Trailing Edge Cooling Holes Orthogonal to Apogee

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for cooling gas turbine engine aerofoils, particularly at the trailing edge, face challenges in maintaining aerodynamic efficiency due to thickness variations and scarring from drilling holes for coolant delivery, which affects the mechanical strength and efficiency of the blades at elevated temperatures.

Innovation Solution

The proposed solution involves drilling cooling holes orthogonally to the apogee surface of the trailing edge, allowing for a thinner apogee thickness and improved aerodynamic surface finish, with holes extending from the apogee onto adjacent surfaces, enhancing coolant delivery and aerodynamic performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If holes are drilled into the cast aerofoil near the apogee using conventional methods, then cooling effectiveness is improved, but surface scarring and positional variation occur which deteriorate aerodynamic efficiency

Engineering Contradiction:

Improvecooling effectivenessVSAvoidsurface finish quality

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

Instead of drilling holes from the pressure surface side as in conventional PSE systems, the patent inverts the approach by drilling holes from the suction surface side through the apogee region. This inversion allows the drill bit to enter perpendicular to the apogee surface, eliminating scarring and positional variation while maintaining cooling effectiveness through the trailing edge.

Inventive Principle:

Principle #13The other way round (Inversion)

2Shape

If the apogee thickness is reduced to improve aerodynamic efficiency, then aerodynamic performance is improved, but the ability to drill cooling holes effectively is reduced

Engineering Contradiction:

Improveaerodynamic efficiencyVSAvoiddrilling capability

Core Design Contradiction:

ShapeVSEase of manufacture

Solution Approach 1:

The patent inverts the conventional drilling approach by drilling from the suction surface side through the apogee rather than from the pressure surface side. This allows effective cooling hole drilling even with reduced apogee thickness (0.2-0.5mm) because the drill enters perpendicular to the surface at the thinnest point, ensuring proper hole formation without requiring excessive thickness.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the drilling parameters by altering the entry angle from the conventional shallow angle to a perpendicular entry through the apogee. This parameter change enables effective cooling hole formation in thinner apogee sections while maintaining manufacturing feasibility.

Inventive Principle:

Principle #35Parameter changes

3Strength

If adaptive machining is performed prior to drilling to reduce apogee thickness, then handling damage is reduced, but EDM capability is not improved due to uneven surface and shallow entry angle requirements

Engineering Contradiction:

Improvehandling durabilityVSAvoiddrilling process quality

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent inverts the drilling sequence and approach by drilling from the suction surface side through the apogee after adaptive machining, rather than from the pressure surface side before machining. The perpendicular entry through the apogee eliminates the shallow entry angle problem, allowing high-quality hole formation even with the uneven surface created by adaptive machining, while the reduced apogee thickness (0.2-0.5mm) prevents handling damage.

Inventive Principle:

Principle #13The other way round (Inversion)

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 approach enables longer, more effective cooling holes with reduced scarring and positional variation, improving cooling effectiveness and aerodynamic benefits by positioning holes along the apogee, thus addressing the limitations of prior art methods.

Implementation Method 1

a row of holes is provided to a pressure surface side or a suction surface side... the holes in fluid communication with one or more of the cavities... outlets to the holes extend from the apogee and onto an adjacent part of the pressure surface side or suction surface side

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

coolant from a coolant source... cooling effectiveness... improving cooling flow efficiency

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10641104B2Trailing edge ejection cooling

Publication Date: 2020.05.05 ROLLS ROYCE PLC

AI summary

A hollow aerofoil is described having a leading edge and a trailing edge. The leading edge and trailing edge are connected by a pressure surface side (34) and a suction surface side (37) and one or more cavities are bounded by the pressure surface side (34) and/or suction surface side (37). In use, the cavity is arranged to receive coolant from a coolant source. The trailing edge has an apogee (36) where the pressure surface side (34) and suction surface side (37) meet. In an embodiment, a row of holes (32) is provided to a pressure surface side of a centreline of the apogee (36), the holes (32) being in fluid communication with cavity. The arrangement of the holes is such that outlets (33) to the holes extend from the apogee (36) and onto an adjacent part of the pressure surface side (34). A method for the manufacture of the aerofoil is also described.