QUOTE(JohnMax @ Jul 27 2009, 11:13 PM)
Droop CompensatorWhen the helicopter rotor system power requirements increase, the N2NR RPM tends to decrease.
The reverse is true when the rotor system power requirements are decreased.
It is desirable to vary the rotor system power requirements without having to change the N2NR RPM.
In order to prevent an N2NR RPM variation when a power change is made, a droop compensator is provided.
The Droop Compensator resets the power turbine governor spring during a power change to keep the N2NR RPM as it was before the power change.
This allows the operator to increase the power delivered to the rotor system as the collective pitch is increased, while the N2NR RPM is maintained.
From what i understand, basically in a two spool configuration, there's:
N1 = gas producer speed/rpm
N2 = power turbine (free-turbine) speed/rpm
In nature, the N2 tends to decrease whenever N1 (power) is increased. And when N1 decreased, then N2 tends to increase.
So in this case (rotor system), the droop compensator is installed to maintain and stabilize the N2 rpm; as power is increased or decreased by the collective movement.
Droop compensation is achieved by a linkage attached to a bellcrank of the collective pitch control. The purpose of this linkage is to change the (power turbine) governor position mechanically to anticipate the required action as the collective is moved. If the movement was not anticipated as collective is raised, the N2 system would slow down, thus the term
droop.
QUOTE(destroyer @ Jul 28 2009, 02:10 AM)
study about aircraft engine a bit in my therodynamic subject since some ship do use gas turbine engine(a type of engine which is almost similar to aircraft engine just a bit different in design)<<--for aircraft is turbojet engine if i'm not mistaken.
Yup, aircraft uses turbojet. Airliners uses turbofan as it is relatively the most quiet in operation and very fuel efficient.
I believe sea vessels (ships) employ the turboshaft type.