Air Bubble Flushing in Liquid Cooled Generator Cores

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Liquid cooled generators face overheating and damage due to trapped air bubbles in the cooling fluid flow paths, which existing methods struggle to efficiently flush out, affecting the cooling efficiency and reliability of the generators.

Innovation Solution

The design incorporates a rotor with a central core and stator winding where the flow line through the central core has larger diameters to allow air passage while restricting liquid flow, using orifices of specific diameters at the ends to facilitate efficient bubble flushing and maximize fluid flow through the main winding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a cooling tube (bubble flushing tube) is formed in the axis of the core lamination to flush air bubbles, then air bubbles can be removed from the cooling fluid flow path, but fluid flow through the main winding is reduced

Engineering Contradiction:
Improvebubble flushing effectivenessVSAvoidfluid flow through main winding
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The invention extracts the bubble flushing function from the main cooling flow path by providing a separate dedicated flushing tube (220) that runs through the core lamination axis. This allows air bubbles to be removed through a separate channel without diverting the main cooling fluid flow from the windings, thus maintaining both reliable bubble removal and high cooling efficiency

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The cooling system is segmented into two independent flow paths: the main cooling flow path that delivers fluid through the windings for heat removal, and a separate bubble flushing path through the core lamination. This segmentation allows each function to operate independently at optimal flow rates without compromising the other

Inventive Principle:
Principle #1Segmentation

2Reliability

If the flow line through the central core has larger diameters to allow air passage, then bubble flushing is improved, but liquid flow restriction increases

Engineering Contradiction:
Improveair bubble removalVSAvoidliquid flow through windings
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The separate flushing tube acts as an intermediary channel that handles the air bubble removal function without interfering with the main cooling fluid flow. The flushing tube provides a dedicated path for gas-liquid separation, allowing the main cooling system to maintain high liquid flow rates while bubbles are simultaneously removed through the intermediary flushing path

Inventive Principle:
Principle #24Intermediary (Mediator)

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 approach ensures effective bubble flushing and maintains high fluid flow through the main winding, reducing the risk of overheating and damage while optimizing cooling efficiency by directing more fluid flow to the main winding during operation.

Implementation Method 1

The first and second diameters are configured such that air flow is permitted to pass through the first and second laminates and to restrict the flow of a liquid through the first and second laminates

Methodology Applied
Scientific EffectGas-liquid flow separation through orifices: Two-Phase Flow

Implementation Method 2

A flow line passes through the central core and is configured to extend from the first laminate to the second laminate

Methodology Applied
Scientific EffectFluid flow through porous/structured path: Laminar Flow

Implementation Method 3

Such generators employ a cooling flow of fluid through spaces between conductors in a main field winding to prevent overheating and damage to the main field winding

Methodology Applied
Scientific EffectConvection cooling: Convection

Data Source

PatentEP3035499B1Improved methods and systems of air bubble flushing in liquid cooled generators
Publication Date: 2018.03.14 HAMILTON SUNDSTRAND CORP
  • EP3035499B1 patent drawingFigure 1A
  • EP3035499B1 patent drawingFigure 1B
  • EP3035499B1 patent drawingFigure 2

AI summary

A liquid cooled generator is provided having a rotor (104, 200, 300) having a central core (110, 210, 310) and a main stator winding (112) wrapped around the central core. A first laminate (114, 214, 314) at a first end of the central core is provided having a first orifice (120, 220, 320) defining a first diameter (230, 336) and a second laminate (116, 216, 316) at a second end of the central core is provided having a second orifice (120, 220, 320) defining a second diameter that is the same as the first diameter. A flow line (118, 218, 318) passes through the central core and is configured to extend from the first laminate to the second laminate, the flow line defining a third diameter (232, 332) that is larger than the first and second diameters. The first and second diameters are configured such that air flow is permitted to pass through the first and second laminates and to restrict the flow of a liquid through the first and second laminates.