Main-Engine Components Flashcards
In a gas turbine engine, a diffuser is used to reduce the velocity of gas entering the combustion chamber, to?
Increase the gas pressure and ensure that the combustion does not stop.
What is the main purpose of a diffuser?
To reduce the velocity of gas into the combustion chamber.
The disadvantages of axial flow compressors compared to centrifugal flow compressors are that they?
Are more expensive to manufacture and have greater vulnerability to foreign object damage.
What is the primary purpose of the exhaust section of a turbojet engine?
To direct the flow rearward and ensure a high velocity of the hot exhaust gases.
In an axial flow compressor, a stage has a compression ratio of?
1.2:1
A vent valve in the combustion chamber of a gas turbine engine does what?
Allows leftover fuel to drain out of the bottom of the combustion chamber.
One of the main functions of inlet guide vanes in gas turbine engines is to?
Prevent compressor stalls during engine acceleration and deceleration
The purpose of a compressor bleed valve in a gas turbine engine is to?
Prevent surging at low compressor rpm.
In a turbo-jet, the purpose of the turbine is to?
Drive the compressor by using part of the energy from the exhaust gases.
In subsonic airflows, the convergent exhaust unit is designed to convert?
Pressure into speed.
Why is the jet engine exhaust convergent?
To accelerate the exhaust air.
The internal geometry of turbofan intake for a subsonic commercial aeroplane is?
Divergent in order to reduce airflow velocity and increase static pressure in front of the fan.
The average stage compression ratio of a centrifugal compressor is approximately?
4:1
The compression blades in a rotating gas turbine engine are held in position by?
The mountings, and centrifugal force.
The rotor blades of an axial compressor of a gas turbine engine are often mounted on a disk or drum using a ‘loose fit’ because?
This limits damage to the blades due to vibration.
Engine temperature limitations of a gas turbine engine are usually imposed due to temperature limitations on the?
Turbine section.
The function of an exhaust-propelling nozzle is to?
Increase the exhaust gas velocity, resulting in additional thrust.
Compressor surge in a gas turbine engine may be prevented by means of?
Bleed valves.
Compressor stall in a gas turbine engine is due to?
An excessively high angle of attack of the rotor blades.
In a compressor stage of a gas turbine engine, if the dial air velocity increases more than the rotor blade velocity the stall margin will?
Increase
In a turbine engine, the airflow is slowed down at the diffuser to prevent the combustion chamber flame from being inhibited by?
Too high dynamic pressure.
The average stage compression ratio of an axial compressor is approximately?
1.1 - 1.4:1
The primary function of the diffuser, located between the compressor and the combustion chamber, of a gas turbine engine is to?
Decrease the flow velocity.
In a gas turbine engine, the Inlet Guide Vanes (IGV)?
Direct the airflow at the optimal angle to the compressor’s first stage
