Serpentine Airfoil Cooling Passage with Platform Exit
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Solution Overview
Problem
Gas turbine engine airfoils experience undesired pressure losses and potential hot spots due to inadequate cooling, particularly in serpentine configurations where cooling air may not reach the tip, leading to the risk of burning through.
Innovation Solution
A serpentine cooling passage configuration with multiple radially extending passages, including up-pass and down-pass passageways forming a U-shape, and a platform cooling passageway connected to the exterior surface via cooling holes, ensuring effective cooling fluid distribution and exit at a location with low dump pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a serpentine cooling passage is used to cool the mid-body section of the airfoil, then cooling coverage is improved, but pressure losses increase and the configuration becomes more complex
Solution Approach 1:
The cooling passage is divided into multiple discrete passages (first passageway, second passageway, third passageway) that are spaced apart from one another. Each passage independently cools a specific region of the airfoil, distributing the cooling function across multiple channels rather than using a single continuous serpentine passage, thereby reducing pressure losses while maintaining comprehensive cooling coverage.
2Temperature
If the last passageway flows radially outward from the root, then cooling air reaches the tip effectively, but the device complexity increases
Solution Approach 1:
The passageways are designed to utilize the dynamic circumferential forces generated during turbine blade rotation. The first, second, and third passageways are positioned and oriented to leverage the pumping action created by centrifugal forces on the rotating blade, which automatically ensures cooling air reaches the tip without requiring complex active pumping mechanisms.
3Temperature
If multiple cooling passages are spaced apart in a chord-wise direction, then cooling distribution is improved, but the airfoil structure becomes more complex
Solution Approach 1:
Multiple cooling passages are distributed spaced apart from one another in the chord-wise direction of the airfoil. This segmentation allows each passage to serve a specific cooling zone, improving overall cooling distribution while the spacing arrangement maintains structural simplicity by avoiding the need for closely spaced or interconnected complex passages.
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 proposed cooling configuration ensures that cooling air reaches the tip of the airfoil, preventing hot spots and enhancing the efficiency of the gas turbine engine by effectively utilizing circumferential forces for fluid distribution.
Implementation Method 1
Having the last passageway flow radially outward takes advantage of pumping action from the circumferential forces on the turbine blade, which ensures cooling air reaches the tip of the last passage
Implementation Method 2
the cooling flow is fed into a serpentine passage from the root of the blade... ensures cooling air reaches the tip of the last passage... preventing hot spots
Data Source
AI summary
A gas turbine engine airfoil includes a platform, and spaced apart walls that provide an exterior airfoil surface that extends radially from the platform to an end opposite the platform. A serpentine cooling passage is arranged between the walls and has a first passageway that extends from the platform toward the end and a second passageway fluidly connecting to the first passageway and extending from the end toward the platform to an end. A platform cooling passageway is fluidly connected to the end and extends transversely into the platform. A cooling hole fluidly connects the platform cooling passageway to an exterior surface.