Re: Singing pipes

[bennett@Oakland.edu (Clarence Bennett)]

> Hello everyone,
>
> I have enjoyed the lively discussion on singing pipes, or Rijke tubes.
> The explanations seem plausible, but without a close reading, how can we
> account for the fact that the pipes do *not* sing when held over a burner
> to excite them?
>
> Jon Secaur
> Roosevelt HS
> Kent, OH

To drive a resonance, one must add energy when and where the
energy is already increasing.   For a pendulum, you push in the 
direction of motion.
    Similarly for an acoustic resonance you increase the air pressure
when and where the pressure is increasing.
For the carpet tube, the pressure in the center increases at the time
when air is rushing in at the bottom.
Yhat is exactly when the hot wires are heating the incoming air.

If the heat source were near the top, it would heat the outgoing air
and that would not help at all.

The Bunsen burner heats constantly.

The flame of the Meeker burner seems to be disturbed by the rushing air,
and so its heat output must vary with the phase of the roar.


Clarence