Gas Turbine Blade Tip Offset Cooling Channels

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Solution Overview

Problem

The 'tip section offset' technique in turbine blades disrupts the effectiveness of conventional cooling systems, particularly at the blade tip, which is the hottest location and subjected to high temperatures, leading to compatibility issues and reduced lifespan.

Innovation Solution

A hollow blade design with an internal cooling passage and a projecting portion on the pressure side wall that slopes and includes cooling channels opening into a terminal face, allowing for effective cooling while maintaining compatibility with the 'tip section offset' configuration, thereby enhancing cooling performance and film cooling of the pressure side rim.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the tip section offset technique is used to reduce kinetic energy losses, then the blade performance is improved, but the cooling system effectiveness at the blade tip is disrupted

Engineering Contradiction:

Improvekinetic energy lossesVSAvoidcooling system effectiveness

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The blade tip is segmented into multiple airfoil sections (first, second, and third sections) with different offset configurations. The first section has a larger offset towards the pressure side, while the second and third sections have progressively smaller offsets, allowing each segment to serve different functional requirements for both performance and cooling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different offset configurations are applied locally to different sections of the blade tip. The first section closer to the free end has a more pronounced offset to maximize performance benefits, while the second and third sections have reduced offsets to preserve cooling effectiveness, creating a gradient of local properties along the blade.

Inventive Principle:

Principle #3Local quality

2Duration of action of stationary object

If the blade tip is cooled effectively to extend lifespan, then the blade durability is improved, but the complexity of the cooling system increases

Engineering Contradiction:

Improveblade lifespanVSAvoidcooling system complexity

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The cooling channels are integrated directly into the blade structure, merging the cooling function with the aerodynamic surface. The cooling passages are formed within the blade body itself, eliminating the need for separate cooling components and reducing overall system complexity while maintaining effective cooling.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The blade structure serves multiple functions simultaneously: the airfoil sections generate aerodynamic force, the cooling channels provide thermal management, and the offset configuration reduces kinetic energy losses. This multi-functionality reduces the need for additional dedicated cooling components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If cooling channels are positioned to access the blade tip, then cooling effectiveness is improved, but the manufacturing accessibility is reduced

Engineering Contradiction:

Improvecooling effectivenessVSAvoiddrilling access

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The cooling channels are oriented at specific angles relative to the blade surface, utilizing the third dimension (depth/thickness of the blade) to route cooling air from accessible external locations through the blade structure to the tip region, making both manufacturing and cooling effective.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 design enables the conservation of high cooling system effectiveness at the blade tip, improving thermal pumping and film cooling, while allowing for drilling access without degrading mechanical robustness or increasing weight, thus extending the blade's lifespan under high temperature conditions.

Implementation Method 1

improving thermal pumping and film cooling

Methodology Applied

Scientific EffectThermal pumping:

Implementation Method 2

improving thermal pumping and film cooling

Methodology Applied

Scientific EffectFilm cooling:

Implementation Method 3

internal cooling passage inside the airfoil

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9605545B2Gas turbine blade with tip sections offset towards the pressure side and with cooling channels

Publication Date: 2017.03.28 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A hollow blade including an airfoil extending along a longitudinal direction, a root, a tip, an internal cooling passage, and an open cavity defined by an end wall and a rim, together with cooling channels connecting the internal cooling passage to a pressure side. The cooling channels slope relative to the pressure side. A stack of airfoil sections of the blade at a level of the rim of the tip of the blade are offset towards the pressure side. The pressure side wall of the airfoil includes a projecting portion and cooling channels arranged in the projecting portion to open out into a terminal face of the projecting portion.