Generator Stator Cooling Passages Reduce Windage Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High power density aircraft generators experience reduced operational efficiency due to uncontrolled oil flow from the back iron, which floods the rotor-stator air gap, causing significant windage losses in the internal oil management system.
Innovation Solution
The generator design incorporates cooling passages within the stator laminations and an enclosed cavity to isolate the rotor from the cooling fluid, preventing oil from entering the rotor-stator gap and enhancing cooling efficiency by using a fluid-cooled system with radial and axial channels for effective heat removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If uncontrolled oil flow is used for stator cooling, then cooling coverage is improved, but windage loss increases due to oil flooding the rotor-stator air gap
Solution Approach 1:
The stator cooling system is segmented into distinct zones: a first cooling passage for the stator body and a second cooling passage for the stator end turns. This segmentation allows controlled oil flow to specific areas without flooding the rotor-stator air gap, reducing windage loss while maintaining cooling effectiveness.
Solution Approach 2:
A back iron oil flow distribution system acts as an intermediary between the cooling oil source and the stator components. This intermediary controls and directs the oil flow through designated passages, preventing uncontrolled flooding of the air gap while ensuring adequate cooling of stator components.
2Productivity
If high power density is achieved in the generator, then productivity is improved, but operational efficiency decreases due to windage losses
Solution Approach 1:
Different regions of the stator receive different cooling arrangements: the stator body receives cooling through radial passages in the back iron, while stator end turns receive cooling through axial passages in the end shields. This localized cooling approach enables high power density design while preventing oil from entering the rotor-stator air gap, maintaining operational efficiency.
3Device complexity
If internal oil management system is used for cooling, then device complexity is reduced, but windage loss increases due to uncontrolled oil flow
Solution Approach 1:
The oil flow paths are dynamically directed through controllable passages rather than allowing free flow. The back iron and end shields incorporate designated flow paths that guide oil through the stator components and back to the reservoir, creating a controlled circulation system that reduces windage loss while maintaining simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively reduces windage losses and increases the operational efficiency of the generator by maintaining a dry rotor and optimizing cooling fluid circulation within the stator, thereby enhancing the overall performance of the high power electric machine.
Implementation Method 1
cooling passages within the stator laminations and an enclosed cavity to isolate the rotor from the cooling fluid
Implementation Method 2
fluid-cooled system with radial and axial channels for effective heat removal
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A stator (38) of an electrical generator (20) includes a stator core including a plurality of stacked stator laminations (44) and at least one end turn. At least one cooling passage (60) provides a fluid flow path through a portion of the plurality of stator laminations (44) to the at least one end turn. The at least one cooling passage (60) includes at least one radial channel (62) arranged in fluid communication with an axial channel (64). The at least one cooling passage (60) is formed directly into the portion of the plurality of stator laminations (44).