Gear-Driven Variable Vanes for Gas Turbine Thermal Growth

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Solution Overview

Problem

Conventional gas turbine engines with variable stator vanes face challenges in efficiently adjusting the angle of attack due to mechanical complexities and thermal growth, leading to thrust loads and radial binding issues.

Innovation Solution

A gear-driven variable vane system is introduced, featuring a ring gear assembly mounted within the engine casing and vane modules with gears that engage the ring gear assembly, allowing for precise positioning of vane airfoils through a motor-driven mechanism, which reduces thrust loads and accommodates thermal growth by allowing radial motion and self-centering of the ring gears.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional variable stator vanes with spindles and lever arms are used, then the vanes can be adjusted, but the mechanical complexity increases and thermal growth causes radial binding

Engineering Contradiction:

Improvevane angle adjustmentVSAvoidmechanical complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the gear mechanism from the conventional spindle and lever arm configuration. Instead of using spindles that extend radially through the engine casing, the invention uses a ring gear assembly with gear-driven vane modules, eliminating the complex lever arm mechanism while maintaining variable vane capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a dynamic radial motion capability to the ring gear assembly, allowing it to move radially to accommodate thermal growth. This dynamic adjustment capability resolves the radial binding issue while maintaining the variable vane function

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If conventional variable stator vanes are used, then vane positioning is achieved, but thrust loads increase

Engineering Contradiction:

Improvevane positioning precisionVSAvoidthrust loads

Core Design Contradiction:

Manufacturing precisionVSForce

Solution Approach 1:

The patent segments the vane positioning function into independent vane modules, each with its own gear mechanism. This segmentation allows each module to be positioned independently, improving precision while distributing the thrust loads across multiple smaller units rather than concentrating them in a single complex mechanism

Inventive Principle:

Principle #1Segmentation

3Device complexity

If radial motion is restricted in conventional designs, then structural simplicity is maintained, but thermal growth causes binding

Engineering Contradiction:

Improvestructural simplicityVSAvoidthermal growth accommodation

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent introduces dynamic radial motion capability to the ring gear assembly, allowing it to expand and contract radially to accommodate thermal growth. This dynamic adjustment resolves the binding issue caused by thermal expansion while maintaining operational reliability

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8240983B2Gas turbine engine systems involving gear-driven variable vanes

Publication Date: 2012.08.14 RTX CORP

AI summary

Gas turbine engine systems involving gear-driven variable vanes are provided. In this regard, a representative gas turbine engine system includes: a ring gear assembly operative to be mounted within an engine casing; and a vane module having a first vane airfoil and a first gear, the first gear being operative to engage the ring gear assembly such that movement of the ring gear alters a position of the first vane airfoil.