VENTILATION AIR FLOW FIELD CHARACTERISTICS IN A HYDRO GENERATOR Model

Paper in proceeding, 2016

Knowledge of the ventilation flow field characteristics in electric generators is crucial for both designing new generators and refurbishing old ones. Such knowledge is achievable by in-depth investigations of the aerodynamics in these machines. In this article the velocity and pressure fields inside a generator model are analysed both experimentally and numerically. The experimentally measured total pressure and velocity distributions are presented. PIV is applied to reveal the details of the flow inside the stator channels. Steady-state CFD simulations are performed, based on the multiple rotating reference frames method. The rotor-stator coupling is handled by both the frozen rotor and mixing plane approaches. The numerical results are validated with the time-averaged experimental data. Both rotor-stator approaches capture the time-averaged properties well, within their limitations. It is found from the experimentally validated numerical results that the value of the axial and tangential velocity components in the air gap determines how uniform the flow distribution becomes inside the stator channels.