Control device for an engine
View Patent ↗An engine control device having a calculator for calculating a pitch setpoint for at least one propeller of the engine, the calculator taking account at least of a flight speed.
1. An engine control device, comprising:
a full authority digital engine control computer configured to calculate a pitch setpoint for at least one propeller of the engine using a propeller performance model that takes account at least of a flight speed in order to adapt a pitch setpoint while taking account of a shaft power setpoint, said propeller performance model being based on predicting losses associated with the operation of the propeller and an absorbed power coefficient.
2. A control device according to claim 1 , wherein a magnitude representative of a behavior of the propeller is determined using at least one polynomial of second or higher order.
3. A control device according to claim 1 , wherein a magnitude representative of a behavior of the propeller is determined as a function of a relative Mach number for a blade of the propeller and an assumed pitch for the propeller.
4. A control device according to claim 1 , wherein a speed of rotation of the propeller is input into the propeller performance model.
5. A control device according to claim 1 , wherein an assumption for a blade pitch is input into the propeller performance model.
6. A control device according to claim 1 , wherein the propeller performance model is implemented using an iteration loop having a stop criterion that is a calculated value for shaft power converging on a shaft power setpoint.
7. A turboprop including a control device according to claim 1 .
8. An unducted fan engine including a control device according to claim 1 .
9. A control device according to claim 1 , wherein the losses associated with the operation of the propeller is established using
{
Loss
=
Loss
ml
+
{
A
2
loss
choke
A
2
loss
stall
}
·
GH
2
GH
=
Jml
-
J
,
in which J is an advance ratio, Jml is an advance ratio for minimum loss, Loss ml is a minimum loss, A2 loss choke is a parabolic curve of loss for negative angles of incidence, and A2 loss stall is a parabolic curve of loss for positive angles of incidence,
Jml, Loss ml , A2 loss choke, and A2 loss stall are coefficients determined based on a blade pitch, the flight speed, and a speed of rotation of the propeller.
10. A control device according to claim 9 , wherein the absorbed power coefficient is established using
Cp
=
Cp
ml
+
A
1
·
GH
+
{
A2
Cp
choke
A
2
Cp
stall
}
·
GH
2
,
in which Cp is the absorbed power coefficient, Cp ml is an absorbed power coefficient on a minimum loss line, A1 is a first order coefficient of the model for the absorbed power coefficient, A2 cp choke is a parabolic curve of the absorbed power coefficient for negative angles of incidence, and A2 cp stall is a parabolic curve of the absorbed power coefficient for positive angles of incidence, and
Cp ml , A1, A2 cp choke, and A2 cp stall are coefficients determined based on the blade pitch, the flight speed, and the speed of rotation of the propeller.