The bleed scheduler offers flexible control for off-design bleed control using corrected rotor speed schedules. Use this component for specifying variable bleed (e.g. for analysis of bleed flow effects) based on a corrected spool speed using a predefined schedule. Any type of compressor bleed flow can be controlled (e.g. customer bleed, handling bleed, turbine cooling bleed flows etc.).
Either absolute bleed mass flow or relative bleed mass flow (relative to total compressor entry mass flow) can be scheduled as function of the corrected rotor speed.
Corrected rotor speed is either
•Shaft Nc (1st component entry conditions)
The shaft corrected rotor speed is taken for the schedule input Nc. This is the rotor speed of she specified shaft corrected to ISA from the entry conditions of the first component in the gas path on the shaft, usually the compressor that the bleed is coming from. However, depending on your component and shaft configuration, this is not necessarily the corrected shaft speed of the compressor delivering the bleed, as would for example be the case if there is an upstream separate compressor on the same shaft.
•Corrected for ambient total conditions
The rotor speed of she specified shaft is corrected to ISA from the total (for aircraft 'ram') conditions in the undisturbed flow upstream the engine.
Note that the schedule must be descending and the grid does not extrapolate. Outside the input range the output value stays at the level closest within the schedule.
The mass flow scheduled value can also be specified as
•uncorrected (default)
•corrected to the component entry conditions,
•corrected to total (for aircraft 'ram') conditions in the undisturbed flow upstream the engine
If corrected, the mass flow resulting from the schedule is 'uncorrected' in order to determine the actual mass flow to be taken from the bleed..
Bleed Schedule Control
