Turbine Blade Tip Trailing Edge Trench Cooling
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Solution Overview
Problem
Conventional turbine blade tip designs fail to adequately reduce leakage and efficiently cool the blade tip, particularly the trailing edge, which is difficult to cool due to its proximity to the turbine shroud and hot combustion gases, leading to inefficiencies and increased maintenance costs.
Innovation Solution
A turbine blade tip design featuring a trailing edge trench cavity that extends from the squealer tip cavity to the trailing edge, with a tip plate between the pressure and suction sidewalls, and trench cooling apertures to direct coolant flow effectively towards the trailing edge, enhancing cooling and reducing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the blade tip is positioned closely to the turbine shroud to minimize leakage, then leakage is reduced, but the blade tip is subjected to increased thermal load from hot combustion gases, making cooling difficult
Solution Approach 1:
The blade tip is segmented into multiple functional regions: a squealer tip cavity for cooling air storage, trailing edge trenches for coolant delivery, and a tip plate for structural support. This segmentation allows each region to address specific thermal and leakage challenges independently, enabling effective cooling while maintaining close proximity to the shroud.
Solution Approach 2:
Coolant air acts as an intermediary substance that is channeled through the blade tip structure via trenches and cavities. This intermediary cooling fluid enables the blade tip to be positioned close to the hot shroud while maintaining acceptable temperatures through active cooling mediation.
2Ease of manufacture
If conventional blade tip designs are used, then manufacturing is simpler, but cooling effectiveness at the trailing edge is insufficient
Solution Approach 1:
The blade tip incorporates local quality variations through the trailing edge trenches and squealer cavity that are absent from conventional uniform designs. These localized features concentrate cooling resources precisely where thermal load is highest, improving cooling effectiveness without requiring complete redesign of the entire blade tip structure.
3Temperature
If more cooling air is discharged through the blade tip, then cooling effectiveness improves, but compressor bypass air usage increases, reducing engine efficiency
Solution Approach 1:
The blade tip cooling system is designed to be self-regulating, using the natural flow of cooling air through the integrated trenches and cavities to achieve effective cooling. The geometry of the cooling passages directs coolant flow automatically to critical areas without requiring excessive external cooling air, thereby reducing compressor bypass air usage and improving overall engine efficiency.
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 design improves cooling efficiency at the trailing edge, reduces oxidation, and enhances aerodynamic performance by directing coolant flow effectively, thereby increasing part life and engine efficiency while minimizing the use of compressor bypass air.
Implementation Method 1
a trailing edge trench originating at an aft end of the squealer tip cavity, wherein the trailing edge trench generally extends toward the trailing edge of the blade tip
Implementation Method 2
a tip plate that extends between the outer radial edge of the pressure sidewall to the outer radial edge of the suction sidewall
Data Source
Figure 1
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AI summary
A blade tip (38) of a turbine rotor blade (18) for a gas turbine engine, the turbine rotor blade (18) including an airfoil (24) and a root portion (36) for mounting the airfoil (24) along a radial axis to a rotor disk (16) inboard of a turbine shroud (20), a pressure sidewall (28) and a suction sidewall (30) that join together at a leading edge (32) and a trailing edge (34), the pressure sidewall (28) and suction sidewall (30) extending from the root portion (36) to the blade tip (38), and a squealer tip cavity (62) formed at the blade tip (38), the blade tip (38) including a trailing edge trench (72) originating at an aft end of the squealer tip cavity (62), wherein the trailing edge trench (72) generally extends toward the trailing edge (34) of the blade tip (38).