What is a compressor stall in a jet engine?

Question

What is a compressor stall in a jet engine?

Answer 1

the flow along blades of compressor rotor is governed by the pressure difference. if there is too much air behind the compressor stage, the resultant leaving air vector becomes perpendicular to rotational speed of the compressor stage. THAT makes the blades of compressor stage to work in high angle of attack, and causes flow separation on them. flow separation reduces the duct cutthrough area between the blades, thus reducing the volume of air passing through the stage even more.



the compressor happens to freewheel in the volume of air and may even leak the pressure in OTHER way.



http://s624.photobucket.com/albums/tt330/mindworms/?action=view¤t=PICT5479.jpg



with imagine what happens to the flow as the Va drops.

NB, the AoA at the leading edge (the front edge of the blade)depends by large on the flow shaping from precedessing stator stage (and rotational speed, again - that's why advanced engines have moving stator vanes)



last but not least, the vector depicted is the air flow FROM THE BLADES perspective. the air on its own just moves at the Va speed. the Vr is there for the sake of studying flow on the rotating blade.

Answer 2

Think of a compressor stall being similar to a wing stall A wing will stall when the air flow across it so messed up that air will not generate lift. The same is true for the compressor blades inside a jet engine. You do something weird to the plane and cause an interrupted flow of air into the engine and the compressor blades will stall out. The perfect example is the bird strikes that precipitated the Miracle on the Hudson. Side-slipping a jet can cause the disruption of the air flow into the engine and cause a compressor stall. A female F-14 driver was trying to correct for poor line-up at the boat, did a side-slip, the port engine stalled and quit in close and set hit the round down on the boat. In her case, a fatal mistake. Another instance a F-14 was showing off and made a high speed pass at the boat. He snapped the nose up, had a compressor stall and the bird exploded. If you take care of your bird, your bird will bring you home in one piece. Abuse it and it will kill you without a moment of hesitation.

Answer 3

Compressor Stall

Answer 4

Compressor stalls occur when there is an airflow problem at the inlet of the engine. This may the ingestion of dirt or birds, or even of a person. (You can see an excellent example of this on U-Tube in one of the naval carrier videos, where a ground mechanic gets sucked into an inlet, and the engine immediately compressor stalls and spits him back out.) (He survived) I know of another case with a Honeywell TFE731 engine where the tech was sucked into it, and his parka was rubbing on the round nose spinner of the fan. The engine finally compressor stalled and blew him out. He wasn't hurt except for scrapes on his hands and knees, and his parka had a friction burn on it from the round nose spinner. (Plus it scared the crap out of him) The outcome would have been different now as they have gone to conical spinners that are very sharp and pointed on those engines. The other problem would be a mechanical difficulty with the inlet stators or bleed valves. These are normally scheduled by the fuel control, or now, more commonly, the engine computer. Jet engines don't know or care if they are flying, or if they are straight and level or maneuvering. They simply suck in air, add fuel, and burn it. If an engine compressor stalls, there is a major problem with it, and it doesn't have anything to do with maneuvering. Engineers do a lot of designing and research to make sure that once the air passes the inlet, it is ready for the engine to use. I have never heard of an engine compressor stalling from flight maneuvers. It usually happens on the ground while the engine is being run-up for troubleshooting for engine messages. If an engine does compressor stall in flight, the crew usually lands and turns it over to maintenance to see what is going on. They can range from a mild "CHUFF" to a explosion-like sound that brings people out of hangars to see what is going on. They definitely get your attention!

Answer 5

This Site Might Help You.



RE:

What is a compressor stall in a jet engine?

In English please. Act like I know nothing about a jet engine because I do not. Thanks.

Answer 6

Compressor Stall is the partial breakdown of airflow within the engine due to aerodynamic stall of the compressor blades. Compressor blades are just airfoils whose angle of attack with the incoming air is adjusted so that it will be the vector sum of air velocity (passing through the engine ) and the rotational speed of the compressor. Whenever an imbalance occur between these two figures compressor stall occurs.

This will slow downs the airflow or stagnate or may cause the reverse flow in severe condition. This will reduce the engine thrust and accompanied with flame from engine inlet and outlet.

Causes of Compressor Stall : FOD, Compressor bleed valve inoperative etc..

Answer 7

When the compressor blades cannot process the amount of air coming from the engine inlet (and the stator vanes as well) the compressor of turbine engines "stall" - this translates generally by a very noisy explosion outside of the airplane and a flame that scares everyone around the aircraft -



The blades of compressors are airfoils... and every airfoil can be stalled, that is, when the angle of attack of the incoming air is too steep to be handled by the compressor - To prevent compressor stalls, engines have "variable inlet guide vanes" to direct the incoming air at a "better angle" - as well as "variable stator vanes" (as it is found in compressors of the JT9D engine) - Another way to prevent compressor stall is to use "bleed air exhaust valves" to reduce the excessive pressure in compressors -



All the gismos I mentioned above (variable inlet guide vanes, variable stator vanes, and bleed air valves) are controlled by the "variable geometry system" which is controlled by the FCU - fuel control unit - which directly reacts to the thrust lever (throttle) position -



My trick in the 747 to prevent compressor stall (when reducing power from cruise to idle for descent) was to activate "wing and engine anti-ice" and bleeding the compressor in when reducing the power to idle - when doing so, you are simply opening more bleed valves -



The "trick" works with all jet engines, should you problems with your engines -