Gas Turbine Rotor Disk Bleed Air Cooling

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Solution Overview

Problem

Gas turbine engines face thermal induced stress due to temperature gradients across rotor disks, which reduces their operating life as the rim and arm portions heat faster than the web portions during transient conditions.

Innovation Solution

Incorporating first and second bleed air passages through the rim portions of rotor disks, which direct heated core airflow into rotor cavities and then to the turbine section for cooling, reducing thermal gradients and stress by allowing bleed air to flow through internal cooling passages in the shaft connecting the compressor and turbine sections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If operating temperatures are increased to improve gas turbine engine efficiency, then efficiency is improved, but thermal induced stress increases reducing operating life

Engineering Contradiction:

ImproveefficiencyVSAvoidoperating life

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The rotor disk is segmented into distinct functional zones with bleed air passages creating separate flow paths through the rim and web portions, allowing differential cooling strategies for different structural components

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Bleed air serves as an intermediary cooling medium, extracted from the core flow and routed through passages in the rotor disk and shaft to remove heat from critical structural components, enabling higher operating temperatures without excessive thermal stress

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If bleed air passages are added to rotor disks to reduce thermal stress, then thermal induced stress is reduced, but device complexity increases

Engineering Contradiction:

Improvethermal stressVSAvoidstructure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The rotor disk structure performs multiple functions: it supports rotor blades, contains bleed air passages for cooling, and routes cooling air to the shaft. The shaft also contains both structural and cooling functions, consolidating multiple system requirements into unified components

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The cooling passages are integrated directly into the rotor disk and shaft structures, merging the cooling system with the structural components rather than adding separate external cooling systems, thereby reducing overall device complexity

Inventive Principle:

Principle #5Merging (Combining)

3Temperature

If turbine bleed air passage cross-sectional area is increased to enhance cooling, then cooling efficiency is improved, but air flow distribution becomes unbalanced

Engineering Contradiction:

Improvecooling efficiencyVSAvoidair flow distribution

Core Design Contradiction:

TemperatureVSQuantity of substance

Solution Approach 1:

Different passages are designed with different cross-sectional areas matched to their specific cooling requirements: larger turbine bleed air passages for high-temperature turbine cooling, and smaller rotor disk passages for localized rim and web cooling, optimizing cooling efficiency while maintaining flow balance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The cross-sectional area parameter of bleed air passages is optimized based on location and cooling demand, with the turbine passage area being larger than the sum of rotor disk passages to account for the higher thermal load in the turbine section while maintaining proper flow distribution

Inventive Principle:

Principle #35Parameter changes

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 solution effectively reduces thermal induced stress in rotor disks by managing temperature gradients and extends the operating life of gas turbine engines by efficiently cooling the turbine section using a larger cross-sectional area of turbine bleed air passages.

Implementation Method 1

Bleeding core air flow through at least one first bleed air passage that extends through a forward rim portion of the first rotor disk. Bleeding the core air flow through at least one second bleed air passage that extends through an aft rim portion of the first rotor disk.

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

heating an upstream rotor cavity forward of the first rotor disk and a downstream rotor cavity aft of the first rotor disk while bleeding the core air flow

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10954796B2Rotor bore conditioning for a gas turbine engine

Publication Date: 2021.03.23 RTX CORP

AI summary

A rotor assembly includes a plurality of rotor disks that each have a rim portion. The plurality of rotor disks includes a first rotor disk and at least one first bleed air passage that extends through a forward rim portion of the first rotor disk. At least one second bleed air passage that extends through an aft rim portion of the first rotor disk.