Does Edge Tone Work with a Large Air Source?

[JaredJHuffman]

Could the principle of Edge Tone used to create a frequency in the airflow of a musical instrument such as the recorder be used to impart a frequency on a much larger air stream? Ideally I would use it in something in the range of a 24" diameter fan with around 130 mph velocity and approximately 1000 cfm. My goal would be around 85 Hz.

I'm a machine design engineer and am new to the airflow side of things, so please be patient with me. Here's my best understanding:

The easiest way to visualize this is to consider the mouthpiece of a recorder. Air is moved at a constant speed through a slit. An edge splits the airstream which generates eddy currents in a certain frequency on both sides of the edge at 180 degrees offset from each other. Either increasing the air speed or moving the edge closer to the slit will increase the frequency. Here's one explanation (http://hyperphysics.phy-astr.gsu.edu/hbase/music/edge3.html#c2"). It works differently inside of a pipe than without one (nodes can be created by opening or closing the holes), but the principle of how the original frequency is generated is the same.

Here are a couple videos showing the http://www.cfd.tu-berlin.de/%7Epanek/cfd/EdgeTone04.mpg" . Does this effect require a slit as the source, or would it work with an edge over a round airstream?
What is the effect of the edge on the velocity of the airflow?
How does the thickness of the edge effect the direction and frequency of the stream?
Would this work on a large scale as discussed in my introduction?Thanks so much for the help!

-Jared J Huffman

 

[JaredJHuffman]

I devised a simple test to get some clues about this theory. I ran a 1" x 12" air stream at fairly high velocity (100mph or so) with a 1/8" plate ground down to a knife edge and held the knife edge in front of the airstream with the plate parallel to the direction of the air flow. It did generate an audible tone, and the tone was directly related to the distance between the slit and the edge. I did not test different velocities, but I assume a lower velocity would lower the pitch.

I suspect that a 1/8" plate in a 1" air stream is only generating a tone with the middle portion of the stream while the rest of the air blows past unaffected. Does that coincide with the theory? Would a 1" or 2" thick plate be a more appropriate knife edge to generate the tone?