AMT Turbine Engine Principles Questions and Answers

Question 1

The operation of a gas turbine engine is described by the Brayton cycle. Which of the following represents the correct sequence of the four events in an ideal Brayton cycle?

Accepted Answer

Compression, Combustion, Expansion, Exhaust

Answer

The ideal Brayton cycle consists of four processes: isentropic compression (in the compressor), constant-pressure heat addition (in the combustor), isentropic expansion (in the turbine), and constant-pressure heat rejection (exhaust). This is best summarized as Compression, Combustion, Expansion, and Exhaust.

Question 2

In a gas turbine engine, what is the primary function of the diffuser section located between the compressor and the combustion chamber?

Accepted Answer

To decrease the velocity and increase the pressure of the air.

Answer

The diffuser is a duct with an expanding internal diameter. Its purpose is to slow down the high-velocity air leaving the compressor, converting its kinetic energy into potential energy in the form of increased static pressure. This high-pressure, low-velocity air is ideal for efficient combustion.

Question 3

Which of the following is a primary advantage of an axial-flow compressor compared to a centrifugal-flow compressor in large, high-performance turbine engines?

Accepted Answer

Greater efficiency and ability to handle high mass airflow.

Answer

Axial-flow compressors are capable of handling a very large mass of air for a given frontal area and can achieve very high overall compression ratios with high efficiency through multiple stages. This makes them ideal for large engines where high thrust and fuel efficiency are required. Centrifugal compressors typically have a higher pressure rise per stage but are limited in overall mass airflow and are less efficient in very large applications.

Question 4

A modern commercial airliner is typically powered by high-bypass turbofan engines. What is the main benefit of having a high bypass ratio?

Accepted Answer

Improved fuel efficiency and reduced engine noise.

Answer

In a high-bypass engine, a large volume of air is accelerated by the fan and bypasses the engine core. This large mass of slower-moving air produces the majority of the thrust more efficiently than a smaller mass of high-velocity gas from the core. This results in significantly better thrust-specific fuel consumption (fuel efficiency) and lower noise levels.

Question 5

While a gas turbine engine's ultimate purpose is to produce thrust, what is the primary role of the turbine section within the engine?

Accepted Answer

To extract energy from the hot gases to drive the compressor and accessories.

Answer

The primary function of the turbine section is to extract kinetic and thermal energy from the high-velocity gases leaving the combustion chamber. This extracted energy is converted into mechanical work to rotate the main shaft, which in turn drives the compressor section and engine-driven accessories like fuel pumps and generators.

(AMT) Aviation Maintenance Technician Practice Test

(AMT) Aviation Maintenance Technician Practice Test

AMT Turbine Engine Principles Questions and Answers