Week 6 Flashcards
These anti compressor stall systems are mechanical valves located on the outside of the compressor
Variable Bleed Valves
Which percent RPM do Variable Bleed Valves prevent stalls?
Below 91% RPM
At high RPM, are VBV’s closed or open?
Closed
What happens if the diaphragm is ruptured on the VBV?
Bleed Valve stays open longer
What happens if Convergent-Divergent Orifice is restricted or blocked?
Bleed Valve stays closed
Which engines are variable bleed valves found on?
PT-6
These anti compressor stall systems use a band around the rear stages of the compressor
Variable Bleed Bands
Larger turbofans require which types of bleed methods?
Pressure Ratio Bleed Control System
Which system is used on the JT8D?
3 Bleed Valves through a Pressure Ratio Bleed Control System(2 on 13th stage, one on 8th stage comp)
Which position will bleed valves be at idle?
Fully open
How do larger turbofan engines bleed compressor air?
Bleed Valves are located around the circumference of the N1 compressor and vent some of the N1 Bleed air into the fan duct.
How do Transient Bleed Valves operate?
Vent air from last stages of High Pressure Compressor back to first stage turbine vanes
Which system does the CF-6 Use?
VIGV and VSV
How do we reduce friction in the CF-6 VIGV and VSV?
Rotate within teflon sockets
How does the CF-6 System work?
FCU controlled. The actuators are connected to beams. The beams in turn are connected to rings that are attached to the individual vanes of the compressor.As you advance the throttle, fuel pressure moves the actuator, which moves the beam, which moves the rings that move the vanes.
