Klarinet Archive - Posting 000883.txt from 2003/03

From: "Mark Charette" <charette@-----.org>
Subj: RE: [kl] Introduction
Date: Sat, 22 Mar 2003 14:34:54 -0500

> -----Original Message-----
> From: Dan Leeson [mailto:leeson0@-----.net]
>
> Aren't both cases a cylindrical instrument with one closed end?

First - I haven't done the experiment (and don't have the right size cork or
an oboe reed handy - all my corks are wine-bottle-size in diameter and most
still have wax sealing them ..), so the next paragraph is supposition only.

Second - If the diameters of the reed section and the tube section are
radically different, the instrument may acoustically behave as a conical
rather than cylindrical pipe. I have seen this effect when measuring
resonances of high CFM air flow systems (back when I was trying to keep
submarines from identifying surface ships by covering their hulls with
bubbles ... the now declassified PRAIRIE/Masker system). The flow measuring
orifices set up standing waves, and they changed resonances in the tubing
from 3rd to 2nd harmonics at a particular flow rate (acting as if the piping
changed from a cylindrical to conical shape). The flow region in the
downstram piping became critically unstable during this phase, too - 27000
CFM of air can as as damaging as water hammer.

mark C.

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