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.

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.

For large values of the magnetic gap, convection prevails before the conduction and little radiation surfaces because there has viscous dissipation of fluid in the magnetic gap.

5 shows the evolution of temperature for different values of the magnetic gap. The profile is linear from along the smooth pipe for all values of the magnetic gap.

By increasing both variables, the speed of rotation of the rotor and the value of the magnetic gap, we obtain an increase in the heat transfer in the range of 5%.

For the value of the magnetic gap equal to 6 mm and beyond the latter, the temperature profiles become non linear for high speeds of rotation.