Numerical analysis of convective cooling in hydro generators

Abstract

With the high demand for electricity for the rapid development of industry and civilian usage over the last decades, there is a need to produce additional power in the energy supply market. Within this context, increasing the power output of the currently-operating generators is considered as a potential solution. However, it is not permitted to push the existing generators to operate at a higher power without a precise assessment of the impact of this increase to the integrity of the machines. One of the goals of Hydro-Québec is to develop new techniques to identify the units capacity and potential for uprating. Apart from the electro-magnetics and structural aspects, the understanding of the thermal performance of the hydro-generator is an important point that needs to be considered in order to accomplish this goal. Although the thermal analysis that employs the traditional approaches, such as the lumped-parameter thermal network combined with the convective correlations, has been successfully applied in the literature, these contain many drawbacks. A more elaborate methodology has to be performed in which the ventilation flow and the heat transfer have to be taken into account with high resolution and fidelity. An experimental approach is expensive and is limited in its application several locations in the machine. This thesis focuses on characterizing the ventilation flow and thermal features of a large hydro-generator scale model. The investigation was carried out using the computational fluid dynamics (CFD) simulations with different Reynolds-averaged Navier-Stokes turbulence models. The numerical simulations were performed on a full scale model that was designed and built at Institute de recherche d’Hydro-Québec. Initially, the mathematical formulation, including the fluid dynamics and solid heat conduction governing equations, was presented. Secondly, a review of the literature regarding the computational fluid dynamics application for the ventilation flow and thermal analysis of hydro-generators over the last 20 years was investigated. The results of numerical simulations on different numerical models and simplified models were presented in the next three chapters, in which the numerical results were validated by comparing with the available experimental data. For a certain set of appropriate numerical settings, a good agreement between the CFD predicted results and the experimental data was obtained.

Date	30 Nov 2018
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Tan Pham (Supervisor) & Paul Labbé (Co-supervisor)