Modern Approaches for the Thermal Design of High Rotational Speed, AirCooled Hydro Motor-Generators

The thermal performance of the rotor excitation winding was investigated for two high rotational speed, air-cooled salient pole synchronous motor-generators with different cooling and ventilation system designs. The two designs differ in the flow orientation of the cooling air close to the excitation winding, one with a radial and one with an axial flow direction relative to the machine’s rotational axis. Detailed 3D conjugate heat transfer (CHT) simulations were conducted to investigate the cooling efficiency of the rotor pole excitation winding. For both investigated motor-generator designs, the applied simulation approach is presented in this paper, including different calculation strategies, e.g. in terms of temporal and turbulence modeling. The obtained results were evaluated with a…