Intercooled Turbine Cooling Air With Dual Towershaft Gearbox

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Gas turbine engines face cooling challenges due to high temperatures and pressures in the turbine section, where utilizing fully compressed air is inefficient, and existing cooling methods are not optimally effective in managing these conditions.

Innovation Solution

A gas turbine engine assembly with a two-spool configuration, including a first and second turbine shaft, towershafts, and an accessory drive gearbox with a transmission that allows the starter generator assembly to operate at different speeds, coupled with a boost compressor and heat exchanger system to efficiently cool the turbine section using air tapped upstream from the compressor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If cooling air is tapped from downstream end of compressor section, then cooling air pressure is sufficient to move into turbine section, but air which has already been fully compressed is utilized inefficiently

Engineering Contradiction:

Improvecooling air pressureVSAvoidenergy efficiency

Core Design Contradiction:

Stress or pressureVSLoss of energy

Solution Approach 1:

The patent extracts cooling air from an upstream location in the compressor section (before full compression) rather than taking it from the downstream end. This extracted air is then pressurized by a dedicated boost compressor to achieve the required pressure for turbine cooling, thereby avoiding the waste of using air that has already been fully compressed for the core engine functions.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the air supply system into two separate paths: one for core engine compression and another dedicated path for cooling air supply. The cooling air path includes its own boost compressor that pressurizes air extracted from upstream, separating the cooling function from the main compression function to optimize overall efficiency.

Inventive Principle:

Principle #1Segmentation

2Productivity

If engine core size is reduced to increase compressor exit pressures and temperatures, then turbine temperatures increase, but cooling challenges are raised

Engineering Contradiction:

Improvecompressor exit pressureVSAvoidturbine temperature

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent introduces a boost compressor as an intermediary device in the cooling air supply path. This boost compressor acts as a mediator that takes air from upstream (where pressure is lower) and pressurizes it to the required level for turbine cooling, enabling the system to handle higher turbine temperatures resulting from reduced core size while maintaining effective cooling capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If starter generator assembly is driven at variable speeds through transmission, then engine operability is improved, but device complexity increases

Engineering Contradiction:

Improvestarter generator speed rangeVSAvoidtransmission system complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a transmission system that provides multiple gear ratios, allowing the starter generator assembly to operate at different speeds for different engine conditions. This multi-functional transmission enables the single starter generator to serve multiple purposes: starting the engine, acting as an APU, and providing power during flight, thereby improving adaptability without requiring multiple separate devices.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 configuration enhances the efficiency of air usage, reduces fuel burn, and improves engine performance by allowing the starter generator assembly to operate within a narrower speed range, thereby improving engine operability and reducing exhaust gas temperatures.

Implementation Method 1

passed through a boost compressor and heat exchanger, and then passed to a turbine section to cool the turbine section

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

This air is then passed through a boost compressor, which increases its pressure such that it now can move into the turbine section

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS11846237B2Gas turbine engine with intercooled cooling air and dual towershaft accessory gearbox

Publication Date: 2023.12.19 RTX CORP

AI summary

An exemplary gas turbine engine assembly includes a fan section including a fan, a first spool having a first turbine operatively mounted to a first turbine shaft, and a second spool having a second turbine operatively mounted to a second turbine shaft. The first and second towershafts are respectively coupled to the first and second turbine shafts. An accessory drive gearbox includes a set of gears. A compressor is driven by the first towershaft. A transmission couples a starter generator assembly to the set of gears. The transmission is transitionable between a first mode where the starter generator assembly is driven at a first speed relative to the second towershaft in response to rotation of the second towershaft, and a second mode where the starter generator assembly is driven at a different, second speed relative to the second towershaft in response to rotation of the second towershaft.