These two subsets of an electric machine [1] is called an annular magnetic gap which circulates a cooling fluid.

Initially, we studied the flow of air in to the smooth air magnetic gap for different rotor speed and for different axial velocities of air.

The latter studied the stability of an incompressible viscous flow in the magnetic gap formed by coaxial cylinders of infinite length and rotation without axial flow.

Heat transfer in this space called magnetic gap is influenced by the speed of rotation of the rotor, the speed of air blowing, the temperature gradient between the stator and rotor, the surface roughness.

For this geometry fluted (corrugated rotor or stator) the Taylor number is modified taking into account the shape of the corrugated (form factor): F - geometric factor based on the work of [3]; [omega] - the speed of rotation, rd/s; e - thickness of the magnetic gap, m.

It is observed for the same axial velocity of air, the temperature evolution takes the same shape along the rotor, whatever speed and whatever the value of the magnetic gap.