Abstract
The tone from a small police whistle when blown into weakly, can be listened into in such a way that the frequency is proportional to the amount of blowing. This fact hints to us some whistle element can be a new flowmeter that detects the flow by the frequency. Here we extract a structure of the whistle element that is desirable as the flowmeter. The spectrum of the whistle tone has several peaks and some frequencies with the peaks are linearly proportional to the flow and the other keeps same values. The whistle itself includes several tone generating mechanisms. This research aims at extracting an element and/or mechanism that generates the tone whose frequency is purely proportional to the flow.
First we investigate what role the each component (a) whistle itself, (b) edge and (c) cylindrical cavity plays in the tone generation. We investigated how the tone frequency changes as flow increases for each element and found the cylindrical cavity played the best role as the flowmeter in the sense of the range ability, stability and linearity.
