Combined Tip Flag Blade Core for Serpentine Airfoil Cooling
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Solution Overview
Problem
Existing gas turbine engine airfoil designs face challenges in achieving high internal heat transfer and maintaining cool tip temperatures, particularly in the serpentine cooling channels, which often end in dead-ends and experience flow separation and low heat transfer, leading to thermal mechanical fatigue and poor cooling efficiency.
Innovation Solution
The introduction of a serpentine channel with a tip flag channel and a metering orifice that connects radially and axially extending passages, controlling the pressure drop to enhance cooling fluid flow and increase heat transfer, thereby reducing tip temperatures and improving thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a dead-ended serpentine cooling channel is used, then the cooling circuit is simple to manufacture, but the internal heat transfer is low and flow separation occurs
Solution Approach 1:
The cooling channel is segmented into multiple sections: an incoming passage, a serpentine passage, and an outgoing passage. This segmentation allows the cooling fluid to flow continuously through distinct functional zones, improving heat transfer efficiency in the serpentine section while maintaining manufacturing simplicity through modular construction.
Solution Approach 2:
The cooling channel transitions from a two-dimensional serpentine pattern to a three-dimensional structure by adding vertical components. The incoming and outgoing passages extend in the vertical direction, creating a multi-level flow path that enhances heat transfer surface area and prevents flow separation while maintaining a compact footprint suitable for manufacturing.
2Device complexity
If the serpentine channel ends in a dead-end, then the cooling circuit design is simplified, but flow separation and low heat transfer occur
Solution Approach 1:
Instead of ending the serpentine channel in a dead-end, the design inverts the approach by providing a continuous flow path through an outgoing passage. The cooling fluid flows from the serpentine section into the outgoing passage, which directs it toward the tip region, ensuring continuous heat transfer and preventing flow separation at the channel end.
Solution Approach 2:
The cooling circuit maintains continuous fluid flow through the entire channel system, from the incoming passage through the serpentine section and into the outgoing passage. This continuity ensures that heat transfer action is sustained throughout the channel length without interruption or flow separation, improving overall thermal management effectiveness.
3Area of stationary object
If cooling air is passed through long serpentine channels, then the cooling circuit provides extensive cooling coverage, but heat pick-up increases and cooling effectiveness decreases
Solution Approach 1:
The incoming passage is positioned to deliver cooling fluid to the serpentine channel at an optimal location and temperature. By preparing the cooling fluid flow in advance through the incoming passage, the system ensures that the fluid enters the serpentine section with maximum cooling potential, reducing heat pick-up before it occurs in the extended cooling channels.
Solution Approach 2:
The incoming and outgoing passages act as intermediary elements between the cooling fluid source and the serpentine cooling channels. These intermediary passages optimize the flow distribution and pressure characteristics, enabling the serpentine channels to maintain effective cooling over extended lengths while minimizing heat pick-up through improved flow management.
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 solution enhances internal heat transfer and maintains cool tip temperatures by directing cooling fluid effectively through the tip flag channel, reducing thermal mechanical fatigue and improving the lifespan of the airfoil.
Implementation Method 1
The metering orifice can have a cross-sectional area selected to reduce a pressure of a fluid flow exiting the first tip flag passage to a value equal to or less than a pressure of a fluid exiting the final passage of the serpentine channel
Implementation Method 2
The cooling circuit includes a serpentine channel having a plurality of radially extending passages connected in flow series from a first passage to a final passage
Data Source
Figure 1
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AI summary
A cooling circuit of an airfoil (78) for a gas turbine engine includes a serpentine channel (216) having a plurality of fluidly connected radially extending flow passages (224, 226, 228) and a tip flag channel disposed adjacent to the serpentine channel (216). The tip flag channel includes a first tip flag passage (218a) extending radially outward and a second tip flag passage (218b) extending axially aftward from a terminal end of the first tip flag passage (218a), the second tip flag passage (218b) disposed radially outward of the serpentine channel (216). The second tip flag passage (218b) is in direct fluid communication with each of the first tip flag passage (218a) and a final passage (228) of the serpentine channel (216).