Compressive Axial Preload Validation for Gas Turbine Rotors

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Solution Overview

Problem

In gas turbine engines, applying a compressive axial preload to rotatable elements around a shaft is challenging due to defects like improper seating, deviations in squareness, and friction locks, which can lead to ineffective preload application despite elongation of tensioning rods.

Innovation Solution

A method involving progressively increasing axial tension to a tensioning member, monitoring load and elongation, determining validation parameters, and comparing them to predetermined ranges to correct the preload, ensuring effective compressive axial preload application through a system with sensors and processing units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If tensioning rods are elongated to apply compressive preload, then the preload force is increased, but defects such as improper seating, friction locks, and deviations in squareness may occur causing ineffective preload application

Engineering Contradiction:

Improvecompressive preload forceVSAvoideffectiveness of preload application

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The patent applies preliminary action by monitoring load and elongation parameters during the preload application process to detect defects early. Validation parameters are determined and compared against predetermined ranges before the preload is finalized, allowing correction of issues like improper seating or friction locks while the assembly is still being preloaded, rather than discovering them after completion

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by continuously monitoring the load in tensioning members and elongation of the tensioning member during preload application. This real-time feedback allows the system to detect when validation parameters fall outside acceptable ranges and trigger corrective actions, ensuring reliable preload application despite the complexity of the assembly process

Inventive Principle:

Principle #23Feedback

2Reliability

If validation parameters are monitored and corrected during preload application, then the reliability of preload application is improved, but the complexity of the assembly process increases

Engineering Contradiction:

Improvevalidity of preload applicationVSAvoidcomplexity of preload application process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies self-service by enabling the assembly process to validate and correct itself through automated monitoring of load and elongation parameters. The system uses predetermined validation ranges and automatic detection of defects to guide the preload application, reducing the need for complex external inspection equipment or manual verification procedures

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If elements are disassembled and reassembled to correct defects, then the manufacturing precision is improved, but the production time is increased

Engineering Contradiction:

Improvesquareness and seating accuracyVSAvoidassembly cycle time

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies preliminary action by performing validation parameter monitoring and defect detection during the initial assembly and preload application process. This allows identification of issues like improper seating or deviations in squareness while the assembly is still accessible and can be easily corrected, avoiding the need for time-consuming disassembly and reassembly operations later

Inventive Principle:

Principle #10Preliminary action

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 method ensures accurate and effective compressive axial preload application, reducing vibrations, optimizing load distribution, and maintaining assembly integrity by detecting and correcting defects before assembly completion.

Implementation Method 1

the elongation of the tensioning rods is measured to determine if the load applied is sufficient

Methodology Applied

Scientific EffectElastic elongation: Elasticity

Data Source

PatentUS10048144B2Method and system for applying a compressive preload

Publication Date: 2018.08.14 PRATT & WHITNEY CANADA CORP

AI summary

A method of validating a compressive axial preload on adjacent rotatable elements serially arranged around a shaft, created through application of a progressively increasing axial tension to a tensioning member configured to compress the elements when the axial tension is applied. The method includes monitoring a load in the tensioning member and/or in one or more of the elements, and an elongation of the tensioning member, during application of the axial tension, determining at least one validation parameter from the load and the elongation, comparing each validation parameter with a respective predetermined range therefor; and if at least one of the at least one validation parameter is out of the respective predetermined range, correcting the preload on the elements, and repeating the method. A method of applying the compressive preload and a system for validating the compressive preload are also described.