Splayed Tip Features for Gas Turbine Airfoil Cooling
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Solution Overview
Problem
Gas turbine engine turbine blades experience trailing edge tip corner burning/creep due to high temperature stress, despite advances in cooling technologies like refractory metal core casting, which allows for smaller and more complex passages but still faces challenges in effectively managing thermal energy removal.
Innovation Solution
The design incorporates a trailing edge tip corner with multiple corner features, such as oblong or teardrop-shaped channels, splayed between the suction and pressure sides of the turbine blade, which form constant, divergent, or convergent channels, and are recessed within trenches to enhance cooling airflow and heat pickup, utilizing a combination of Refractory Metal Core (RMC) and ceramic core for casting complex geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cooling passages are used in turbine blades, then the blade structure is simpler to manufacture, but trailing edge tip corner burning/creep occurs due to insufficient cooling coverage
Solution Approach 1:
The cooling system is segmented into multiple corner features (pedestals, ribs, or struts) distributed along the trailing edge tip corner region. Each corner feature acts as an independent cooling element with its own channels, creating a segmented cooling architecture that provides comprehensive coverage of the high-stress trailing edge tip corner area while maintaining manufacturability through modular construction
Solution Approach 2:
Corner features are specifically positioned and configured to provide localized cooling enhancement at the trailing edge tip corner region where burning/creep occurs. The features include channels that direct cooling air precisely to the high-temperature zones, with varying geometries (oblong, teardrop shapes) optimized for local heat transfer requirements rather than uniform cooling throughout the blade
2Reliability
If refractory metal core casting is used to create complex passages, then cooling air flow coverage is improved, but manufacturing complexity increases
Solution Approach 1:
The casting process uses a composite core structure combining refractory metal core material with ceramic core material. The refractory metal core provides the complex corner feature geometries (pedestals, ribs, struts) with high thermal resistance, while the ceramic core material facilitates the casting process and can be removed after casting. This composite approach enables complex cooling passage geometries while maintaining manufacturing feasibility
Solution Approach 2:
The ceramic core material serves as an intermediary in the casting process, allowing the creation of complex refractory metal core geometries that would be difficult to manufacture directly. The ceramic core is formed first, then the refractory metal core is built around it, and finally the ceramic is removed after casting, leaving the desired complex cooling passage structure
3Reliability
If cooling air flow is increased to reduce thermal stress, then trailing edge tip corner burning is mitigated, but energy loss increases
Solution Approach 1:
The corner features concentrate cooling air flow specifically at the trailing edge tip corner region where thermal stress and burning/creep occur, rather than distributing cooling air uniformly throughout the entire blade. This localized cooling approach provides enhanced protection at the critical high-temperature zone while minimizing the total amount of cooling air required, thereby reducing energy loss
Solution Approach 2:
The cooling system is divided into multiple discrete corner features (pedestals, ribs, or struts) that segment the cooling air flow into multiple targeted streams. This segmentation allows the cooling air to be distributed to multiple high-temperature zones along the trailing edge tip corner, improving coverage and thermal stress resistance while using less total cooling air compared to a single large cooling passage
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 configuration improves cooling airflow coverage and heat management, reducing thermal stress and minimizing mixing losses, thereby mitigating trailing edge tip corner burning/creep and enhancing the durability of gas turbine engine components.
Implementation Method 1
In forced convection cooling, compressor bleed air flows through internal cavities of hot section blades and vanes to continuously remove thermal energy
Implementation Method 2
compressor bleed air flows through internal cavities of hot section blades and vanes to continuously remove thermal energy
Implementation Method 3
The internal cavities often communicate with a trailing edge cavity that directs cooling air around an internal pedestal array to axially exit through a trailing edge passage of the blade
Data Source
AI summary
A component for a gas turbine engine includes a trailing edge tip corner that at least partially defines a trailing edge cavity and a multiple of corner features within the trailing edge cavity, the multiple of corner features splayed along the trailing edge tip corner.