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

Summary

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 focus on local temperature distributions and averaged rotor winding temperatures. A comparison with plant measurements that were conducted during commissioning of the investigated motor-generators showed good agreement with the presented simulation model results for both machines. In summary, the research presented in this paper conclusively shows that the proposed simulation workflows are valid approaches to investigate the given cooling and ventilation system designs for high rotational speed, air-cooled salient pole synchronous motorgenerators. Therefore, the presented simulation approaches might play a significant role in assuring safe operating life for similar future machines.

Additional informations

Authors

B. DIEBEL, A. WALTER-KRAUSE, M. ADAM, T. HILDINGER, R. JESTERZUERKER

Keywords

Electrical machine, Air-cooled hydro power motor-generator, Thermal analysis, Computational fluid dynamics, Conjugate heat transfer