Compressor anti-stall systems.txt
Card Set Information
Compressor anti-stall systems.txt
compressor anti stall broten turbine powerplant
study notes for compressor anti stall section
The variable angle compressor stator vane system partially closes down on the compressor flow area at ____________________________________
Low power settings
When moving to the ____________________ position as power is applied, the variable vane system provides for smooth and rapid engine acceleration.
The vane angle changes in response to adjustments of _________________________.
The power lever
When the airflow is deflected by the variable vane system, it _________________________ to match the speed of the rotor blades.
Slows down axially
The vane position changes with __________________________________.
Inlet air temperature change
When a FADEC system controls the variable stator vane (VSV) schedule, the throttle lever angle (TLA) is an important input to the ______________________________.
Compressor pressure ratio is the compressor ratio between compressor inlet pressure and _______________________________________
Compressor outlet pressure
A situation in which the stall line becomes violated occurs when the _________________ value goes out of limits for a given RPM-Ms
CR (compression ratio)
What is the variable angle compressor stator vane system designed to do?
Prevent off-idle stalls
How does the variable angle compressor stator vane system assist the engine?
By maintaining the airflow angle-of-attack within the compressor
When ambient temperature is 30 degrees F., what will the variable vanes do?
Start to open at 60 % N2 speed and be fully open at 92 %
Similar to the variable vane system, the compressor bleed band system provides for ________________________________________
Rapid and stall-free engine acceleration
The bleed band is open at low power settings and _________________________________________
Fully closed at high power settings
Similar to the variable vane system, the bleed band system maintains a vector relationship between _____________________________________________
Airflow and compressor RPM
The bleed band linkage moves in conjunction with the _____________________________
When the bleed band is opened by the action of __________________, it allows compressor discharge air to bleed away and reduce the mass airflow to the combustor.
The JT8D engine bleed valve system _____________________________________ the amount of bleed air being dumped overboard on an RPM schedule
Does not meter
At high RPM the JT8D bleed valves are in ________________________________________
Fully closed position
The CFM-56 engine bleed valve system meters the amount of bleed air being dumped overboard in response to N2 speed and _________________________________________
Fan discharge temperature
The JT8D bleed valve system is a _____________________________________________
Two position bleed system
When Ps3 air pressure is greater than _______________, the bleed valves are closed.
When Ps4 pressure is venting the spring in the vent line, it causes the close line pressure to _____________
When the bleed band is open, it dumps rear compressor air overboard. What effect does this have on the front stage airflow?
It speeds up front stage air in the axial direction
If you want to check for correct operation of the bleed band, which cockpit indicator should you refer to?
RPM indicator for shift at opening and closing of the band
At 30 degrees F. Ambient temperature, how must the bleed band that is precisely on schedule perform?
If closed by 68% N1 speed on acceleration, it must reopen by 66% on deceleration
The engine anti-icing system ___________________________ ice formation at the engine inlet
Hot air is supplied to inlet anti-icing discharge ports from the rear stages of the ________________
Some larger engines are not fitted with an anti-ice system because they do not tend to form inlet ice due to the centrifugal effect of the _____________________
The regulator valve is placed in the anti-ice airflow line to prevent large quantities of hot air from entering the inlet at ____________________________________
High power settings
When anti-ice is selected, an indicator light illuminates in the cockpit and the ______________ gauge generally shows a slight rise
Inlet icing might occur at ambient air temperatures up to ___________
45 degrees F.
When the aircraft is in flight, anti-icing ____________________ usually required when ambient temperature is below 5 degrees F.
Inlet icing during engine ground run-up at high RPM is ______________ likely to happen at low ambient temperatures.
Inlet icing is most prevalent at which operating condition?
During ground high RPM run-up
What should you do if the engine is operating on the ground without anti-ice and you suspect that inlet ice buildup is causing a compressor stall?
Shut down the engine and clear the ice by external means
Compressor stall is caused by
A high angle of attack airflow through the first stages of compression
Operating thrust reverses at low ground speeds can sometimes cause
- Sand or other foreign object ingestion
- hot gas re-ingestion
- compressor stalls
Anti-icing of jet engine air inlets is commonly accomplished by
Engine bleed air ducted through the critical areas
On an aircraft turbine engine, operating at a constant power, the application of engine anti-icing will result in
Noticeable shift in EPR
What indications may shift when a turbofan engine anti-icing (bleed air) system is turned on?
The purpose of an engine/inlet anti-ice system is primarily to
Prevent ice formation in engine and/or inlet areas
What is the purpose of the variable stator vane system installed on some gas turbine engines?
To reduce the engine's tendency to stall on acceleration or deceleration at low or intermediate speed
How many vanes in a single stage have controllable angles?
An angle-of-attack relationship occurs at the compressor blade leading edge from inlet airflow and what other factor within the engine?
RPM effect on airflow
Is the compressor bleed system closed at takeoff power?
Where is the compressor bleed system air directed?
If an engine with a compressor bleed system experiences compressor stalls, what is the probable cause?
What FADEC system manages the operation of the electronic stator vane system?
The electronic engine control (EEC)
In a dual-spool engine, for which of the compressors (N1 or N2) does the variable stator vane system control airflow?
The N1 low pressure compressor
Is the anti-ice system designed to remove ice from the engine inlet?
No. It is designed to prevent ice formation.
Is the anti-icing regulator electrically controlled?
No. It is controlled by a bimetallic spring.
How does inlet ice cause a compressor stall?
Airflow is blocked or distorted into the compressor.
Does the heated air used in the anti-icing system come from the compressor or the combustor?
Is the inlet electro-thermal anti-icing system selected whenever ice conditions are present or only when the engine is running?
With the engine running