  We present experimental results obtained from pipe flows generated by fractal
shaped orifices or openings. We compare different fractal orifices and their
efficiencies to re-generate axi-symmetric flows and to return to the standard
flow generated by a perforated plate or a circular orifice plate. We consider
two families of fractal openings: mono-orifice and complex-orifice and
emphasize the differences between the two fractal families. For the Reynolds
number we use, we found that there is an optimum iteration for the fractal
level above which no improvement for practical application such as flowmetering
is to be expected. The main parameters we propose for the characterisation of
the fractal orifice are the connexity parameter, the symmetry angle and the gap
to the wall $\delta^*_g$. The results presented here are among the firsts for
flows forced through fractal openings and will serve as reference for future
studies and bench marks for numerical applications.
