Insane Jet Maneuvers, where do they get the mass flow?

[wesmac]

So I am doing a presentation on effects of inlet distortion on fan performance, I am trying to gauge it more towards the inlet aspect, diverting boundary layers, etc. So I am wondering, how do fighter jets pull such quick turns, and still maintain enough mass flow not to stall the compressors? I mean, i know they have variable inlets and bleed, and the like, even IGV`s, but something just doesn't make sense, you have to have uniform flow into the compressor or lots of bad things happen...right?!



Happy Thanksgiving!

 

[FredGarvin]

We spend a lot of time designing compressors to survive with non ideal inlet conditions. The performance definitely takes a hit in those instances but luckily they are short lived events.

When we do compressor testing in the cells, we purposely distort the inlet flow to examine stall margin with non-ideal inlets. Before the airframe sees an engine, that engine has seen most of its flight envelop on the ground.

 

[wesmac]

I see. Thanks for the info! Hadnt looked at it in that aspect

 

[minger]

To add to what Fred said, we can use things like distortion screens which can be tuned to the amount of expected distortion.

Also, for quantifying the amount, I'm not sure what method you're using, but we have typically used the KD2 method in the past. It's a method that I know at least the Air Force uses as well.

A quick google gave me this thesis which looks like it has a lot of good background information if you want to dive deeper.
http://dspace.mit.edu/bitstream/handle/1721.1/42186/22926364.pdf?sequence=1