Turbomachine Rotor Balancing Flange Stress Decoupling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing turbomachine rotor balancing systems face reduced service life and risk of damage due to high tangential and axial stresses at the radial summit of the annular balancing flange, primarily caused by centrifugal and thermal effects combined with clamping forces.

Innovation Solution

The design incorporates recesses on both faces of the annular balancing flange, positioned around the through-passageways near the radial summit, to decouple axial stresses from the high-tangential-stress zone by allowing the screw/nut assembly to apply pressure away from the summit, thereby reducing axial stress on the flange.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the screw/nut assembly applies clamping force directly at the radial summit of the through-passageway, then the balance weight is securely fixed to the balancing flange, but the axial stress combines with high tangential stress to reduce service life and increase damage risk

Engineering Contradiction:

Improveservice life of balancing flangeVSAvoidaxial stress at radial summit

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The patent applies local quality by creating recesses specifically at the radial summit zones of the through-passageways, where the material geometry is locally modified to change stress distribution characteristics. This localized structural modification allows the flange to better withstand the combined axial and tangential stresses without requiring global design changes.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The recesses act as pre-designed stress relief features that cushion the concentration of axial stresses before they can combine with tangential stresses at the critical radial summit locations. By providing this stress-distributing geometry in advance, the design prevents the harmful stress combination from developing to dangerous levels.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Ease of operation

If through-passageways are provided at the radial summit of the balancing flange, then balance weights can be easily mounted and adjusted, but the radial summit becomes a stress concentration zone under combined axial and tangential loading

Engineering Contradiction:

Improvemounting of balance weightsVSAvoidstrength at radial summit

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The through-passageways are provided with localized recesses at their radial summits, creating different geometric properties in different zones. The main body of the passageway remains open for weight mounting, while the radial summit zone has modified geometry to reduce stress concentration, thus combining ease of operation with improved strength.

Inventive Principle:

Principle #3Local quality

3Volume of moving object

If the balancing flange is designed with a compact structure, then the overall size is reduced, but the stress concentration at the radial summit of through-passageways increases

Engineering Contradiction:

Improvesize of balancing flangeVSAvoidtangential stress at radial summit

Core Design Contradiction:

Volume of moving objectVSStress or pressure

Solution Approach 1:

Rather than increasing the overall flange size, the patent uses local geometric modifications (recesses) at critical stress zones to manage stress concentrations. This allows the compact overall design to be maintained while locally addressing the stress concentration issue at the radial summits.

Inventive Principle:

Principle #3Local quality

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 decoupling of stresses significantly increases the service life of the balancing flanges and minimizes the risk of damage by redistributing axial loads away from the high-tangential-stress areas.

Implementation Method 1

the screw head pressing against a first face of the annular balancing flange and the balance weight pressing against a second face of the annular balancing flange

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

the highest tangential stresses were located at the radial summit of each through-passageway... the tangential stresses are essentially linked to the centrifugal or thermal effects

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 3

the tangential stresses are essentially linked to the centrifugal or thermal effects

Methodology Applied

Scientific EffectThermal effects: Thermal Expansion

Data Source

PatentUS8025483B2Balancing system for turbomachine rotor

Publication Date: 2011.09.27 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A turbomachine rotor balancing system including a balancing flange provided with through-passageways, and balance weights mounted fixedly on the balancing flange by at least one screw/nut assembly passing through one of the passageways is disclosed. For each of the passageways, the flange has on its first face a first recess passing via the radial summit of the passageway. This first recess being deprived of contact with the screw head pressing on this first face. The flange has on its second face a second recess passing via the radial summit. The second recess being deprived of contact with the balance weight pressing on this second face.