Radially Diffused Tip Flag Airfoil Cooling

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Solution Overview

Problem

The tip region of gas turbine engine airfoils experiences performance issues due to clearance, abrasion, and temperature effects, which are not effectively addressed by existing designs.

Innovation Solution

The airfoil design incorporates a tip squealer pocket and radially oriented hybrid skin core cavities to reduce thermal mass and thermal strain, with a rib defining a radial diffusion angle in the tip flag cavity, enhancing cooling efficiency and durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the airfoil tip region is designed with conventional structure, then the structural strength is maintained, but thermal mass and thermal strain are reduced

Engineering Contradiction:
Improvethermal massVSAvoidstructural strength
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The airfoil tip structure is segmented into multiple functional zones including a tip flag cavity, cooling channels, and a rib structure. This segmentation allows different regions to serve specific purposes: the tip flag cavity reduces thermal mass, the cooling channels dissipate heat, and the rib provides structural support. By dividing the tip region into distinct functional segments, the design achieves reduced thermal mass while maintaining structural integrity through distributed support elements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cooling channels are nested within the airfoil structure, with the tip flag cavity positioned radially outward and the cooling passages integrated into the airfoil body. This nested arrangement allows the cooling system to be embedded within the structural framework, enabling thermal management without compromising the overall structural strength. The rib structure is also nested within the tip region, providing internal support while maintaining the external aerodynamic shape.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Temperature

If cooling channels are added to the airfoil, then cooling efficiency is improved, but device complexity increases

Engineering Contradiction:
Improvecooling efficiencyVSAvoiddevice complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The rib structure in the tip flag cavity serves multiple functions simultaneously: it provides structural support to maintain airfoil shape, defines the radial diffusion angle for flow management, and acts as a boundary for the cooling channel. This multi-functionality reduces the need for separate components, thereby managing device complexity while achieving effective cooling. The cooling channels themselves are designed to serve both thermal management and structural reinforcement purposes.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The cooling channels are merged with the airfoil structural framework rather than being added as separate external components. The tip flag cavity and cooling passages are integrated into the existing airfoil geometry, combining thermal management functions with the structural framework. This merging approach reduces device complexity by eliminating the need for separate cooling system components and simplifying the overall structure.

Inventive Principle:
Principle #5Merging (Combining)

3Temperature

If the tip flag cavity is positioned closer to the leading edge, then cooling effectiveness is improved, but clearance issues arise

Engineering Contradiction:
Improvecooling effectivenessVSAvoidclearance
Core Design Contradiction:
TemperatureVSObject-affected harmful factors

Solution Approach 1:

The tip flag cavity is positioned at a specific radial location and axial position along the airfoil span, creating a localized cooling zone where it is most effective. The cavity is not uniformly distributed but strategically placed in regions of highest thermal demand while maintaining adequate clearance from the leading edge. This localized positioning optimizes cooling effectiveness in critical areas without compromising clearance requirements in other regions.

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 design reduces thermal transient and steady-state strains, improves cooling efficiency, and extends the durability of the airfoil components by optimizing thermal management and reducing material thickness.

Implementation Method 1

The airfoil design incorporates a tip squealer pocket and radially oriented hybrid skin core cavities to reduce thermal mass and thermal strain

Methodology Applied
Scientific EffectThermal mass reduction:

Implementation Method 2

The airfoil design incorporates a tip squealer pocket and radially oriented hybrid skin core cavities to reduce thermal mass and thermal strain

Methodology Applied
Scientific EffectThermal strain reduction:

Implementation Method 3

the rib defines a radial diffusion angle of the tip flag cavity

Methodology Applied
Scientific EffectRadial diffusion: Diffusion

Data Source

PatentEP3346094B1Radially diffused tip flag
Publication Date: 2021.08.04 RTX CORP
  • EP3346094B1 patent drawingFigure 1
  • EP3346094B1 patent drawingFigure 2
  • EP3346094B1 patent drawingFigure 3~4

AI summary

An airfoil (60) includes an airfoil body (90) having a first wall (120), a second wall (122), a third wall (124), a tip surface (126), and a rib (112). The first wall radially extends between a root region (96) and a tip region (98) and axially extends between a leading edge (100) and a trailing edge (102). The second wall radially extends from the tip region towards the root region and axially extends between the leading edge and the trailing edge. The third wall radially extends between the root region and the tip region and axially extends between the leading edge and the trailing edge. The tip surface circumferentially extends between the second wall and the third wall. The rib is radially spaced apart from the tip surface and circumferentially extends between the first wall and the third wall.