Aircraft Engines Lecture Notes

These flashcards cover key concepts and technical details regarding aircraft engines, their components, and principles of operation from the provided lecture notes.

What is required for an aircraft to take off vertically?

Thrust must be enough to overcome the weight of the aircraft.

What supplies thrust in aircraft engines?

A suitable type of aircraft heat engine.

What does thrust in an aircraft need to counteract for level flight?

Drag.

What law of motion explains thrust production in aircraft?

Newton's third law of motion.

What are turbojets, ramjets, and pulse jets examples of?

Engines that accelerate smaller quantities of air through large velocity changes.

How is the thrust horsepower (thp) calculated?

Thp = thrust x aircraft speed (mph) / 375.

What is meant by specific weight of an engine?

Weight of an engine per brake horsepower.

What do the terms 'reliability' and 'durability' signify in aircraft engines?

Reliability: Mean time between failures; Durability: Mean time between overhauls.

What are the primary functions of the accessory section in gas turbine engines?

Mounting accessories necessary for operation and control, and providing space for functionally essential components.

What must the combustion section of a gas turbine engine do?

Burn the air-fuel mixture to raise the temperature of the air passing through the engine.

What is the principle behind gas turbine engines providing thrust?

For every action, there is an equal and opposite reaction.

What do you call the temperature difference that affects turbine blade life?

Turbine inlet temperature.

How does increasing the ambient air pressure affect engine performance?

It generally increases thrust due to higher mass airflow.

What are two methods for improving thrust in gas turbine engines?

Increasing mass flow of air or increasing gas velocity.

What does 'ram pressure' refer to in the context of aircraft engines?

Pressure rise at the engine inlet due to forward aircraft speed.

What is the major efficiency issue that affects turbojet engines in airliner operations?

Noise and fuel consumption.

What is the design characteristic of turbofan engines that enhances fuel efficiency?

Large fan producing most of the thrust.

Which types of compressors are used in gas turbine engines?

Centrifugal flow and axial flow.

What is the basic concept of the Brayton cycle?

A thermodynamic cycle involving continuous combustion.

How does the design of the exhaust nozzle affect turbine engine performance?

It must direct hot gases rearward to prevent turbulence and ensure high exit velocity.

In terms of engine maintenance, what kind of agreements exist regarding powerplant reliability?

Standards agreed upon by the FAA, engine manufacturers, and airframe manufacturers.

What are the main components of the combustion section in gas turbine engines?

Casing, perforated inner liner, fuel injection system, ignition means, and fuel drainage system.

How are connecting rods classified?

Plain, fork and blade, master and articulated, split-type.

What caused the use of high bypass ratios in turbofan engines?

To create a larger mass of slower moving air that produces thrust effectively.

What is the effect of compressor efficiency on thermal efficiency in gas turbines?

Higher efficiencies reduce waste heat and improve engine performance.

What happens to turbine efficiency as air speed increases?

The thrust initially decreases due to increased ram drag, but may recover with more air mass entering the engine.