Turbomachine flameout confirmation
Methods and apparatus are provided for detecting a flameout of an operating turbomachine that is configured to receive a controlled flow of bleed air from a bleed air source and a controlled flow of fuel from a fuel source. A value of an operational parameter within the turbomachine is detected and a determination is made as to whether it has varied by a predetermined amount. If the operational parameter has varied by the predetermined amount, a flameout confirmation test is triggered. The flameout confirmation test includes holding the controlled flow of bleed air constant, commanding an increase in turbomachine speed, and confirming that a flameout has occurred by detecting that the controlled fuel flow to the turbomachine is at a maximum fuel flow limit and that actual turbomachine speed differs from the commanded turbomachine speed by a predetermined speed error.
1. A method of detecting a flameout of an operating turbomachine that is configured to receive a controlled flow of bleed air from a bleed air source and a controlled flow of fuel from a fuel source, the method comprising the steps of:
detecting that a value of an operational parameter within the turbomachine has varied by a predetermined amount; and
triggering a flameout confirmation test that comprises the steps of:
holding the controlled flow of bleed air constant,
commanding an increase in turbomachine speed,
confirming that a flameout has occurred by detecting that (i) the controlled fuel flow to the turbomachine is at a maximum fuel flow limit and (ii) actual turbomachine speed differs from the commanded turbomachine speed by a predetermined speed error.
2. The method of claim 1 , wherein the operational parameter is one of a turbomachine speed error or a rate of change of a turbomachine temperature.
3. The method of claim 2 , wherein the turbomachine temperature is turbomachine exhaust gas temperature.
4. The method of claim 2 , wherein the predetermined rate of change is a negative value.
5. The method of claim 1 , further comprising:
attempting to relight the turbomachine if (i) the flameout is confirmed and (ii) a parameter associated with operation of the turbomachine is at least a predetermined value.
6. The method of claim 5 , wherein the parameter associated with operation of the turbomachine is one of the predetermined speed error or the controlled flow of bleed air is at a limit.
7. The method of claim 1 , further comprising:
determining that the value of the operational parameter within the turbomachine has varied by the predetermined amount for at least a predetermined time.
8. The method of claim 1 , further comprising selectively preventing the flameout confirmation test from being triggered regardless of whether the operational parameter has varied by the predetermined amount.
9. The method of claim 8 , further comprising:
a) determining if turbomachine exhaust gas temperature is rising;
b) determining if turbomachine exhaust gas temperature is at a predetermined temperature limit;
c) determining if turbomachine rotational speed is at a predetermined speed limit;
d) determining if the bleed air source is undergoing a transient; and
e) preventing the flameout confirmation test from being triggered if one or more of a)-d) is true.