AME Gas Turbine Engine Theory 2

Question 1

In a gas turbine engine, where does the highest total pressure in the gas path occur?

Accepted Answer

At the compressor discharge (diffuser outlet)

Answer

Total pressure peaks at compressor discharge and drops slightly through the combustor due to flow losses.

Question 2

What is the primary purpose of the diffuser section located between the compressor and combustor?

Accepted Answer

Decrease velocity and increase static pressure

Answer

The divergent diffuser slows airflow so the flame can be stabilized and static pressure rises.

Question 3

Approximately what percentage of the air entering a typical combustor is used directly for combustion (primary air)?

Accepted Answer

About 25%

Answer

Roughly 25% is primary combustion air, while about 75% is secondary air used for cooling and dilution.

Question 4

Which change in ambient conditions will increase the thrust output of a turbojet engine?

Accepted Answer

Lower outside air temperature

Answer

Colder air is denser, increasing mass airflow and thrust.

Question 5

What is the function of the nozzle guide vanes located ahead of the first turbine stage?

Accepted Answer

Accelerate the gases and direct them at the correct angle onto the turbine blades

Answer

The convergent passages of the NGVs raise velocity and set the correct flow angle for the turbine blades.

AME - Aircraft Maintenance Engineer Practice Test