Aerospace Interrupted air flow at fan inlet, resulting in fan stall

I'm looking for an on-line paper/article/pdf about ducted fans; "Interrupted air flow at fan inlet (subsonic), resulting in fan stall" which I can print out and read. Centrifugal, axial and or mixed-flow fans included.

I have not had much luck doing a Google search on my own, perhaps I'm using the wrong search terms.

I'm interested in non-bell shape inlets, something "S" shaped, or with a louvered grille up ahead of the fan. I'm assuming inlet plenum volume, drag and shape also come into play.

I see inlets (on cars, airplanes, helicopters) for circulation, cooling air and auxiliary power generation which are not like those used for thrust (which are tube/foil-like). I also see on hovercraft, lift fans at right angle of flow, but thrust fans in-line with direction of motion. Is there an efficiency ratio here, what's the design threshold?

I just want to learn a little (get me to fist base so I don't sound so stupid), and maybe it will help put me to sleep at night too.:wink:

EDIT: something with pictures would be nice.
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Science Advisor
Inlet distortion is a very prominent field/specialization of study in aerospace and propulsion. I can't imaging a one page paper giving you everything you need to know about the topic. Do you have a specific paper in mind? We do all sorts of real world distortion testing on our fans and compressors to ensure operability and performace for various inlet configurations and inlet flow patterns. I am highly doubtful that this is going to be as easy as you think.

You might want to look at NASA's document server: [Broken]
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Thanks for the link.

I want to get the fundamentals right, then slowly move on to specific situations and see what makes them work or fail.

Something general at a high school level would be fine. If a professional level paper, I'll read it a few times and maybe 20% will soak in.

I took college calculus (up to 4) with engineering students 20 years ago, but being an architect I've displaced that temporary memory long ago.:wink:

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