Compressor Blade Flexible Tip Groove Cutting

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Gas turbine compressor blades experience damage and air leakage due to rub encounters with the surrounding case, which existing solutions like abradable coatings and cutting edges are costly and inefficient.

Innovation Solution

A compressor blade with a cap and flexible elements that become rigid at operating speeds to cut a groove in the case, reducing rub damage and air leakage by creating a more tortuous path and improving sealing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the radial gap between blade tips and case is reduced to minimize air leakage, then engine efficiency is improved, but blade tips become susceptible to rub damage due to manufacturing tolerances and thermal expansion

Engineering Contradiction:

Improveair leakageVSAvoidblade tip damage

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The flexible cutting elements are pre-installed on the blade tips before operation. During initial operation, these elements proactively cut a groove in the case inner diameter, creating a more tortuous path for air leakage before any rub damage can occur. This preliminary action prevents the need for reactive damage mitigation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention converts the potentially harmful rub encounters into a beneficial groove-cutting action. The flexible elements are designed to intentionally contact and cut the case, creating a groove that actually reduces air leakage. The harmful rubbing is transformed into a useful sealing mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If abradable coating is applied to the case to sacrificially abrade during rub, then blade tip damage is reduced, but manufacturing complexity and quality control requirements increase

Engineering Contradiction:

Improveblade tip damageVSAvoidcoating application

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The flexible cutting elements are designed as consumable components that are relatively inexpensive compared to blade tips or case coatings. They are intended to be replaced periodically, sacrificing themselves to protect the more valuable blade and case components from damage.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

Instead of making the case soft and sacrificial (abradable coating), the invention makes the blade tip elements flexible and sacrificial. The roles are inverted: the rotating blade element becomes the sacrificial component rather than the stationary case.

Inventive Principle:

Principle #13The other way round (Inversion)

3Loss of energy

If cutting edge coating is deposited on blade tip to create groove, then air leakage is reduced, but deposition thickness and cost increase

Engineering Contradiction:

Improveair leakageVSAvoidcoating deposition

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The cutting functionality is segmented from the main blade structure and implemented as separate flexible elements. These elements can be individually manufactured and then attached to the blade tip, allowing for simpler manufacturing of each component while achieving the collective function of groove cutting.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cutting elements are designed to be flexible rather than rigid, allowing them to adapt to the case surface during rotation. This flexibility enables effective groove cutting without requiring thick coatings, as the elements can conform and cut through their own thickness rather than relying on a thick deposited layer.

Inventive Principle:

Principle #15Dynamics

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 flexible elements effectively reduce blade tip damage and air leakage by creating a coaxial groove in the case, enhancing the high-cycle fatigue life and sealing efficiency of the compressor blades.

Implementation Method 1

The flexible elements extend from the surface in a span-wise direction of the blade and are operable to become rigid due to centrifugal stiffening at compressor operating speeds.

Methodology Applied

Scientific EffectCentrifugal stiffening: Centrifugal Force

Data Source

PatentEP2458224B1Compressor blade with flexible tip elements and process therefor

Publication Date: 2021.08.18 GENERAL ELECTRIC CO

Figure 1~4

AI summary

A compressor blade (22) and process for inhibiting rub encounters between a blade tip (26) of the blade (22) and an interior surface (42) of a case (24) that surrounds the rotating hardware within a compressor section (20) of a turbomachine. The compressor blade (22) includes a cap (28) that defines the blade tip (26) at a radially outermost end of the blade (22), and a plurality of flexible elements (30) extending from a surface (26) of the cap (28) that defines the blade tip (26). The flexible elements (30) extend from the surface (26) in a span-wise direction of the blade (22), and are operable to become rigid due to centrifugal stiffening at compressor operating speeds and, optionally, cut a groove (44) in the interior surface (42) of the case (24).