BrakeSnake
6th Jan 2001, 02:38
I'd like to know if anyone out there can share any information they might have on engine surges, preferably from those of you who have actually experienced a surging civil turbofan engine.
I understand the theory behind the condition of surging, i.e that the engine is demanding a pressure rise which the compressor blading cannot sustain, resulting in airflow breakdown within the compressor and thus the reversal of flow which causes the hot high pressure combustion gases to be expelled through the front of the machine. This is seen on the test rigs as a cyclic rising of pressure in front of the machine, and a expulsion/suction of visible flames (accompanied by 'banging' noises) from the front of the compressor.
The engine has now begun to operate off its working line and has moved past the surge line into the unstable area of its operating envelope. Fine. All this theory is good. What i would like to know, is what indications you would expect to see on flightdeck instrumentation, and what sort of ambient/atmospheric conditions are required (combined with flight phase and type of performance demanded from engine) to make a MODERN engine susceptible to surging. If any of you out there could reply with info on your experiences of engine surges i would be extremely grateful. If the following could be included;
1)Aircraft type
2)Engine type
3)Flight phase (i.e climb)
4)Flight condtions (atmospheric)
5)Altitude
6)Speed
7)Engine demands
8)Flight deck indications before/ during/after surge (EPR, N1 trends etc)
9)Corrective action and outcome
I know that this sounds like a lot, but I would be very grateful as I recently encountered a not very nice engine shutdown over Spain and suspect it to be due to an irrecoverable engine surge condition.
Thanks for the help chaps.
Safe flying.
[This message has been edited by BrakeSnake (edited 05 January 2001).]
I understand the theory behind the condition of surging, i.e that the engine is demanding a pressure rise which the compressor blading cannot sustain, resulting in airflow breakdown within the compressor and thus the reversal of flow which causes the hot high pressure combustion gases to be expelled through the front of the machine. This is seen on the test rigs as a cyclic rising of pressure in front of the machine, and a expulsion/suction of visible flames (accompanied by 'banging' noises) from the front of the compressor.
The engine has now begun to operate off its working line and has moved past the surge line into the unstable area of its operating envelope. Fine. All this theory is good. What i would like to know, is what indications you would expect to see on flightdeck instrumentation, and what sort of ambient/atmospheric conditions are required (combined with flight phase and type of performance demanded from engine) to make a MODERN engine susceptible to surging. If any of you out there could reply with info on your experiences of engine surges i would be extremely grateful. If the following could be included;
1)Aircraft type
2)Engine type
3)Flight phase (i.e climb)
4)Flight condtions (atmospheric)
5)Altitude
6)Speed
7)Engine demands
8)Flight deck indications before/ during/after surge (EPR, N1 trends etc)
9)Corrective action and outcome
I know that this sounds like a lot, but I would be very grateful as I recently encountered a not very nice engine shutdown over Spain and suspect it to be due to an irrecoverable engine surge condition.
Thanks for the help chaps.
Safe flying.
[This message has been edited by BrakeSnake (edited 05 January 2001).]