Q:

Pitch range and size of wind instrument

Looking at wind instruments, there is an apparent relation between the size of the instrument and the pitches it can produce; The larger it is, the lower pitches it produces. 
The question I have is, is it, without changing the type of material used, possible to change the range of a wind instrument by just changing its shape? (i.e. without changing its volume)

A:

Yes. The simplest change one could make to change the range is to modify the end condition. A pipe based instrument with an air reed has an open end at the air reed. The other end could be either open or closed. If that end is closed, the range goes down an octave, and the overtones change (so the tone, or timbre, changes, too).
Also, changing from a cylindrical shape to a conical or flared shape will change the range. Here is some info for a tube from a table in Rossing's The Science of Sound.
$$\matrix{\text{Mode} & \text{Cylindrical} & \text{Conical} & \text{Flared} \\
1 & 136.4~ \text{Hz} & 255.6~ \text{Hz} & 281~\text{Hz} \\
2 & 409.2 & 512 & 520 \\
3 & 682.0 & 771.0 & 767 \\
4 & 954.9 & 1032.0 & 1021}$$
The reason for the change is that the pressure nodes in the conical and flared tubes are non-linearly distributed.

