Airfoil Trailing Edge Variable Land Width Cooling
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Solution Overview
Problem
Gas turbine engine blades experience thermal stresses and fatigue due to exposure to high temperatures, leading to reduced lifespan as existing cooling methods are inadequate in managing temperature differences across the blade.
Innovation Solution
An internally cooled airfoil design with a hollow interior and distributed trailing edge slots, where lands of varying widths along the span direction create a serpentine coolant path to enhance cooling, particularly at the mid-span section, while maintaining a constant pitch between lands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform cooling is applied across the blade, then manufacturing is simpler, but thermal stresses and fatigue increase due to inadequate cooling at critical sections
Solution Approach 1:
The patent applies local quality by varying the land width at different span positions of the airfoil. The trailing edge slots have different land widths at the mid-span section compared to other sections, creating enhanced cooling specifically where thermal stresses are highest. This localized variation in cooling intensity addresses the reliability issue without requiring complete redesign of the entire cooling system, thus balancing manufacturing complexity with improved blade lifespan.
2Reliability
If variable land width is implemented to enhance cooling at mid-span, then thermal stress reduction improves, but device complexity increases
Solution Approach 1:
The cooling structure is segmented into multiple trailing edge slots distributed along the span direction, with each slot having specific land width characteristics. This segmentation allows independent optimization of cooling at different locations without requiring a completely complex integrated system. The constant pitch between lands provides a regular pattern that simplifies manufacturing while the variable land widths within segments address thermal stress management.
Solution Approach 2:
The patent changes the geometric parameter of land width along the span direction to optimize cooling distribution. By varying this single critical parameter while maintaining constant pitch, the design achieves improved thermal stress management without proportionally increasing overall device complexity. This parameter-based optimization is more manageable than redesigning the entire cooling architecture.
3Manufacturing precision
If constant pitch between lands is maintained, then manufacturing precision is easier to control, but cooling distribution flexibility is reduced
Solution Approach 1:
The design maintains constant pitch between lands throughout the span to ensure manufacturing precision and regularity. However, it compensates for this constraint by varying the land width at different locations, particularly at the mid-span section. This allows the cooling distribution to be adapted to local thermal stress requirements while keeping the spacing pattern simple and manufacturable.
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 effectively reduces thermal stresses and enhances cooling, thereby extending the lifespan of the rotor blades by optimizing coolant distribution and managing temperature variations across the blade.
Implementation Method 1
a plurality of trailing edge slots distributed along the spanwise direction, the trailing edge slot being in flow communication with the hollow interior of the airfoil
Implementation Method 2
The design effectively reduces thermal stresses and enhances cooling, thereby extending the lifespan of the rotor blades
Data Source
AI summary
An internally cooled airfoil, such as a turbine blade, has an airfoil section extending between a tip and a root. The interior of the airfoil includes a distribution of lands at the trailing edge in the span direction. A width of each of the lands is a widest dimension in the span direction of the land in the interior of the airfoil. A pitch is a distance in the span direction between centerlines of two adjacent lands. The pitch is constant throughout the distribution of the lands. The distribution of the lands includes at least two different widths.