Gas Turbine Variable Stator Vane Shock Load Absorption

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Solution Overview

Problem

Gas turbine engines experience damage from shock loads during surge conditions, which cause rotational vibration in variable stator vanes due to reversed airflow, leading to potential damage in the stator vane positioning system.

Innovation Solution

A load absorption arrangement with a release mechanism that transitions from transmitting loads to absorbing them by using a fluid containment housing, a valve, and resilient members to manage fluid displacement and positioning, allowing the system to absorb shock loads above a predetermined level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the variable stator vane positioning system is designed to be rigid for precise control, then positioning accuracy is improved, but vulnerability to shock load damage increases

Engineering Contradiction:

Improvevane positioning accuracyVSAvoidsystem resistance to shock load damage

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The positioning system incorporates a release means that can dynamically transition between a locked state (for precise positioning) and an unlocked state (for shock load absorption). This allows the system to be rigid when needed but flexible when subjected to surge conditions, resolving the contradiction between positioning accuracy and shock load resistance.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system includes a fluid containment housing with resilient means (such as springs) that are pre-positioned to absorb shock loads before they can damage the positioning system components. This beforehand cushioning protects the rigid positioning components from sudden shock loads during surge conditions.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If the positioning system components are made robust to withstand shock loads, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvecomponent resistance to shock loadVSAvoidpositioning system structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The shock load absorption function is extracted as a separate subsystem (fluid containment housing with resilient means) distinct from the main positioning mechanism. This allows the positioning system to remain relatively simple while incorporating robust shock protection through the dedicated release means and fluid containment system.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The release means acts as an intermediary between the shock load and the positioning system components. It provides a controlled failure mode that protects the critical positioning components from direct shock load exposure, maintaining reliability without requiring all components to be robust.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Force

If the release means allows fluid displacement for load absorption, then shock load absorption capability is improved, but positioning precision may deteriorate

Engineering Contradiction:

Improveshock load absorption capabilityVSAvoidvane position control accuracy

Core Design Contradiction:

ForceVSMeasurement precision

Solution Approach 1:

The release means dynamically transitions between locked and unlocked states based on load conditions. During normal operation, it maintains a locked state for precise positioning. During surge conditions, it unlocks to allow fluid displacement and shock absorption, then relocks to restore positioning precision.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The resilient means in the fluid containment housing are pre-positioned to engage only during shock load events. This allows the system to maintain precise positioning during normal operation while having shock absorption capability activated beforehand but not interfering with routine positioning accuracy.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

The load absorption arrangement effectively reduces the transmission of shock loads to the stator vane positioning system, minimizing the risk of damage during surge conditions by allowing the system to absorb loads above a predetermined level, thereby protecting the components.

Implementation Method 1

The resilient means may include a resilient member which may be located within the first fluid containment compartment and may be operable between the fluid containment housing and the fluid displacement member to bias the fluid displacement member in first direction

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The fluid may be an incompressible fluid. The release means may comprise a fluid displacement member for displacing the fluid. The fluid displacement member may divide the fluid containment housing into first and second fluid containment compartments

Methodology Applied

Scientific EffectPascal's Law: Pascal's Law

Data Source

PatentUS7717669B2Load absorption arrangements for gas turbine engines

Publication Date: 2010.05.18 ROLLS ROYCE PLC

AI summary

A load absorption arrangement 40 for absorbing loads in a variable stator vane positioning system of a gas turbine engine includes a valve 42 which has a first operating condition to enable the load absorption arrangement 40 to transmit load, and a second operating condition, which is operable above a predetermined load, in which the valve 42 can release to enable the load absorption arrangement 40 to absorb the load thereon. The arrangement 40 is particularly suitable for absorbing shock loads which may arise under engine surge.