The Gas Turbine Engine Part 1 Flashcards
Four cycles of a gas turbine engine:
Induction
Compression
Combustion
Expansion
Thrust of a turbine can be calculated:
Thrust (t) = Ms (V2 - V1) / g
T = thrust in pounds
Ms = Mass flow per second
V1 = Inlet velocity
V2 = Jet velocity
g = gravitational acceleration
The four types of jet engines:
Turbojet
Turboprop
Turbofan
Turboshaft
The three types of compressors?
Centrifugal flow
Axial flow
Centrifugal-axil flow
The centrifugal flow compressor achieves compression of air by -
Accelerating it at right angles to the centre line of the engine
The axial flow compressor accelerates the flow along the -
centreline of the engine
The centrifugal-axial compressor -
combines the two effects
A spool is defined as -
a group of compression stages
What does this definition refer to:
The ability of the duct to convert kinetic energy at the duct inlet to static pressure energy at the compressor inlet without any loss in total pressure.
Duct pressure efficiency ratio
What does this definition refer to:
This is defined as the aircraft speed at which the ram rise pressure is equal to the frictional pressure losses.
Ram Recovery Point
The amount of air passing through the engine depends upon
- The compressor RPM
- Speed of the aircraft
- Density of the air
In a twin spool engine, the low pressure compressor is where the air -
enters the engine
In a twin spool engine, the high pressure compressor is located -
behind the low pressure compressor
The RPM of the low pressure compressor is entitled -
N1
The RPM of the high pressure compressor is entitled -
N2
Which negative effect:
This may be caused when the pressure demanded by the engine is greater than that which can be provided by the compressor blades. This results in an instantaneous breakdown of the airflow through the engine and the high pressure air in the combustion system is discharged forward through the compressor.
Compressor surge
A choke stall will occur when?
the reduction of RPM reduces the compression ratio; this reduced pressure results in a larger volume of air in the rear of the compressor which tends to choke the engine
factors that will increase the compressor blade angle of attack?
decreasing airflow velocity or increasing the RPM
if a compressor stall is suspected immediate action must be taken to clear it. This will include -
reducing the pressure in the combustion chamber by reducing the power setting, which will reduce the flow of fuel, and at the same time increasing the forward speed of the aircraft by pitching down.
Combustion chambers contain the following 5 basic elements:
- A casing
- Perforated inner linings
- A fuel ignition system
- Igniters
- An excess fuel drainage system
The reduction in velocity is achieved by the -
and the area where the burning takes place is called -
divergent diffuser shape of the forward part of the combustion chamber
The primary zone
The swirl vanes and flare disc serves what purpose?
To further reduce the velocity of air entering the combustion chamber
The percentage amount of airflow that is taken from main flow of air, by the swirl and flare disc leading to the primary zone??
20%
The amount of airflow taken from the main flow, that passes through the secondary air holes to the primary zone?
20%
The amount of airflow taken from the main flow, that passes around the primary zone entering the dilution air holes to cool burnt gases to a temperature acceptable to the turbine blades?
60%
Which type of combustion chamber:
In this type of arrangement the cans are arranged in a circle around the centreline of the engine area and usually individually removable which makes inspection and maintenance easier.
They take a lot of space and increase the frontal area.
Multiple combustion chamber
Which type of combustion chamber:
This chamber is essentially a single one formed from two concentric cylinders located around the centreline of the engine between the compressor outlet and the turbine. It is particularly suited to the axial flow engine where it makes the best use of available space and has low pressure loss. Theoretically, it is the most efficient burner chamber because, being a single large combustion chamber, the combustion process is achieved more evenly within the flame tube.
The annular combustion chamber
Which type of combustion chamber:
This appears similar at first glance to the multiple combustion chamber system. The significant difference is that instead of each flame tube having its own air casing, one common air casing encloses a number of flame tubes.
The can-annular or tubo annular
Which compressor type contains the following:
Compressor casing, or manifold, containing fixed air inlet guide vanes and outlet ports
The impeller
The diffuser(not the same as the same as the combustion chamber diffuser)
Centrifugal flow compressor
Which compressor type contains the following:
The compressor consists of an annular passage through which the air passes and across which are arranged a series of small blades of aerofoil section, alternately fixed to the outer casing or rotating on a central shaft assembly
One set of rotor and one set of stator blades constitute one stage of compression
The axial flow compressor
The compressor serves to?
The compressor squeezes the air that enters it into progressively smaller areas, resulting in an increase in the air pressure
