  We report numerical evidences of the influence of the blades' shape and of
their direction of rotation on turbulent flows generated by counter-rotating
bladed-disks enclosed in a cylinder, known as the von K\'arm\'an swirling flow.
We show that, although the mean flows generated by stirrers with straight or
curved blades can be topologically similar, turbulence production occurs in
different zones. The structure and intensity of the turbulent fluctuating field
also varies with the geometry, and retains significant anisotropy. From the
direct numerical simulations fields, we analyse the dynamics of enstrophy and
we show that the distribution of relative helicity h depends on the forcing
mecanism of turbulence.
