Stator and rotor vent modelling in a MVA rated synchronous machine

Abstract

-An investigation into the solution dependence of a conjugate heat transfer computational fluid dynamics (CFD) model of a synchronous generator, with respect to meshing, has been carried out. Utilising CFD as a tool for investigating the airflow and thermal performance of electrical machines is increasing. Meshing is a vital part of the CFD process, but its importance is often misunderstood or overlooked in the context of electrical machine analyses; partly due to the relative mesh independency of the finite element analysis (FEA) numerical method. This paper demonstrates how a relatively complex, aircooled generator CFD model can be considerably influenced by changes in the mesh. Flow rate, velocity and windage effects are assessed as a function of the mesh adopted. Mesh changes have been shown to affect the mass flow rate through a single vent by up to 55% and the associated heat transfer coefficient by 128%.

CFD optimisation of the thermal design for a vented electrical machine

“…Conduction alone is not sufficient to remove the heat generated in its centre. The addition of vents results in complex airflow and heat transfer which cannot be predicted adequately with analytical methods such as flow and thermal resistance networks [4].…”

“…Meshing of the stator vent and airgap were particularly challenging. They require special attention due to their high influence on the flow solution [4].…”

Thermal and Electromagnetic Stator Vent Design Optimisation for Synchronous Generators

“…Classical, salient-pole synchronous generators (SGs) [3], usually employ a cooling system that performs heat removal from the machine windings, through the use of forced air convection. Due to the physical size and geometrical complexity of such machines, there is usually an extended thermal path from the winding hotspot to the cooling surfaces [4]. For this reason, the main type of heat management for such SGs, especially for higher values of power rating, comprise radial vents.…”