Computational fluid dynamics modelling of an entire synchronous generator for improved thermal management

Abstract

This paper is the first in a series dedicated to investigating the airflow and thermal management of electrical machines. Due to the temperature dependent resistive losses in the machine"s windings, any improvement in cooling provides a direct reduction in losses and an increase in efficiency. This paper focuses on the airflow which is intrinsically linked to the thermal behaviour of the machine as well as the windage power consumed to drive the air through the machine. A full CFD model has been used to analyse the airflow around all major components of the machine. Results have been experimentally validated and investigated. At synchronous speed the experimentally tested mass flow rate and windage torque were under predicted by 4% and 7% respectively by the CFD. A break-down of torque by component shows that the fan consumes approximately 87% of the windage torque.

Improved Damper Cage Design for Salient-Pole Synchronous Generators

“…In [7] an innovative numerical integration method is proposed and also compared with the traditional dq-axis approach with very positive results. Although the worth of these traditional techniques is well known and consolidated, with the recent advancements in computational capabilities, a significant shift towards numerical methods, such as finite-element (FE) and computational fluid dynamics [12], [13], allows for improved accuracy and extra degrees of freedom in the design process. Due to this, today there is an increasing interest in the damper winding designs (and SGs in general [14]), as this can be very beneficial to the overall SG performance.…”

Damper cage loss reduction and no-load voltage THD improvements in salient-pole synchronous generators

“…The worth of these traditional techniques is well known and their longevity has been consolidated by their use over many decades. However, with the recent advancements in computational capabilities, a significant shift towards numerical methods, such us finiteelement (FE) and computational fluid dynamics [10,11], is slowly taking place. Such methods offer an increased accuracy and extra degrees of freedom in the design process.…”

Stator and rotor vent modelling in a MVA rated synchronous machine

“…This is due to the mesh's influence on the solution. Narrow passageways in electrical machine rotor-stator airgaps often draw attention due to their complex shape for solving fluid flow, where blended boundary layers may exist and a significant proportion of the heat transfer from components to cooling fluid occurs [4,16]. For a model with a large number of narrow rotor and stator vents the meshing of these regions is similarly complex and requires detailed meshing attention.…”

“…Vents are particularly effective for cooling machines with long core lengths, as they may be used to target hotspots, which are otherwise difficult to remove with a non-vented cooling arrangement. Improved airflow and thermal analysis directly increases machine efficiency [3,4]. However, the design of venting an electrical machine core is not straightforward, as they displace active material, re-distribute flow and contribute to additional windage losses.…”