a.As a method of attaching the stators and rotors to the hub of the disc

b.In order to cool the disc

c.In order to reduce ‘creep’ in the blades

d.To provide minimum clearances between the blade tips and the casing

Answer 2

d.To provide minimum clearances between the blade tips and the casing

Question 3

Which part of a gas turbine engine limits the operating temperature?

Select one:

a.exhaust

b.turbine

c.combustion chamber

d.compressor

Answer 3

b.turbine

Question 4

Which statement is true regarding Free Turbines

Select one:

1.They drive all the loads and compressors in the engine.

2.Free turbines don’t drive a compressor and can run at a constant speed

3.They are never used in turbo prop engines and they are never used to drive a compressor.

4.They drive all the compressors in the engine.

Answer 4

2.Free turbines don’t drive a compressor and can run at a constant speed

Question 5

In a free turbine engine;

Select one:

a.the compressor and power output shaft are mechanically connected

b.the air enters the compressor via the input turbine

c.there is no mechanical connection between the compressor and the power output shaft

d.its shaft may be connected to either a compressor or another turbine

Answer 5

c.there is no mechanical connection between the compressor and the power output shaft

Question 6

In a three spool turbofan engine, the fan is driven by which turbine:

Answer 6

rearmost

Question 7

Unless you want to believe someone else who’s banking it, the sequence of Pressure and Velocity in a Pure Reaction Turbine is;

a.NGV P same V same Rotor P decrease V decrease

b.NGV P same V same Rotor P decrease V increase

c.Rotor P same V same NGV P decrease V increase

d.NGV P decrease V increase Rotor P decrease V increase

Answer 7

b.NGV P same V same Rotor P decrease V increase

Question 8

With regard to a turbine, select the correct statements from the following;

a.Overall, Pressure, Velocity and Temperature drop through the turbine.

b.The pressure can go up or down

c.Stages are sometimes divergent

d.The root of the rotor blades is impulse

Answer 8

a.Overall, Pressure, Velocity and Temperature drop through the turbine.

Question 9

With regard to the following statements;

1. In the turbine, sometimes through the Rotor, velocity decreases.
2. Through the straight duct parts of the turbine, PV and T remain constant.

a.1. Incorrect 2. Correct.

b.Both Statements are correct.

c.1. Correct 2. Incorrect

d.Both statements are incorrect.

Answer 9

c.1. Correct 2. Incorrect