Gas Turbine Nozzle End Wall Cooling via Discrete Holes
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Solution Overview
Problem
Current gas turbine airfoil cooling methods are inefficient in distributing cooling air effectively across the end wall, leading to reduced thermal efficiency and increased cooling air usage.
Innovation Solution
The design incorporates an inner and outer band end wall portion with a cooling passage and strategically arranged cooling holes in the circumferential direction, with denser intervals in areas of lower sealing air flow rate to prioritize cooling of high-temperature regions, reducing the overall amount of cooling air required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is discharged into the gas path flow at a position on the airfoil-leading edge side of the inner band end wall, then cooling performance is improved, but the amount of cooling air required increases
Solution Approach 1:
The patent applies local quality by providing cooling air discharge ports specifically at the airfoil-leading edge side of the inner band end wall, where cooling is most needed. This localized cooling approach targets the high-temperature region directly, improving cooling performance while minimizing the total amount of cooling air required compared to uniform cooling of the entire end wall.
Solution Approach 2:
The patent uses the cavity defined in cooperation with the upstream bucket as an intermediary space to receive and distribute cooling air. The cooling air is discharged into this cavity rather than directly into the gas path, allowing for more efficient heat transfer and reducing the overall cooling air requirement while maintaining effective cooling at the leading edge region.
2Temperature
If cooling air is continuously jetted from slit-like jetting ports toward the seal fin, then cooling of the sealing device is improved, but device complexity increases
Solution Approach 1:
The patent segments the cooling function by separating the cooling of the airfoil body from the cooling of the end wall and sealing device. The air passage in the inner band end wall is connected to the inner cooling passage of the nozzle, creating a dedicated cooling path for the sealing device. This segmentation allows for simplified, targeted cooling without requiring a complex integrated cooling system.
Solution Approach 2:
The air passage and jetting ports in the inner band end wall serve multiple functions: they cool the end wall structure itself and simultaneously cool the seal fin through continuous jetting. This multi-functionality reduces the need for separate cooling systems, thereby reducing overall device complexity while maintaining effective cooling of the sealing device.
Data Source
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AI summary
A gas turbine nozzle is provided for achieving an improved cooling performance of an end wall and an improved thermal efficiency of a gas turbine. The gas turbine nozzle (300) includes an airfoil portion (310) having a cooling passage (320) therein, and an end wall portion (100) located at an inner band end portion of the airfoil portion (310) in the turbine radial direction. Cooling holes (130) are disposed in the leading edge side hook portion (110) of the end wall portion. The plurality of cooling holes (130) are arranged with different distances therebetween in the circumferential direction of the gas turbine. Cooling air (700) flowing in the cooling passage (320) is configured to flow from the cooling holes (130) toward the leading edge (101) of the end wall portion (100).