Experimental and numerical investigation of the cooling air flow in an electric generator

Abstract

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.

The cooling air flow in a small-scale electric generator has been investigated experimentally and numerically, and the results have been compared to each other. The studies have been made in cold conditions, without heat transfer. The velocity profiles at the inlet of the generator have been measured by means of a 5-hole probe, traversed in the axial direction to give the axial distribution of the radial velocities at the inlet of the generator. The outlet velocity distribution has been measured by means of a total-pressure rake, consisting of a number of total pressure probes, which gives the horizontal distribution of the velocity magnitudes, aligned with the stator channels at the outlet of the generator. Smoke visualization of the flow has been performed at the inlet of the generator and the flow pattern has been visualized. The numerical study has been performed using the OpenFOAM open source CFD software. The corresponding numerical velocity profiles at the inlet and the outlet of the generator have been extracted and compared with the experimental profiles. The velocity vectors at the inlet of the generator have been compared to the flow pattern obtained by the smoke visualization. Because of geometrical dissimilarities between the experimental rig and the numerical computational domain, there are unavoidable differences in the results. This yields a qualitative comparison, although the comparisons still show a relatively good quantitative agreement between the experiments and the numerical simulations.