Rotor Disc Relief Channels Prevent Spindle Bolt Fracture

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Spindle bolts in gas turbine engines are prone to fracture due to fretting fatigue and water and debris accumulation, leading to premature failure.

Innovation Solution

A rotor disc with radially extending relief channels, or scallops, that remove condensation and debris from the spindle bolt area, preventing air ingress and utilizing a curved design with nozzles to enhance debris and water removal, thereby reducing the risk of spindle bolt fracture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional spindle bolt holes are used without relief channels, then the structure is simple and manufacturing is easy, but condensation and debris accumulate behind the bolt leading to fretting fatigue and fracture

Engineering Contradiction:

Improvespindle bolt fracture resistanceVSAvoidrotor disc structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The spindle bolt hole is segmented by adding relief channels that divide the hole into separate regions. These channels create distinct zones for condensation/debris accumulation and dry bolt contact, preventing harmful material buildup while maintaining structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Harmful condensation and debris are extracted from the confined space behind the spindle bolt through relief channels. These channels provide escape pathways that remove accumulated materials, eliminating the root cause of fretting fatigue and bolt fracture.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If relief channels are added to remove condensation and debris, then spindle bolt reliability improves, but manufacturing complexity and machining time increase

Engineering Contradiction:

Improvespindle bolt service lifeVSAvoidrotor disc machining difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Relief channels are designed with curved, scalloped geometries rather than straight linear paths. These curved channels follow the stress flow patterns and provide more effective debris removal while being amenable to standard machining operations, balancing manufacturing feasibility with functional effectiveness.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If air is allowed to ingress through relief channels, then condensation removal is enhanced, but debris may be blown back onto the spindle bolt surface accelerating fretting fatigue

Engineering Contradiction:

Improvecondensation removal efficiencyVSAvoiddebris blowback onto bolt

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Relief channels are positioned asymmetrically at specific angular locations (e.g., 45 degrees) relative to the spindle bolt axis rather than symmetrically. This asymmetric positioning creates unidirectional airflow patterns that draw condensation away from the bolt while preventing debris blowback onto the critical bolt surfaces.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

Different regions of the relief channel system are designed with different characteristics - some channels are optimized for air intake while others are positioned to serve as exhaust paths. This local differentiation ensures that air flow removes condensation effectively without creating harmful debris deposition zones on the bolt.

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

The rotor disc design effectively reduces the likelihood of spindle bolt fractures by removing condensation and debris through centrifugal forces, preventing blowback and enhancing water escape, thus extending the lifespan of spindle bolts in gas turbine engines.

Implementation Method 1

As the rotor discs spins, centrifugal forces cause the condensation to be forced outwardly into the circumferential groove, where the condensation and debris flow into the relief channels and are exhausted out of the rotor disc body through the outer opening.

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

The relief channel may have a decreasing cross-sectional area moving radially outward... The relief channel may foster removal of condensation and debris from the space between the spindle bolt and the surface forming the spindle bolt hole

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS9951621B2Rotor disc with fluid removal channels to enhance life of spindle bolt

Publication Date: 2018.04.24 SIEMENS ENERGY GLOBAL GMBH & CO KG

AI summary

A rotor disc configured to reduce the likelihood of fractures developing in spindle bolts in gas turbine engines is disclosed. The spindle bolts extend axially through the rotor disc to retain the rotor assembly in place in the gas turbine engine. The rotor disc may be formed from a rotor disc body having a plurality of circumferentially positioned spindle bolt holes sized to house a spindle bolts within each spindle bolt hole. One or more relief channels, which also may be referred to as scallops, may extend radially outward from one of the spindle bolt holes. The relief channels may foster removal of condensation and debris from the space between the spindle bolt and the surface forming the spindle bolt hole and may be configured to discourage the ingress of air through the relief channel and into space between the spindle bolt and the surface forming the spindle bolt hole.